On Tue, 14 Jun 2016 11:19:15 -0400 Alvin Starr via talk <talk@gtalug.org> wrote:

With magical crashes I usually try to see if I can get any diagnostics out a serial console because once in graphical mode a crashing system usually has just a black screen. Booting and running memtest would be a good idea. I am assuming that the system does not have ECC memory so bad memory could cause all kinds of funky problems. Even if it has ECC depending on the motherboard failures can cause reboots.

the 6300 is non ecc ddr3, I had a similar problem once and it turned out to be a contact issue i ran the system with the mb isolated from the case on an anti static pad - If it is a contact / power issue there will be no logs, reports or diagnostic info It could also be some other things, but my money is on contact/power/mb as you have a reset at random times and under random load hth Andre

On 06/14/2016 11:10 AM, D. Hugh Redelmeier via talk wrote:

...

We have a computer that started doing random and frequent restarts on the weekend. We don't know why.

Any suggestions?

It looks as if the power dips momentarily and the computer reboots, with no message that we have observe. But it could just as easily be a crash of some other kind that leaves no trace.

The system is an HP Compaq Pro 6300 Small Form Factor PC running Fedora 20.

The crash seems to be at different points (i.e. not one consistent software activity). The crashes don't seem correlated with heavy workloads (eg. it crashed a couple of times while I was staring at log files to see if there was any hint of the problem).

Hypothesis: a Fedora 20 bug. But the software has not been changed in months. Updates have not been appled this year. Since the behaviour has changed without the software changing, I don't think that Fedora is to blame.

Hypothesis: it might be heat-related (the room it is in gets warm). I vacuumed out the interior and defuzzed the heat sinks. This did not improve the uptime.

Hypothesis: it might be contact-related. So I disconnected and reconnected most internal connectors and reseated the memory. This did not seem to improve the uptime.

Hypothesis: it might be the power supply. Normally, I'd swap power supplies to test this hypothesis but this Small Form Factor computer has a unique (and probably expensive) power supply. I opted to move the disk to a Dell OptiPlex 990 Small Form Factor computer and use that.

The Dell, with the HP's disk, seems stable. No rebooting. This is in the same warm room, but the weather has changed.

In the original HP box, I installed a disk that I had laying around (a 60G drive from a discarded laptop), installed Ubuntu 16.04, and have been running four CPU-bound processes for 24 hours. No crash. I admit that this is in a cooler room. The heat and power load of a laptop drive is less than that of a 3.5" HDD, but I would not think that that is significant.

The computer is a couple of years old but still has a year of warranty. There are confidential files on the disk drive so I'd like to narrow down the problem before calling in HP support. Asking for a particular replacement part is more convenient that shipping the computer back to HP. --- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

On 06/14/2016 11:23 AM, Russell Reiter via talk wrote:

On 6/14/16, D. Hugh Redelmeier via talk <talk@gtalug.org> wrote:

...

We have a computer that started doing random and frequent restarts on the weekend. We don't know why.

Any suggestions? You don't mention whether or not the system is protected by UPS.

I live in an area with somewhat spotty electrical service, an older building near the exhibition grounds. When they liven up the CNE grounds in the spring, I experience brown-outs quite often.

Most recently the city has replaced the streetcar overhead wires and de-energized and re-energized the system, both times I had spontaneous reboots. One of the TTC engineers told me the new streetcars require more voltage and they are replacing the wires with heavier gauge ones throughout the city.

Are you near streetcar tracks where they may be replacing wiring or perhaps near one of the transformers which convert AC to DC?

As a note I have been burned by lower cost UPSs and heavily loaded servers with no hold time in the power supplies. A lot of UPSs switch from the mains to battery once the power drops and that delay can be enough to cause some power supplies to lose enough power to fail. -- Alvin Starr || voice: (905)513-7688 Netvel Inc. || Cell: (416)806-0133 alvin@netvel.net ||

On 06/14/2016 10:24 PM, Bob Jonkman via talk wrote:

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Alvin Starr wrote:

...

A lot of UPSs switch from the mains to battery once the power drops and that delay can be enough to cause some power supplies to lose enough power to fail If that happens then your UPS is broken. The whole point of a UPS is to supply *uninterruptable* power. Even the simplest pass-through UPSes I know about can switch from line to battery in the space of a single waveform (ie. within 1/60th of a second). Not much point in having a UPS if it makes all your equipment reboot when the power goes out.

The answer "your UPS is broken" is a bit simplistic. What I had is what you get from buying an inexpensive APC UPS and very heavily loaded server with a badly designed power supply. I stole this from http://www.mpoweruk.com/ups.htm. Off Line or Standby UPS These are simple inexpensive systems providing only basic protection. In normal situations the UPS passes the mains power directly to the load. The mains power provides a single DC line which keeps the battery charged. When the UPS detects a voltage too low, it turns on the inverter to power the load from the battery. The system is relatively slow (longer than 4 ms) and the delay between mains power loss and inverter startup can be long enough to disrupt the operation of some sensitive loads. This technology does not normally provide full time power conditioning but it may use a simple filter to clip spikes and electrical noise. On Line or No Break UPS These are designed to provide a zero transfer time, with better voltage and frequency regulation than that can be achieved by off line and line interactive UPS. In on line systems the mains power is used to provide two DC power lines which feed both the charger and the inverter which is permanently turned on providing the AC power to the application. When the mains fails, the inverter instantaneously draws its DC supply from the battery instead of the mains. The method by which the AC load is permanently supplied by the system inverter and not the mains is called "double conversion" since the charger provides the AC-DC conversion and the inverter converts the DC back to AC again. On line systems typically provide full power conditioning, protecting the load from all forms of power disturbances, including brownouts, blackout, transient surges or sags. In the event of a mains power failure, there is no delay or transfer time to backup power. These systems are however more costly and have both higher power consumption, and higher heat generation. Line Interactive UPS These systems contain an off-line inverter but also use a transformer to supply to the load. In the event of a mains failure the inverter is started and switched to the transformer to provide the output. The transformer is used to provide line conditioning however it also maintains output on its secondary briefly when a total outage occurs increasing the hold up time of the UPS. This results in a break in the output of a few milliseconds or less and is thus faster than a simple off line UPS. Also take a look at: http://www.repeater-builder.com/backup-power/ups-test.html It provides a good look at what is actually going on when your UPS from CanadaComputers,NCIX,BestBuy... switches. You will notice that the provided voltage lags a bit and depending on the timing you could lose up to a whole cycle. This was also a test with a clean line drop. In the case where the peak voltage drops before the power fails completely then you have a more complex set of problems. I remember reading the specs of one UPS that would kick in if the input voltage dropped below 90V. 90V may be too low for some equipment and will cause power supplies to have even lower hold times. This is why you need to test your UPS and equipment configuration from time to time and buy online UPS's when ever possible. -- Alvin Starr || voice: (905)513-7688 Netvel Inc. || Cell: (416)806-0133 alvin@netvel.net ||

<snip>

...

grounds in the spring, I experience brown-outs quite often.

