bad power very VERY bad power! dont want server damage

[kaboom]

Re: bad power very VERY bad power! dont want server damage

quick question, is 135v high for this center-tap nonsense?

At home with a split phase service? Then yes. If the opposite leg is ~105V, you've got an open service neutral. Your CATV/gas pipe (dielectric union?)/telco ground is balancing things out.

[cheapie]

Re: bad power very VERY bad power! dont want server damage

quick question, is 135v high for this center-tap nonsense?

Yes... try asking your neighbors if you can take some measurements from their outlets to see if it's a problem with your house (like a high-resistance neutral, which will cause high voltages on some circuits and low on others) or if it's something that the power company is doing wrong.

The way that the American system works is that the electrical system is basically a series-parallel 240V system, with a center tap on the transformer's secondary (called "neutral" and is bonded to ground, otherwise it would be a floating system) to help equalize any imbalances between the two sides of the load. If the neutral goes open, then the power cannot even out between the two halves. Whichever side has the lower resistance (higher load) gets a lower voltage drop across it, thanks to Ohm's law.

If you have your own transformer (as in the power company's transformer is only powering your house), it wouldn't be hard to convert your house to a straight 240V system. You would just have to bond a phase to ground, and disconnect the neutral. If you share a transformer, an isolation transformer can be used for this.

I don't get why we even have this system in the first place, really. I wish we had a 3-phase, 240V-to-ground system like so many other countries.

Hopefully that all made sense.

[goontron]

Re: bad power very VERY bad power! dont want server damage

At home with a split phase service? Then yes. If the opposite leg is ~105V, you've got an open service neutral. Your CATV/gas pipe (dielectric union?)/telco ground is balancing things out.

no, all legs at 135v, i live in an apartment building and my neighbors power is like that too. i have checked the return, it in good nick. this all started once the transformer was replaced.

[cheapie]

Re: bad power very VERY bad power! dont want server damage

no, all legs at 135v, i live in an apartment building and my neighbors power is like that too. i have checked the return, it in good nick. this all started once the transformer was replaced.

You could try to see if there's something that the power company could do. Some of those transformers have multiple taps to adjust the output.

Interestingly, the voltage here goes down 2-3V at night. Maybe it's the people using electric heat. There can't be too many, though, as electricity is very expensive here.

[kaboom]

Re: bad power very VERY bad power! dont want server damage

no, all legs at 135v, i live in an apartment building and my neighbors power is like that too.

208Y/120 is a possibility, if it's a largeish building.

Measure between each outside leg of a "dryer" or "range" outlet to neutral or GND. Both legs should be within a volt or two.

i have checked the return, it in good nick. this all started once the transformer was replaced.

You positively cannot tell this from where you are. Multiple panels/apt's, and multiple GEC, CATV, telco(?) parallel bonding paths. The noodle can be flying in the air and things will appear to be balanced.

You must check voltages again. If this were a single service such as on a house, I could tell you how to use a long extension cord as an "extended test lead" and a meter to check FOP between your svc neutral buss and transformer ground. But, again, multiple parallel paths make this difficult.

Notice any lights getting brigher when large appliances, on another leg, kick on? Fridge, washing machine, dishwasher, microwave, for example.

FWIW, 135V AC results in 191V DC on each incoming electro in an SMPS.

[goontron]

Re: bad power very VERY bad power! dont want server damage

208Y/120 is a possibility, if it's a largeish building.

Measure between each outside leg of a "dryer" or "range" outlet to neutral or GND. Both legs should be within a volt or two.




You positively cannot tell this from where you are. Multiple panels/apt's, and multiple GEC, CATV, telco(?) parallel bonding paths. The noodle can be flying in the air and things will appear to be balanced.

You must check voltages again. If this were a single service such as on a house, I could tell you how to use a long extension cord as an "extended test lead" and a meter to check FOP between your svc neutral buss and transformer ground. But, again, multiple parallel paths make this difficult.

Notice any lights getting brigher when large appliances, on another leg, kick on? Fridge, washing machine, dishwasher, microwave, for example.

FWIW, 135V AC results in 191V DC on each incoming electro in an SMPS.

actually i can tell you that return is in good nick, i have been in my panel(zinsco) in the meter room (more zinsco) and at the lines to the pole, it in goood nick.
and we got new manager and new owner so im going to type up a notice about the hazards.

[kaboom]

Re: bad power very VERY bad power! dont want server damage

actually i can tell you that return is in good nick, i have been in my panel(zinsco) in the meter room (more zinsco) and at the lines to the pole, it in goood nick.
and we got new manager and new owner so im going to type up a notice about the hazards.

Have fun.

How many lines? Triplex? Quadplex?

How many transformers? A three-phase bank, or a single large pot?

7620 transformer(s) on a (14400/) 8314 system by mistake? If so, 208, if three phase, will be reading 226. If single phase, your 240 will be almost 270!

