Line voltage spec?

[Open Neutral]

I've always thought it was 240V +/- 10%..

But a HVAC manufacturer is claiming 250V is outside their spec. I'm dubious of any reason besides "We don't want to pay a warranty claim on this.." but thought I'd confirm.

 

[Open Neutral]

Errr "LiNe voltage spec...."

 

[LarryFine]

It depends on their voltage limits and the voltage applied, and how do you or they prove it?

Look at the acceptable voltage range shown on this equipment label as an example:

 

[retirede]

I believe ANSI C84.1 says utility voltage should normally be +-5%. So 252V max.

 

[Open Neutral]

I believe ANSI C84.1 says utility voltage should normally be +-5%. So 252V max.

Thanks. I was not clear on it being the POCO spec vs the gear.
The HVAC nameplate says 253 volts.

I always thought undervoltage was to be avoided on rotating machines as lower voltage begets higher currents and thus more heat.

 

[Hv&Lv]

Thanks. I was not clear on it being the POCO spec vs the gear.
The HVAC nameplate says 253 volts.

I always thought undervoltage was to be avoided on rotating machines as lower voltage begets higher currents and thus more heat.

Higher voltage can have the same heating effect.
The high voltage causes the magnetized portion of the motor to saturate.
The motor then draws excessive current to try to magnetize the iron beyond the practical limits.

 

[Hv&Lv]

I've always thought it was 240V +/- 10%..

But a HVAC manufacturer is claiming 250V is outside their spec. I'm dubious of any reason besides "We don't want to pay a warranty claim on this.." but thought I'd confirm.

 

[steve66]

It says right on the nameplate max voltage 253 volts.

Also, since its utilization equipment, its rating is 230 volts. So 10% is 230 + 23 = 253.

Oh, that's a different label, but yours will still be rated for 230 volts.

Its 10% normally for an applicance rating, and 5% for the utility rating. That way the utility voltage should always be inside the appliance rating voltage.

 

[jaggedben]

I've always thought it was 240V +/- 10%..

But a HVAC manufacturer is claiming 250V is outside their spec. I'm dubious of any reason besides "We don't want to pay a warranty claim on this.." but thought I'd confirm.

Nominal 250V would be outside their spec, but 250V appearing for a while on a 240V nominal service would not be. Otherwise just about every single family home compressor in the country would be installed out of spec. This is just one of those things where the traditional labeling is misleading for obscure reasons.

 

[Open Neutral]

Thought I'd follow up to this thread I started. I later found <https://forums.mikeholt.com/threads/voltage-ratings-110-115-120-220-230-240-or-440-460-480.2563412/> which was enlightening; thanks Jrael.

I used a TrueRMS Fluke and found 253VAC at no load. Specs on the compressors:

MCC​	RLA​	FLA​	LRA* {With softstart}​
41.2​	26.4​	134​	47​

The above are per compressor. With both running, it's still 253V. A fellow EE who has served on PSE's Citizens Advisory committees tells me their pad mount transformers are fixed, no taps to change. Imagery from its installation seem to confirm that.

So does the POCO have an obligation to lower the line voltage, and if yes, how?

 

[Open Neutral]

Sorry forgot the link:

 

[don_resqcapt19]

View attachment 2563839

In Illinois the service voltages are set by the rules of the Illinois Commerce Commission and they differ from the service voltages shown in that table.

Illinois Commerce Commission JCAR rules
Section 410.300 Voltage Regulation
Standard voltage. Each entity supplying electrical energy for general use shall adopt a standard service voltage of 120 volts (when measured phase to neutral) and shall maintain the service voltage within the allowable variations from that value at all times.

Allowable voltage variations. For service rendered at the standard service voltage, voltage variations as measured at any customer's point of delivery shall not exceed a maximum of 127 volts nor fall below a minimum of 113 volts for periods longer than two minutes in each instance. For service rendered at voltages other than the standard voltage value, voltage variations as measured at any customer's point of delivery shall not exceed 10% above or below the service voltage for a longer period than two minutes in each instance.

 

[Hv&Lv]

In Illinois the service voltages are set by the rules of the Illinois Commerce Commission and they differ from the service voltages shown in that table.

Yeah, they have a tightened range B for two minutes.
Ansi C84.1
what I posted is range A and is used to show utilization, nema tolerance, etc..

 

[Jraef]

Remember, the utility distribution voltage level and allowance is measured at the SERVICE ENTRANCE, but is expected to drop in the distance to the utilization point, i.e. where the load actually connects. So before reacting to a perceived over voltage issue, take a measurement AT the point if use, under load if possible. I seriously doubt you will read 253VAC at the point of use.

 

[Open Neutral]

Remember, the utility distribution voltage level and allowance is measured at the SERVICE ENTRANCE, but is expected to drop in the distance to the utilization point, i.e. where the load actually connects. So before reacting to a perceived over voltage issue, take a measurement AT the point if use, under load if possible. I seriously doubt you will read 253VAC at the point of use.

I had serious doubts as well.

But:

The house's 100 KVA xfmr (in link above) is about 50-60 ft away from the CT box/Main disconnect. That path is parallel 350MCM.

The Mech Room 200A subpanel is ~100 ft from the Elec. Closet. {Don't know size, alas. But the EC didn't skimp.}

And I did measure at the contactors while under load. I did it 2-3 times because I didn't believe it didn't droop. Granted, the Fluke TRMS meter was 3 digits so nothing after the decimal point, but...

 

[Hv&Lv]

So does the POCO have an obligation to lower the line voltage, and if yes, how?

Line regulators.

Also it wouldn't hurt to confirm the XF primary voltage.
Ex. Say a transformers primary voltage is 7200. Thats a 30 TTR.
The actual primary voltage is 7620. That should be 31.75 TTR
put the 7200V (30 TTR) XF on a 7620 line, you have 254 volts
(7620/30=254)

I’ve seen it happen before on another system..

 

[MD Automation]

...put the 7200V (30 TTR) XF on a 7620 line, you have 254 volts...

Wow, would not have thought of that, but the math don't lie!

How would the average person go about finding their primary voltage? I know my little single phase overhead is 7620 to gnd, only because I have talked to local linemen and seen the label on the transformer up on my pole. Maybe if the OP can look at his pad mounted nameplate to see if it's listed at 7200 and find another xfmr nearby listed for 7620??

 

[Open Neutral]

Line regulators.

Also it wouldn't hurt to confirm the XF primary voltage.
....

I’ve seen it happen before on another system..

The EE I mentioned said PSE's are all 32 TTR. We'll look into that, but I think I'll skip trying to measure the primary with that Fluke.

It's annoying that pad xfmrs never seem to have external dataplates.

 

[MD Automation]

I think I'll skip trying to measure the primary with that Fluke...

the Fluke TRMS meter was 3 digits so nothing after the decimal point

Good idea!

If you tried to measure with the Fluke, afterwards you wouldn't have to worry about anything before the decimal point either

 

[Open Neutral]

At the time, I was a few thousand miles away, but when I saw this image.....

It's a few hundred feed of boring upstream of our project's {previously seen} 100 KVA and shows the initial connection being made to light up ours. What bothers me greatly is the PPE, or rather lack of it. While NOT my area, I'd have assumed at the very least, full face masks and gauntlets would have been ...fashionable...

ps: no-charge extra: the CT cabinet & our main.