That sounds fun.

Spring and fall like clockwork plus one or two for good measure the rest of the year. I certainly wouldn't be able to run any enterprise without significant UPS under those conditions. Fortunately it's just me and the few fsck operations it causes aren't an issue for me. In seven years I haven't had a catastrophic drive failure, just some uuid corruptions; trivial to deal with.

...

Most recently the city has replaced the streetcar overhead wires and de-energized and re-energized the system, both times I had spontaneous reboots. One of the TTC engineers told me the new streetcars require more voltage and they are replacing the wires with heavier gauge ones throughout the city.

You only get to run one voltage on the system. They might require more current though, and thicker wires would help with that.

Well he did say voltage but perhaps he was referring to when the old fleet is entirely retired. For now they might be modifying the older still serviceable cars to deal with higher voltage in some way.

-- Len Sorensen

<snip> at the same time), then they would be able

to keep the old wires since higher voltage reduces the need for higher

All the current infrastructure is EOL this is why it is being changed.

current to provide the same power. Of course swapping all that out at once is not an option, so the voltage is not changing. So instead if you want more power capacity, you need more current which means thicker wires. Conviniently that can be done area by area.

The wires are of course also being updated to work with the pantograph system, which means fixing all the intersections and curves, and eventually making the straight sections move side to side a bit rather than being completely straight (which apparently wears a nice groove into pantographs). After all the plan apparently is that only the first 60 or so of the new streetcars will have trolley poles, while the rest will only have a pantograph (the first 60 have both).

From Wikipedia bit on transport pantograph

"Pantographs with overhead wires are now the dominant form of current collection for modern electric trains because, although more fragile than a third-rail system, they allow the use of higher voltages."

-- Len Sorensen

<snip>

Streetcars use 600V as does the subway. The new Eglinton line will be 750V though and won't have loops for turning around.

You don't think that the TTC might be forward planning for 750V all around? Remember it was TTC staff I spoke to who told me the change was to accommodate higher voltage.

-- Len Sorensen

<snip>

Just *imagine* the size of the series resistor you would have to install to drive one of those 600V motors with 750V ;-)

I don't know but it could probably be done. On the other hand, I did observe the the effects of running a new unit at 600V, when they tested the three segment unit in front of my apt on the tight turn. There were dull yellow sparks flying every time it hit a bearing point.

--- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

Sure they might be bigger sparks with the 50% higher power demand the new trains have.

During an ice storm, I watched from the Electrical Building on Church as one of the streetcar overhead lines dropped onto the rails. Man, that was exciting..and then I guess a breaker blew somewhere. -- Peter Hiscocks Syscomp Electronic Design Limited, Toronto http://www.syscompdesign.com USB Oscilloscope and Waveform Generator 647-839-0325

Modern motor controllers can be quite tolerant of significant voltage variation. However, I doubt they're changing the voltage.

I'm not a power systems engineer, but it could be that changing the supply voltage would be a matter of changing taps on a transformer. As for flag day - I remember as a kid when there was a changeover to 60Hz in the hydro system. (Was it 20Hz before that? Something much lower.) Anyway, every electric motor in the house had to be changed. Must have cost a fortune. P. -- Peter Hiscocks Syscomp Electronic Design Limited, Toronto http://www.syscompdesign.com USB Oscilloscope and Waveform Generator 647-839-0325

On 06/14/2016 10:02 PM, ted leslie via talk wrote:

I always thought it was 60hz for ever!, but (googling) 25 -> 60 in 1949+/-, (in canada) you're no spring chicken!! :)

A few years ago, I read a book about power systems in Ontario. There were a few different frequencies, other than 25 & 60 Hz. There were even rotary converters (combination motor & alternator in one unit) to change the frequency. I seem to recall there was still one to convert to 25 Hz for industrial users in the Buffalo area.

On 06/15/2016 10:12 AM, Lennart Sorensen wrote:

On Tue, Jun 14, 2016 at 10:15:43PM -0400, James Knott via talk wrote:

...

A few years ago, I read a book about power systems in Ontario. There were a few different frequencies, other than 25 & 60 Hz. There were even rotary converters (combination motor & alternator in one unit) to change the frequency. I seem to recall there was still one to convert to 25 Hz for industrial users in the Buffalo area. Apparently there was 25Hz produced at Niagara for industrial users until 2009. The cost to change all that equipment was considered too high and not worth it.

IIRC, it was produced at the plant upstream from the falls, which is now a museum. Also, 25 Hz power was still running the Fort Erie area, until 1966. https://en.wikipedia.org/wiki/Ontario_Hydro

As a director (again) of that project, I'm glad you like it, and I appreciate that you're not blaming your outages on it. I'd be more likely to attribute them to the Strachan substation, which is under colossal pressure from all the new condo builds. The city is trying to build a relief line and new substation capacity, but getting past objections is tough.

I always thought it a shame that the windmill was only used to generate hydrogen for the hybrid fleet. It would have been nice to have it feed the grid, although I'm not sure if that has changed since I last read the plaque at the base of it.

The wind turbine has a rather nice AC (variable frequency)-DC-AC (60 Hz) inverter. I imagine the new streetcars have something similar.

I believe that some pantographic transportation corridors hop between AC and DC using similar tech. It would have been nice if Smartrack could have been realized along those lines. However, I think everyone but the mayor's team recognized track gauge matching between any kind of urban LRT and the GO corridor would be problematic among all the other electrification issues.

On DC, New York retired its last DC infrastructure only a few years ago. The very last few DC customers now have rectifiers installed in their basements, but are still charged the absurdly high DC metering price for their power. I'm led to believe these are heritage buildings with historic elevators and lighting which can't be replaced and remain within code without tearing everything out.

cheers, Stewart --- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Stewart wrote:

The coolest and cleverest hydrogen energy thing in the province, though, sits and runs quietly in a nondescript box at Sheppard E & Vic Park. Most people don't know it's there.

You can't just write that, and then say "Cheers". That's cruel and unusual punishment for us geeks. - --Bob. On 2016-06-15 06:09 PM, Stewart C. Russell via talk wrote:

On 2016-06-15 04:29 PM, Russell Reiter wrote:

...

I always thought it a shame that the windmill was only used to generate hydrogen for the hybrid fleet. It would have been nice to have it feed the grid

It *always* has fed the grid. That hydrogen station coincidentally connected to the grid, and their claim that all the power for their process came from the turbine was utterly wrong. We tried to get them to change their plaque, but they wouldn't. I think the H₂ station has gone now.