[goontron]

Re: bad power very VERY bad power! dont want server damage

its a triplex 2 hots 1 return,(3 phase?), my DMM only reads up to 200vAC.
but you could soon be corrector about return going open, I found the wire support arm broken and leaning on the return connection to the trany with a tree branch leaning on the broken arm

[kaboom]

Re: bad power very VERY bad power! dont want server damage

its a triplex 2 hots 1 return,(3 phase?), my DMM only reads up to 200vAC.
but you could soon be corrector about return going open, I found the wire support arm broken and leaning on the return connection to the trany with a tree branch leaning on the broken arm

What remotely modern DMM only reads to 200V AC?

120/240 single phase or 120/208 single phase, but only if two or three transformers present.

Sounds like the former, though. Old building, old Zinsco junk, old area...

If your electric meters have four tabs, then it's 120/240 1ph. If they're "fifth jaw" meters, then it's 120/208.

Get a long grounded extension cord. Plug it into any outlet in the place. Extend it out to the transformer pole. With meter set to AC volts, measure from the "ground" of the extension cord to the ground going down the side of the pole. I'll bet you get an easy 10V, even with all the parallel paths I mentioned previously.

Don't hesitate to call the POCO (again)!

[goontron]

Re: bad power very VERY bad power! dont want server damage

http://www.controlrepair.com/p29590_...eter-plus.html
only one tranny.
only 4 tabs.
what ground wire? the pole dont have one!
will call the POCO, i dont like the look of the cross arm or the tree leaning on it!

[kaboom]

Re: bad power very VERY bad power! dont want server damage

http://www.controlrepair.com/p29590_...eter-plus.html
only one tranny.
only 4 tabs.

120/240V 1ph

what ground wire? the pole dont have one!

Is the transformer fed phase-to-phase, aka, two primary bushings?

will call the POCO, i dont like the look of the cross arm or the tree leaning on it!

And if the tree ever touches the primary, keep away, as much as you might wanna play...

[goontron]

Re: bad power very VERY bad power! dont want server damage

120/240V 1ph



Is the transformer fed phase-to-phase, aka, two primary bushings?



And if the tree ever touches the primary, keep away, as much as you might wanna play...

it fed phase to phase.
aww, but i know how to play with 50KV safely.

[kaboom]

Re: bad power very VERY bad power! dont want server damage

it fed phase to phase.

Aha- no MGN? Multi-grounded neutral. In areas where soil conductivity is better, we have single bushing cans, naturally fed with a single primary leg. Secondary and primary neutrals are always bonded. As well as POTS and CATV shields. In addition, there are ground rods every so many poles, and always on transformer poles and poles with arrestors.

"Out west," they like to connect transformers' primaries phase to phase, although there is an interesing system in and around San Diego.

4160/2400Y, with a neutral and pots single-phase-fed to neutral, with a 16(?) KV overbuild, whose transformers are of the two-bushing type. I think the 16KV is a wye system, but w/o a neutral from the subs it originates from.

As systems "modernize," POCOs in rocky and sandy areas appear to be mitigating "step potential" issues...

Around where the "smoshers" live, there's an elaborate 21/12KV distribution network. Apparently, once upon a time, cans were fed hot-to-neutral at ~12KV. Now it's phase to phase at 21KV. And the 72KV subtransmission is overbuilt. Which is ultimately derived from 138, 161(?) and 345kV.

PECO does something similar in their service area. Large 138/34.5 and 230/34.5 subs. As well as 500/230/138. Huge subs, just not that many. They run the 34.5KV throughout neighborhoods, ROWs, all over the place. Every few miles, there's a 34.5/4.16KV "modular sub." Like a unit substation, but bigger. Still, otherwise self contained. The 4160/2400 is then stepped down by pole pigs or padmounts for whatever the customer requires. Newer developments and buildings just use the 34.5 directly, with pigs and pads dropping it all the way down to secondary voltage. That's right- 34.5KV->120/240V. Almost frightening if you've never seen it before.

MetEd/FirstEnergy/FirstEnema is more conventional. Like 500/230, then 230/138/69, and multiple 69/13.2KV subs across the area. The 13.2KV is "single-phased" at 7.62KV into single phase TXs to feed houses. Either 13.2/480V or 13.2/208 pads or banks for larger buildings. There are multiple 69 ckts, each serving a given area. But each 69 ckt has multiple tie-ins and switches, as well as the ability, in areas of higher density, to parallel other 69kV ckts. Redundancy.

But what's unique to the MetEd service area is all the old sorta REC stuff. Out along country roads, you'd come across a pole with a huge single-phase transformer on it. These are "stepdowns," taking 13.2kV single phase or 7.62kV down to 4800V. The old 4800 open delta(?) stuff. A trip back in time.
IOW, it is the 13.2 serving as subtransmission for the 4800, just as the 69 does for the 13.2!