The whole Hydrogen Economy thing kind of fizzled out a few years ago. The coolest and cleverest hydrogen energy thing in the province, though, sits and runs quietly in a nondescript box at Sheppard E & Vic Park. Most people don't know it's there.

cheers, Stewart --- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Alvin wrote:

The hydrogen to power process works quite well. The problem is getting hydrogen into a convenient storage format.

A few (10?) years ago I head a Science Friday show with guest George Olah where he made a strong case for using hydrogen, but storing and transporting it as methanol. It can be used directly (burned), have the hydrogen stripped off and used in hydrogen fuel cells, and there are methanol fuel cells. Methanol can be produced directly from carbon dioxide. But the best part was that since methanol is a liquid, all our current gasoline distribution and storage can be used without a fundamental change in infrastructure. Don't know why this hasn't taken off... - --Bob. https://en.wikipedia.org/wiki/Methanol_economy - -- Bob Jonkman <bjonkman@sobac.com> Phone: +1-519-635-9413 SOBAC Microcomputer Services http://sobac.com/sobac/ Software --- Office & Business Automation --- Consulting GnuPG Fngrprnt:04F7 742B 8F54 C40A E115 26C2 B912 89B0 D2CC E5EA On 2016-06-15 11:03 PM, Alvin Starr via talk wrote:

On 06/15/2016 06:09 PM, Stewart C. Russell via talk wrote:

...

...

I always thought it a shame that the windmill was only used to generate hydrogen for the hybrid fleet. It would have been nice to have it feed the grid It *always* has fed the grid. That hydrogen station coincidentally connected to the grid, and their claim that all the power for their

On 2016-06-15 04:29 PM, Russell Reiter wrote: process came from the turbine was utterly wrong. We tried to get them to change their plaque, but they wouldn't. I think the H₂ station has gone now.

The whole Hydrogen Economy thing kind of fizzled out a few years ago. The coolest and cleverest hydrogen energy thing in the province, though, sits and runs quietly in a nondescript box at Sheppard E & Vic Park. Most people don't know it's there.

The Hydrogen Economy did not quite fizzle so much as changes in government pushed R&D into oil. We installed a fuel cell based backup power system at Victoria and Adelaide. The system worked as billed and life was good till the Sunrise propane explosion changed the rules about getting H2 delivered and Schneider bought APC to leverage the large lead acid battery customer base.

Hydrogenics the manufacturers of the fuel cells is actually doing an OK business in speciality applications like stationary power and indoor power for things like forklifts.

The hydrogen to power process works quite well. The problem is getting hydrogen into a convenient storage format.

--- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

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On Fri, Jun 17, 2016 at 9:00 AM, Lennart Sorensen via talk <talk@gtalug.org> wrote:

On Thu, Jun 16, 2016 at 11:36:09PM -0400, Bob Jonkman via talk wrote:

...

A few (10?) years ago I head a Science Friday show with guest George Olah where he made a strong case for using hydrogen, but storing and transporting it as methanol. It can be used directly (burned), have the hydrogen stripped off and used in hydrogen fuel cells, and there are methanol fuel cells. Methanol can be produced directly from carbon dioxide. But the best part was that since methanol is a liquid, all our current gasoline distribution and storage can be used without a fundamental change in infrastructure. Don't know why this hasn't taken off...

Methanol is very dangerous to have around. If it cathes fire, you can't tell. The fire isn't very hot and the flame is invisible, so you can't see the fire, you barely feel the fire, but it is there.

This is not really something we want in cars that crash into each other.

Race cars and such use it but they also have serious training for recognizing and dealing with the fires.

Ethanol is similar which is why you only get E85, not E100 for sale. The 15% gasoline means you can see the fire if the fuel cathes on fire.

Sorry - - - public safety has become an advanced form of paranoia! All fuels are inherently dangerous, most often in different ways but every form has its specific dangers. How many times have I watched someone light a cigarette after having filled their vehicle with gas. I am getting to the point where to promote travel safety all travel needs to be done only on foot. That would greatly increase safety and would employ a lot more people to get things done. Fuels are so very very dangerous - - - people are hurt and/or killed by their use every year. Imagine all the lives that would be saved we everyone only able to walk! (What we are not comfortable with is most often labeled as dangerous even if it really isn't!) Regards Dee

On Jun 18, 2016, at 14:41, Loui Chang via talk <talk@gtalug.org> wrote:

There's little incentive to replace gasoline as a liquid fuel source since there's still enough supply and it works more or less.

And cheap. Costs much less than a classic bottle of Coca Cola Classic, or Fiji Natural Spring Water. (At Walmart.)

On Wed, Jun 15, 2016 at 3:46 PM, Stewart C. Russell via talk < talk@gtalug.org> wrote:

If you're lucky enough to get a tour of the IESO's HQ, they have a relic of the 25 Hz era on the wall. It's the display clock from the Shortt Synchronome pendulum clock they used to use to regulate the grid. Synchronomes are the most accurate mechanical clock ever made, and one has even been used (briefly, ill-advisedly) as an NTP server.

Now that is a lovely piece of timekeeping. Elegantly simple, and

2.3ppb??! That's a remarkable achievement for any clock from any era, let alone almost 100 years ago. Your average quartz oscillator is five hundred times *less* precise. With that kind of medium-term stability, it could probably be used to discipline a quartz-based clock (with requisite filtering) to generate quite respectable NTP service.

On Wed, Jun 15, 2016 at 06:15:30PM -0400, James Knott via talk wrote:

At work years ago, we had "no break power", where incoming AC ran a motor connected to an alternator and an 8 ton flywheel. When the power failed, a clutch would kick in the diesel, with the flywheel maintaining the power, while starting the diesel. One problem though was the output AC frequency was slightly low and threw off the real time clocks in the computers.

Who built a computer that cared about AC frequency to drive the real time clock? Never heard of anyone doing that. Must have been a large machine given all microcomputers are fed DC from their power supply and have no clue nor care what the AC frequency was. -- Len Sorensen

...

Who built a computer that cared about AC frequency to drive the real time clock? Never heard of anyone doing that.

My first computer, a Poly-88 8080 based system, did (I still have it). <http://www.polymorphic-computers.com/poly88.html>

The transformer used for the linear power supply was tapped, rectified and clamped to feed to an interrupt pin. The interrupt routine would increment a counter in RAM which was accessible for real time calculations.

The Commodore PET and 64 had a 60Hz real-time-interrupt that did a bunch of housekeeping. You could patch your own routines into it, which was really handy. After a particularly nasty bug, that's where I learned about the importance of semaphores in controlling access to shared resources ;) -- Peter Hiscocks Syscomp Electronic Design Limited, Toronto http://www.syscompdesign.com USB Oscilloscope and Waveform Generator 647-839-0325

On Thu, Jun 16, 2016 at 12:53:15PM -0400, Peter Hiscocks via talk wrote:

The Commodore PET and 64 had a 60Hz real-time-interrupt that did a bunch of housekeeping. You could patch your own routines into it, which was really handy.

Wow so the original C64 actually passed 9V AC on a pair of power supply pins for the clock, while later models had an onboard crystal. I didn't know that. That would make doing a replacement power supply a bit tricky.

After a particularly nasty bug, that's where I learned about the importance of semaphores in controlling access to shared resources ;)

Good lesseon to learn early. -- Len Sorensen

On 06/16/16 15:50, Lennart Sorensen via talk wrote:

On Thu, Jun 16, 2016 at 11:55:12AM -0400, Scott Allen wrote:

...

My first computer, a Poly-88 8080 based system, did (I still have it). <http://www.polymorphic-computers.com/poly88.html>

OK, certainly a long time ago.

...

The transformer used for the linear power supply was tapped, rectified and clamped to feed to an interrupt pin. The interrupt routine would increment a counter in RAM which was accessible for real time calculations.

That's neat.

You know of course that the grid frequency is only approximately 60.00 hz. For example, it was 59.97 hz on Friday at around 5 PM. I have heard rumors that the generators spin the grid up to above 60 hz in the early morning hours to compensate for the drift, but I don't know if thats a fact. I often see the grid at 60.01 hz, in the middle of the day though. -- Michael Galea

On Jun 18, 2016, at 23:12, James Knott via talk <talk@gtalug.org> wrote:

On 06/18/2016 07:58 PM, Michael Galea via talk wrote:

...

You know of course that the grid frequency is only approximately 60.00 hz. For example, it was 59.97 hz on Friday at around 5 PM. I have heard rumors that the generators spin the grid up to above 60 hz in the early morning hours to compensate for the drift, but I don't know if thats a fact. I often see the grid at 60.01 hz, in the middle of the day though.

That's true over the short term, but long term accuracy is very good.

Yes, because the power plant frequently advances and retards the frequency slightly so that the average is exactly 60Hz. That makes synchro clocks highly accurate. IIRC, the German train station clocks are synchronized that way. (50Hz).

On Sat, Jun 18, 2016 at 07:58:10PM -0400, Michael Galea wrote:

You know of course that the grid frequency is only approximately 60.00 hz. For example, it was 59.97 hz on Friday at around 5 PM. I have heard rumors that the generators spin the grid up to above 60 hz in the early morning hours to compensate for the drift, but I don't know if thats a fact. I often see the grid at 60.01 hz, in the middle of the day though.

Hmm, my APC SmartUPS just reports 60.0 or 60.2Hz all the time, so I don't think I believe it to be accurate. :) What gismo are you using to measure that? -- Len Sorensen

On Mon, Jun 20, 2016 at 10:54:21AM -0400, Daniel Villarreal wrote:

Wow, by pressing the right-hand button on my APC Back-UPS XS1000, I can see lots of status information, nice!

I also have a Back-UPS XS900, and many years ago it shut down and beeped constantly, if memory servers, and so I replaced the fan, and put it back to work. Now the dual-batteries need to be replaced. I have them out in the garage, but I had taken the specs to my local W*ntronics store and they flatly stated that they would not order what I was specifying, and I refused to buy APC-branded batteries, thinking that I could save lots of money... I should probably pursue this and post the info at my web site.

I recently took lots of pictures of the new memorial to Nikola Tesla down by the Falls, I need to see about putting those online, as well. If you haven't done so, I highly recommend reading "The Man Who Invented The Twentieth Century : Nikola Tesla, Forgotten Genius Of Electricity," by Robert Lomas.

Hmm this might be a helpful place (keele and steeles): http://excessups.ca/apc-back-ups-xs-900-900va-bx900r-battery They even have refurbishes APC SU1500 for $250, which I think is tempting. I could use one more of those. -- Len Sorensen

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Daniel writes:

That's got to be a rough gig, APC trying to get people to upgrade their equipment

Perhaps not as bad as you think. Most places that need UPSes aren't going to be downsizing their requirements, so having a trade-up program will get those customers buying more APC equipment rather than going to the competition. I've done that -- during a server consolidation project we traded in 16 BackUPS units for one Matrix3000 unit (with additional $$$). We might have gone to one of the other vendors, but this way we avoided paying a disposal fee for the BackUPSes, and got a slight price break on the Matrix3000 too. - --Bob. On 2016-06-20 01:35 PM, Daniel Villarreal via talk wrote:

On 06/20/2016 11:50 AM, Lennart Sorensen wrote:

...

On Mon, Jun 20, 2016 at 10:54:21AM -0400, Daniel Villarreal wrote:

...

Wow, by pressing the right-hand button on my APC Back-UPS XS1000, I can see lots of status information, nice!

... Back-UPS XS900... replaced the fan... Now the dual-batteries need to be replaced... I refused to buy APC-branded batteries, thinking that I could save lots of money...

...

Hmm this might be a helpful place (keele and steeles): http://excessups.ca/apc-back-ups-xs-900-900va-bx900r-battery

After researching for RBC5 units and Vision CP 1270, both here and in the U.S.A., your solution (CAD $45.99 + Ground CAD $12.50, or free pick-up in North York) appears to be the best for me, Thank you.

For baseline comparison, APC wants 99.99 for replacement battery unit.

At APC's site, for selecting battery, and also for potential trade-up, one goes to http://www.apc.com/ca/en/support/index.jsp BATTERY REPLACEMENT FINDER

...

They even have refurbishes APC SU1500 for $250, which I think is tempting. I could use one more of those.

"APC Trade-UPS is a 1-phase UPS program that offers new and existing customers the ability to trade in older battery backup units for the most up-to-date 1-phase power protection models at discounted prices."

For the APC Power-Saving Back-UPS Pro 700 (BR700G) the Trade-up discount looks to be about 20%, but that's probably a toy to you.

SU1500RMX155 and SU1500RMXLX157 are discontinued at APC, hmm. Assuming there's a newer, more-updated model, would there be a reason to upgrade?

That's got to be a rough gig, APC trying to get people to upgrade their equipment.

--- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 06/20/2016 01:05 PM, Bob Jonkman wrote:

... Sayal (in Burlington) last week I found they have a whole table of third-party UPS batteries! I need to make a trip there to fix up a bunch of UPSes I have laying around...

There's a Sayal in Cambridge too, so I suspect there may be one local to Niagara Falls as well.

--Bob.