Ubiquitous in farming areas. Two bushing transformers, no pole ground, no primary neutral. Two cutouts and two LAs. These are a lot of fun when a leg is lost or backfed down and up thru two stepdowns in 13.2/4.8/13.2 or 7.62/4.8/7.62 fashion. People end up with some stupid 60-80 volts!

aww, but i know how to play with 50KV safely.

Step potential and live trees make things... interesting.

I think I topped myself in that one...

[RJARRRPCGP]

Re: bad power very VERY bad power! dont want server damage

it fed phase to phase.
aww, but i know how to play with 50KV safely.

Spark ignition on a gas engine?

[delaware74b]

Re: bad power very VERY bad power! dont want server damage

As an electrician, I hope I can help fill in the blanks on electrical voltages. 120VAC is typically + or - 10%, so your utility is providing anywhere from 108 to 132 volts and still be 'within their specs'. I have to make my building to allow only a 3% voltage drop on any circuit while under load. Go figure.

I moved from Harrington to Dover area in August and noticed a huge difference in the power quality (or the lack of quality). Delmarva Power tries to run their transformers at 300% capacity. My old service was on OLD copper overhead(uninsulated, green) and I was the last of 14 houses on a 50KVA transformer. As a result, I never saw 120volts. My voltages ranged from 115 on a good day to 107 on a bad day, my main UPS was never happy with that, always correcting a brownout condition.

City of Dover electric is underground, voltages rarely drop below 117 volts, regardless of loading.

Excessive high voltages are not good for incandescent lamps, but 'smart ballasts' used in commercial T8 lighting don't care unless it drops below 108 and don't exceed 305 volts. Some motors won't like it either, but most will actually run cooler at slightly higher voltages.

[ben7]

Re: bad power very VERY bad power! dont want server damage

As an electrician, I hope I can help fill in the blanks on electrical voltages. 120VAC is typically + or - 10%, so your utility is providing anywhere from 108 to 132 volts and still be 'within their specs'. I have to make my building to allow only a 3% voltage drop on any circuit while under load. Go figure.

I moved from Harrington to Dover area in August and noticed a huge difference in the power quality (or the lack of quality). Delmarva Power tries to run their transformers at 300% capacity. My old service was on OLD copper overhead(uninsulated, green) and I was the last of 14 houses on a 50KVA transformer. As a result, I never saw 120volts. My voltages ranged from 115 on a good day to 107 on a bad day, my main UPS was never happy with that, always correcting a brownout condition.

City of Dover electric is underground, voltages rarely drop below 117 volts, regardless of loading.

Excessive high voltages are not good for incandescent lamps, but 'smart ballasts' used in commercial T8 lighting don't care unless it drops below 108 and don't exceed 305 volts. Some motors won't like it either, but most will actually run cooler at slightly higher voltages.

Did that poor, overloaded transformer ever burn out?! 14 houses on a 50kVa transformer ... erm, that is pushing it!

[RJARRRPCGP]

Re: bad power very VERY bad power! dont want server damage

Green Mountain Power in Vermont seems to usually be at 120 for the minimum.

(Seeing 117V and lower is actually scary in Springfield, at least this building, because it means it's on bleeding edge and a circuit breaker trip is right around the corner!)

(Formerly CVPS)
(IIRC, CVPS bought GMP, but the former GMP was not in this region of Vermont and CVPS was renamed to Green Mountain Power!)

It's usually 124V-126V

124V right now, according to my UPS.....

Before July, I found out that one day in 2013, the 10,000 BTU air con, the 5,200 BTU air con, microwave oven and my PC were running on the same circuit! WTF! It tripped when one of the workers was using the microwave oven in our kitchen.
At least roughly 2,500 watts!

[cheapie]

Re: bad power very VERY bad power! dont want server damage

My old service was on OLD copper overhead(uninsulated, green) and I was the last of 14 houses on a 50KVA transformer..

We have the overhead uninsulated lines here, but this is the only house on a 50KVA transformer.

At school, they get 408(?)V 3-phase coming into the building. There are 30KVA transformers scattered throughout the building (about 15 of them) to make 120/240V. I sit next to one in one of my classes. I might have to get a picture of the nameplate. Also, earlier this year, there were problems with the main fuses blowing. They just put in bigger and bigger fuses until they stopped blowing. Strangely, even toward the end of that, when they had an electrician in the building all day, it still took about half an hour to change the fuse.

[delaware74b]

Re: bad power very VERY bad power! dont want server damage

ben7 - I don't know about that transformer..... I moved from Harrington in August. I do know the power in my new location is much more stable and my UPS's haven't been correcting unless I turned the breakers off. I have been doing some electrical repairs/upgrades around the new house.