Thanks! http://sayal.com/zinc/zinc_contactus.asp#TOR Unfortunately they're not near the Falls, but maybe I should consider making another road trip... - -- Daniel Villarreal PGP key 2F6E 0DC3 85E2 5EC0 DA03 3F5B F251 8938 A83E 7B49 https://pgp.mit.edu/pks/lookup?op=get&search=0xF2518938A83E7B49 -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJXaC3hAAoJEPJRiTioPntJFB8IAInvcInrFRJlEEwtgBpz2vGK Raedwg5Zr2wQzAUQ63P6QmKzKT1uzq1MgVq4Oq3obHu0Q3jAD9g2QsiSQD0EY+Nu nlqPcPoPqISOA6tDzXl1k6Ta6eOUVZ7f6rjWHKKVW0VyJ2DsolWmjpbT0I7mhRd1 roOzmQZsgL0M2/98om3hrmhQT2OGluPvMYiRnJuOulkmBwE1cQlxfLdZT3EN0brF B2sPQ/MUYwoOj2WpMSwkHt2AqOJDnPCMZ+4jVmnCb7phkWH5d02TLfMWl7zlylWP qRzeGWiiLxiaqQE+kcFarJPIpnZ+aPt+xoJzRTAWUjGm5CVlqq+B7xLxNe75ZSw= =ZTlO -----END PGP SIGNATURE-----

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256

There are plenty of battery suppliers that have what you need. I recently bought a couple from Sayal.

I'll check 'em out, thanks to you and Bob for letting me know about them . - -- Daniel Villarreal PGP key 2F6E 0DC3 85E2 5EC0 DA03 3F5B F251 8938 A83E 7B49 https://pgp.mit.edu/pks/lookup?op=get&search=0xF2518938A83E7B49 -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJXaC4/AAoJEPJRiTioPntJXzcH/RPKbVVsoxRHk2PE0/gPOTgd h4fle7UdzpHmfpZDDJOf9Qz9ib2H4TWVutvVmxnnDch+walwqHI93HlCFoY9P0P6 7qEuoRCDj2g05DSKJtPzd0KTHtjnFCm2uPXTfLYwCcXbvY6ND0J4qJ2LGY3LOVL7 h5ouHNU9XbEeYZROlI6CuQdsaVCZNgKvA8tKvVds/85EYnNv9nmOXRYkbjqxSmbX IcrUgT5BFBdrpmCjHe4vKJq8669yOHVeFHrxoIi1KSyVkvNeff8aQ8B46/gjJ+2L YXbH+ALVzmqq9jy5r1icnlQT0rrAJPkD6K7tuZjzm8wk43+FRUB/4XspQAeC5Qc= =Q66L -----END PGP SIGNATURE-----

On 20 June 2016 at 10:21, Lennart Sorensen via talk <talk@gtalug.org> wrote:

On Sat, Jun 18, 2016 at 07:58:10PM -0400, Michael Galea wrote:

...

You know of course that the grid frequency is only approximately 60.00 hz. For example, it was 59.97 hz on Friday at around 5 PM. I have heard rumors that the generators spin the grid up to above 60 hz in the early morning hours to compensate for the drift, but I don't know if thats a fact. I often see the grid at 60.01 hz, in the middle of the day though.

Hmm, my APC SmartUPS just reports 60.0 or 60.2Hz all the time, so I don't think I believe it to be accurate. :)

What gismo are you using to measure that?

Interesting if the synchronization has gotten lost. For quite a long time, electric clocks were often synchronized based on the 60hz; apparently the Hammond Clocks were from the same Hammond more noted for producing organs, which apparently also used power line frequency stability to stay in pitch... <https://en.wikipedia.org/wiki/Hammond_organ> In the early days of quartz crystal clocks, they did *not* give as good stability as the "beats" provided by the 60hz of the power grid. It seems interesting if the power grids have decided to ignore this. While the clock application has become much less relevant, I would imagine it easier to maintain exact cadence today, with there being more precise clocks. -- When confronted by a difficult problem, solve it by reducing it to the question, "How would the Lone Ranger handle this?"

On 06/20/16 10:21, Lennart Sorensen wrote:

On Sat, Jun 18, 2016 at 07:58:10PM -0400, Michael Galea wrote:

...

You know of course that the grid frequency is only approximately 60.00 hz. For example, it was 59.97 hz on Friday at around 5 PM. I have heard rumors that the generators spin the grid up to above 60 hz in the early morning hours to compensate for the drift, but I don't know if thats a fact. I often see the grid at 60.01 hz, in the middle of the day though.

Hmm, my APC SmartUPS just reports 60.0 or 60.2Hz all the time, so I don't think I believe it to be accurate. :)

What gismo are you using to measure that?

The device I'm using are twin SEL751A automation relays from Schweitzer Engineering laboratories. Both give me pretty much the same readings, and I have no reason to doubt them. They are microprocessor based devices with good sampling rates and high accuracy. When I say 60.XX, its me thats truncating the digits (not the SEL).. Someone remarked that the accuracy of 60 hz is good, and that over-frequencies would cancel under-frequencies. I would really doubt that they could do that to any great degree of accuracy. The grid is the largest machine on Earth, and there is more than just a single generator. -- Michael Galea

On 06/20/2016 10:29 PM, Peter Renzland via talk wrote:

...

On Jun 20, 2016, at 20:31, Michael Galea via talk <talk@gtalug.org> wrote: Someone remarked that the accuracy of 60 hz is good, and that over-frequencies would cancel under-frequencies. I would really doubt that they could do that to any great degree of accuracy. The grid is the largest machine on Earth, and there is more than just a single generator. https://en.wikipedia.org/wiki/Utility_frequency#Long-term_stability_and_cloc...

https://www.ospe.on.ca/public/documents/presentations/electrical-grid-part-1... around slide 40. It does not give a specific number for the "dead band" -- Alvin Starr || voice: (905)513-7688 Netvel Inc. || Cell: (416)806-0133 alvin@netvel.net ||

On Wed, Jun 22, 2016 at 10:31:28AM -0400, Michael Galea via talk wrote:

Out of interest, here are the frequencies the grid had each minute in the last 1-2 days. # grep "FREQ value 59\.94" /tmp/MGC* |wc -l 0 # grep "FREQ value 59\.95" /tmp/MGC* |wc -l 16 # grep "FREQ value 59\.96" /tmp/MGC* |wc -l 99 # grep "FREQ value 59\.97" /tmp/MGC* |wc -l 282 # grep "FREQ value 59\.98" /tmp/MGC* |wc -l 464 # grep "FREQ value 59\.99" /tmp/MGC* |wc -l 459 # grep "FREQ value 60\.00" /tmp/MGC* |wc -l 385 # grep "FREQ value 60\.01" /tmp/MGC* |wc -l 302 # grep "FREQ value 60\.02" /tmp/MGC* |wc -l 144 # grep "FREQ value 60\.03" /tmp/MGC* |wc -l 68 # grep "FREQ value 60\.04" /tmp/MGC* |wc -l 3 # grep "FREQ value 60\.05" /tmp/MGC* |wc -l 0

So an average of 59.991435 for that sampling period. -- Len Sorensen

On 2016-06-22 17:46, D. Hugh Redelmeier via talk wrote:

Remember, he truncated the values (grep does not round).

My best guess: the average of the readings would be from a distribution centred on 59.996435 (0.005 larger than Lennart calculated). It could be as low as 59.991435 or as high as 60.991434, assuming six digits of precision in the fraction. I know nothing about accuracy of the device.

Summary: the 60Hz hypothesis is not excluded by the evidence. Far from it.

P.S. "grep -c" eliminates the need for "wc -l".

and sort/uniq eliminate even more: cat /tmp/MGC|sort -n |uniq -c 16 FREQ value 59.95 99 FREQ value 59.96 282 FREQ value 59.97 464 FREQ value 59.98 459 FREQ value 59.99 385 FREQ value 60.00 302 FREQ value 60.01 144 FREQ value 60.02 68 FREQ value 60.03 3 FREQ value 60.04

On 06/22/2016 04:35 PM, Alvin Starr via talk wrote:

Get out your 6+ digit frequency counter and then run the tests.

6 digits at 60 Hz will take a while. ;-)

On 06/22/2016 07:39 PM, Michael Galea via talk wrote:

If I really needed to know the answer to the question of "how much out", I would get ask the PLC to just count cycles and send me the count with a timestamp. That would tell.

And how accurate is the PLC? Typical CPU clock crystals aren't that accurate.

On 06/22/2016 07:39 PM, Michael Galea wrote:

On 06/22/16 16:35, Alvin Starr via talk wrote:

...

On 06/22/2016 01:25 PM, Jamon Camisso via talk wrote:

...

On 2016-06-22 17:46, D. Hugh Redelmeier via talk wrote:

...

Remember, he truncated the values (grep does not round).

My best guess: the average of the readings would be from a distribution centred on 59.996435 (0.005 larger than Lennart calculated). It could be as low as 59.991435 or as high as 60.991434, assuming six digits of precision in the fraction. I know nothing about accuracy of the device.

[snip]

No, the device is not a UPS. It is a PLC that measures voltages, currents, real and reactive power of a 3-phase service. It provides me the results as IEEE754 32-bit floating point numbers. It's me that truncates to 2 digits.

The data will be collected with an analogue to digital converter. There are a number of different A-D converter technologies that can be used but each technique will affect your accuracy. It is possible that the A-D converters are 32 bit but more likely they are somewhere between 8 and 24 bits. All the A-D converters I know of will give an integer as the result so the floating point comes from the post processing. Then there is the sampling frequency. This will affect the reliability of the frequency if the A-D conversion is used to calculate the frequency. So the accuracy of the measuring system needs to be taken into account when you are using it to measure some other system.

You know I'm sorry I ever implied that the grid wasn't long term accurate at 60 Hz! What I should have said was that in the short term the grid could be quite off 60 Hz but over the longer term it could average out.

The problem is that the grid needs to be short term synchronized because if 2 power sources are providing power and they get slightly out of sync then VERY BAD things happen. So a 0.01 drift from 60Hz will after 50 cycles be out of phase and at all the power from 1 source will sucked up by the other source and the grid will collapse. 50 cycles is just about 1 second of drift but long before that second elapses the grid would have collapsed. The point is that the power sources need to be VERY accurate over the short term. So Pickering needs to be exactly in phase with Bruce and with Niagara and so on. Over the long term they can slightly adjust their phase to make sure they are in sync but if the frequency drifts in the short term then the grid ends up losing power to generator and power-line losses. That being said any single cycle can be wildly off from 60Hz but that will be because of local loading or switching transients.

If I really needed to know the answer to the question of "how much out", I would get ask the PLC to just count cycles and send me the count with a timestamp. That would tell.

-- Alvin Starr || voice: (905)513-7688 Netvel Inc. || Cell: (416)806-0133 alvin@netvel.net ||

On Thu, 23 Jun 2016 11:43:19 -0400 Lennart Sorensen via talk <talk@gtalug.org> wrote:

On Wed, Jun 22, 2016 at 07:39:34PM -0400, Michael Galea via talk wrote:

...

No, the device is not a UPS. It is a PLC that measures voltages, currents, real and reactive power of a 3-phase service. It provides me the results as IEEE754 32-bit floating point numbers. It's me that truncates to 2 digits. You know I'm sorry I ever implied that the grid wasn't long term accurate at 60 Hz! What I should have said was that in the short term the grid could be quite off 60 Hz but over the longer term it could average out. If I really needed to know the answer to the question of "how much out", I would get ask the PLC to just count cycles and send me the count with a timestamp. That would tell. Well wikipedia claims the grid can be off by up to 10 seconds in north america on this side of the continent. The west and texas allow a lot less. So it can certainly be a bit off for quite a while.

this is a very interesting thread, i frequently ponder personal grid timing and other cycles using various oscillations, until the old 40Hz streak lights up (sync) my life

On 06/20/16 22:36, James Knott via talk wrote:

On 06/20/2016 08:31 PM, Michael Galea via talk wrote:

...

Someone remarked that the accuracy of 60 hz is good, and that over-frequencies would cancel under-frequencies. I would really doubt that they could do that to any great degree of accuracy. The grid is the largest machine on Earth, and there is more than just a single generator.

You may have heard of the power grid. With the grid, many generators, in many locations are synchronized with each other. You can be certain this also involves holding the long term frequency stability to 60 Hz.

O.K. So I should have been clear. I really mean that I doubt that the grid achieves an average six sigma frequency of 60.00 Hz more than a few times a day. The thing that I'm not sure that people understand is that if energy withdrawn from the grid does not continuously and exactly balance the power injected into it, _the frequency MUST change_. It fact, since load is continuously changing, so is the frequency. After all, if the grid is runs at 60.01 Hz for an hour (and it does) than it is one part on 6000 off, or about 1/2 a second. That's hardly accurate. At Siemens we achieved 100 nSec accuracy on our IEEE1588 systems and the last time I looked the IEEE was trying to close in on 10 nS. I also have heard of the power grid, being a microgrid designer and all.

--- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

-- Michael Galea

On 2016-06-20 17:15, Kevin Cozens via talk wrote:

On 16-06-18 07:58 PM, Michael Galea via talk wrote:

...

You know of course that the grid frequency is only approximately 60.00 hz.

The short term accuracy of the grid frequency is poor. At any given moment in time will be close to 60Hz but may not be exactly 60Hz. On the other hand it has very good long term accuracy.

Someone shared this series of videos about emulating AC syncing between generators a while back: https://www.youtube.com/watch?v=RT1ySBc-Bls Having watched that particular video, and seeing how out of phase appears as a load to the other system was one of those lightbulb moments for me. As someone who doesn't have any electrical knowledge beyond basic circuitry, I found it worth watching the whole set of videos again. Cheers, Jamon

On Thu, Jun 16, 2016 at 11:55:53AM -0400, James Knott via talk wrote:

Data General Nova & Eclipse computers had a choice of AC power or various clock rates derived from a crystal. The crystal wasn't all that accurate, but normally AC is.

It would be pretty accurate for sure.

The Data General Nova predates microprocessors. It was first build around 1969, IIRC. The Eclipse, while a later generation, used the same basic I/O board, which included the RTC circuits, along with serial port for the console and ports for the paper tape punch & reader.

Yeah that would be old enough to such a thing.

Incidentally, one thing I did was modify those boards from 20 mA current loop to RS-232 for the console and also replaced the fixed crystal serial port clock (you had to change the crystal to change speeds) with a baud rate generator chip that used a colour burst crystal to generate a variety of baud rates. With the 2 mods, those boards moved from 110 b/s Teletypes, to 9600 b/s CRT terminals for the console.

That's a nice improvement. -- Len Sorensen

On 06/14/2016 09:56 PM, phiscock@ee.ryerson.ca wrote:

...

Modern motor controllers can be quite tolerant of significant voltage variation. However, I doubt they're changing the voltage. I'm not a power systems engineer, but it could be that changing the supply voltage would be a matter of changing taps on a transformer.

That would depend on what they have for a power supply. Back when electric streetcars first appeared, they had DC generators. Then AC with motor/generators and later rectifiers, but not much else.

As for flag day - I remember as a kid when there was a changeover to 60Hz in the hydro system. (Was it 20Hz before that? Something much lower.) Anyway, every electric motor in the house had to be changed. Must have cost a fortune.

P.

It was 25 Hz and people didn't have as many appliances back then. Also, in those days, many appliances could run off various frequencies or even DC. Of course, it didn't matter with light bulbs and heaters.

Sent from mobile. On Jun 14, 2016 9:56 PM, "Peter Hiscocks via talk" <talk@gtalug.org> wrote:

...

Modern motor controllers can be quite tolerant of significant voltage variation. However, I doubt they're changing the voltage.

I'm not a power systems engineer, but it could be that changing the supply voltage would be a matter of changing taps on a transformer.

As for flag day - I remember as a kid when there was a changeover to 60Hz in the hydro system. (Was it 20Hz before that? Something much lower.) Anyway, every electric motor in the house had to be changed. Must have cost a fortune.

Had another power out at my building. Just long enough to flip a few switches. The TTC line is hot now so that's probably not it. Although they did say they were going to run a streetcar on it soon. I think this one is probably the result of seasonal switching as they leg out the grid at the CNE grounds for the Indy etc... As the uuid corruptions I experience only seem to affect the secondary disk, I just mount it as needed. I get a SSRT error 16 on the unmounted ATA3 but the system fscks and boots without having to force it manually. I've popped several previous motherboard living here, but the drives seem to survive and I kind of like the view down ft Roulle st and watching the windmill. I resist the temptation to attribute any of the electrical anomalies I have experienced to it's operations, but it does get a little eerie when the thing is pointed right at you and something happens. :-)

P.

-- Peter Hiscocks Syscomp Electronic Design Limited, Toronto http://www.syscompdesign.com USB Oscilloscope and Waveform Generator 647-839-0325

--- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk

On 06/15/2016 10:11 AM, Lennart Sorensen wrote:

Apparently it was from 25Hz to 60Hz in the late 1950s.

I believe it was early '50s, as my parents were living in Toronto when it happened.

Its not that you would need to put in heaver lines for higher voltage but a close to 50% increase in voltage may make you replace all the insulators

<snip> that were rated for 600V with ones rates for 750V. Staff told me the lines themselves were old and needed replacing, notwithstanding any planned voltage increase.

I would expect the motors on the new cars would be based on AC motors

which is the predominant motor type in electric automobiles but with something as big as a train the rules for motor choice may be different.

With AC motors the control electronics would have to handle the voltage variations but its doable.

-- Alvin Starr || voice: (905)513-7688 Netvel Inc. || Cell: (416)806-0133 alvin@netvel.net ||

On Tue, Jun 14, 2016 at 02:58:49PM -0400, Russell Reiter via talk wrote:

You don't think that the TTC might be forward planning for 750V all around? Remember it was TTC staff I spoke to who told me the change was to accommodate higher voltage.

Well according to the published documents, the change is to handle higher current, not a change in voltage. Also the changes are to make the system pantograph friendly since they want to switch entirely to that. The new line with 750V will be double ended trains, just as the subway trains are, unlike the streetcars running on the existing network. Changing the voltage is just a huge hassle since you have to do a flag day, where every streetcar and transformer and any associated gear is all simultaniously swapped out. That's painful, and the slight current drop by going to 750V is unlikely to be worth it, especially since they won't be sharing trains with the new line anyhow. Since they had to upgrade the overhead wire anyhow for pantographs, going to a bigger wire gauge is much simpler than trying to do a swap out of a bunch of other equipment that can't be done in stages. -- Len Sorensen

On Tue, Jun 14, 2016 at 04:19:24PM -0400, Russell Reiter via talk wrote:

Where does it say more amps and not more volts? I'm going by what the guys doing the work told me.

It says increased wire thickness.

I mean it is possible they were wrong but it is just as possible the documentation you refer to is wrong.

Maybe they are going to increase voltage and current together. Line by line as the new equipment is deployed.

However staff did say the new cars operate on a higher voltage. They can't be wrong about that, it's their job to know these things.

A lot of people say voltage when they mean power or current. The new cars need 50% more current, they still run 600V. Without the extra current, they can't run the A/C on them apparently. So yes, they very much can be wrong about that. Or at least they are wrong in what they say about it. Certainly increasing the gauge is to handle more current. Voltage increases do not require wire changes, but could need insulator changes. So while technically possible to incrase voltage in the future, I highly doubt it will happen. At least in the past the subway shared some substations with the streetcar network and hence they had to be the same 600V, although that probably isn't being done anymore. Still, upgrading the substations to a new voltage is not cheap and you have the issue of how to schedule the upgrades in segments so that you don't get different voltages connected together. Leaving the voltage as it is, means the existing equipment can stay with the new wires, and old trolleypoll cars can still be run on the system, at least until the day they get rid of the intersection equipment needed by the trolleypoles (which they appear to plan to do, to reduce maintenance costs). -- Len Sorensen

On Tue, Jun 14, 2016 at 05:57:44PM -0400, Russell Reiter wrote:

I don't doubt it at all. I don't understand not taking advantage of the pantographic ability to carry higher voltage; that is its primary feature.

Actually the primary feature is less maintenance, simpler wiring, and higher speed supported (not that you need that in Toronto streets).

That would be like buying a Porsche and detuning the turbo, just doesn't follow common sense.

Well all that really matters is how much power they can deliver, so voltage * current. Higher voltage means less current, but also bigger insulators needed. It's a tradeoff. Given they already have 600V equipment, sticking with that makes sense. After all increasing the insulator length might not be practical based on the height of the mounting point for the current wires.

On the other hand, for future capacity planning while load balancing the polyphase AC grid we draw that energy from, the advantage of inverting to higher DC voltage under higher demand, does make sense.

Well I am quite sure they are running AC motors, so they would be taking the DC and inverting it to AC and making it whatever voltage they need at the time for the motors. -- Len Sorensen

On Wed, Jun 15, 2016 at 10:04:29AM -0400, D. Hugh Redelmeier via talk wrote:

Most people think 60Hz when they think AC. But I would guess that in a motor AC is timed to the rotation so that commutators (I think that's what they are called) can be eliminated.

Would that AC be 60Hz or would it be variable, matching some function of the motor's current speed?

Completely variable. My understanding is that at least on the freight trains they run the phase just ahead of the current motor position. That means if a wheel slips, it doesn't really speed up and damage the wheel and track, and looses all its power until it regains traction. Allows them to run right to the limit of the available traction unlike the DC motors. So a very simple motor with variable AC generated to match the current requirements of the motor perfectly. -- Len Sorensen

Most people think 60Hz when they think AC. But I would guess that in a motor AC is timed to the rotation so that commutators (I think that's what they are called) can be eliminated.

Would that AC be 60Hz or would it be variable, matching some function of the motor's current speed?

Variable speed AC motors use a variable frequency alternating current. Sometimes you can hear the frequency as it increases when the vehicle is starting. The alternating current creates a rotating magnetic field which 'carries along' the rotor. P. -- Peter Hiscocks Syscomp Electronic Design Limited, Toronto http://www.syscompdesign.com USB Oscilloscope and Waveform Generator 647-839-0325

On 6/15/16, Lennart Sorensen <lsorense@csclub.uwaterloo.ca> wrote:

On Tue, Jun 14, 2016 at 05:57:44PM -0400, Russell Reiter wrote:

...

I don't doubt it at all. I don't understand not taking advantage of the pantographic ability to carry higher voltage; that is its primary feature.

Actually the primary feature is less maintenance, simpler wiring, and higher speed supported (not that you need that in Toronto streets).

Take a look at a trolly pole then a pantograph array and tell me the pantograph needs less maintainence till EOL. You've never heard of a trolly pole monitoring station, there is a pantograph monitoring station though. It's higher voltage capacity that is the reason this form factor takes dominance in overhead wiring. As you said higher vehicle speeds are a moot point in Toronto.

...

That would be like buying a Porsche and detuning the turbo, just doesn't follow common sense.

Well all that really matters is how much power they can deliver, so voltage * current. Higher voltage means less current, but also bigger insulators needed. It's a tradeoff. Given they already have 600V equipment, sticking with that makes sense. After all increasing the insulator length might not be practical based on the height of the mounting point for the current wires.

...

On the other hand, for future capacity planning while load balancing the polyphase AC grid we draw that energy from, the advantage of inverting to higher DC voltage under higher demand, does make sense.

Well I am quite sure they are running AC motors, so they would be taking the DC and inverting it to AC and making it whatever voltage they need at the time for the motors.

So doesn't economy of scale account for the sensibility of starting with a higher DC voltage when part of the load is inverted back to AC for motors? I'm assuming the onboard solid state keeps the input at DC, rectifying it again would go beyond the pale.

-- Len Sorensen

On Wed, Jun 15, 2016 at 11:01:44AM -0400, Russell Reiter via talk wrote:

Take a look at a trolly pole then a pantograph array and tell me the pantograph needs less maintainence till EOL. You've never heard of a trolly pole monitoring station, there is a pantograph monitoring station though. It's higher voltage capacity that is the reason this form factor takes dominance in overhead wiring.

Less maintainance for the power lines, not for the pickup part on the train. The intersection switches needed for trolleypole are complex compared to the trivial wire used with the pantograph. I would be surprised if the train part of the system isn't a bit more complex to maintain with the pantograph. Of course another advantage is that a pantograph doesn't fall off the wire.

As you said higher vehicle speeds are a moot point in Toronto.

Completely.

So doesn't economy of scale account for the sensibility of starting with a higher DC voltage when part of the load is inverted back to AC for motors? I'm assuming the onboard solid state keeps the input at DC, rectifying it again would go beyond the pale.

Well the pantographs needed the larger diameter wire to get a larger contact surface anyhow. Trolleypoles seem much better at making contact around a wire, than the flat contact of the pantograph, well until they fall off. The electicity usage stays pretty much the same no matter what voltage you use, although you have some voltage loss over wire distance, which does give higher voltage a slight benefit, but 750 versus 600 is hardly enough to really matter. It all just comes down to voltage * current in the end. Incraease voltage and you decrease current and get the same result. Maybe the invertor is more efficient with some input voltages than others, but again, it isn't a big voltage difference so probably doesn't matter much. -- Len Sorensen

| From: Alvin Starr via talk <talk@gtalug.org> | Actually the static power loss goes down as the voltage goes up. | | So for example if the streetcar draws 600W at 600V then the current draw is 1A | but at 750V the current draw is 0.8 amps. | The overhead line losses are directly proportional to the current flowing | through them so there would be roughly a 20% decrease in power loss in the | wires. | | With an electrical bill like the TTC must have a 20% decrease would be a | significant amount of money. I'm no EE, but here's my guess. Energy losses are proportional to the square of the current and thus the square of the inverse of the voltage. (750/600)^2 = 1.5625 So they would save more than a third of the transmission losses. I have no idea how much their transmission losses are as a proportion of the electrical power used.

On 06/15/2016 11:45 PM, Alvin Starr via talk wrote:

...

I'm no EE, but here's my guess.

Energy losses are proportional to the square of the current and thus the square of the inverse of the voltage. (750/600)^2 = 1.5625 So they would save more than a third of the transmission losses.

I have no idea how much their transmission losses are as a proportion of the electrical power used. It has been way too long since I have done any power calculations and I believe your right. Looks like its time to brush up on my math skills.

Power is indeed I^2*R, so losses increase with the square of current. However, what's that in relation to the load? One other point that Andy Byford mentioned, when there was that power failure due to fire a while ago, is that most segments are fed from both ends, so you have in effect parallel feeds, with the resistance of each varying with the location of the streetcar along the track. So, the streetcar moves from a point directly below a point where the power is connected to the line, then moves to a point equidistant from 2 points and then to directly below another point. This adds "fun" to the calculations. ;-) Of course, you often have more than one streetcar on a segment.

Most recently the city has replaced the streetcar overhead wires and de-energized and re-energized the system, both times I had spontaneous reboots. One of the TTC engineers told me the new streetcars require more voltage and they are replacing the wires with heavier gauge ones throughout the city.

I wondered what they were doing on Broadview, now I know. This is why we read the TLUG list ;). P. -- Peter Hiscocks Syscomp Electronic Design Limited, Toronto http://www.syscompdesign.com USB Oscilloscope and Waveform Generator 647-839-0325