Power meter reading question 2

[itsmoked]

I asked a customer to tell me what the typical power consumption of his facility is. He called me to tell me "it averages point five kilowatts".

What??! This is an absurd number for a place filled with dozens of huge machines.

So he sent me this picture:

Sure enough that's what the meter shows. Obviously there's a turn-down ratio from sensors. They even have a place to write down the "multiplier" on the meter but in typical form no one did it.

Is there a standard multiplier for this? 1,000, 100, ??

Keith Cress
kcress -

http://www.flaminsystems.com

 

[davidbeach]

Looks to me like 160.

 

[itsmoked]

!! That's what that 160 means? Is the "C" meaning Calibration?

0.53 x 160 = 84kW

I need to square that with what I think the machines are doing. The air compressor alone is 18kW.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[davidbeach]

800:5 CTs with direct measurement of the voltage. Service is probably between 800A and 1200A.

 

[waross]

That 160 is on a stick on tab. It is covering up the internal connection diagram.
The multiplier is the CT ratio times the PT ratio.
I think that David nailed it.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[scottf]

I can confirm that the "C" sticker is what PG&E uses to indicate a CT is in the meter circuit so as technicians are aware to either short the circuit via test switches or kill the service prior to pulling the meter. And the "160" is the CT multiplier. If there were VTs, there would be a "V" sticker too.

 

[stevenal]

So does the number represent an instantaneous value, or a demand? Suggest looking at a typical bill.

 

[itsmoked]

Thanks much scottf.

stevenal; I believe it's instantaneous as it changes instantly with any load changes.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[stevenal]

Since it's a "smartmeter", there may be lots of data on the PG&E website with charts and graphs of interval data. The customer would need to login to their account.

 

[jraef]

The "C" on the sticker means that the calibrated CT used for the multiplier is on C phase (this is a 3 phase meter). This is also a NEM (Net Electric Meter), meaning that the user has a solar field or other generating capability and the energy shown on the meter display is their NET CONSUMPTION, not peak or instant. It's going to be useless in determining anything about their load profile.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[scottf]

jraef-

What do you mean by "CT used for multiplier is on C phase"? There would be a CT on all phases...all with the same ratio, likely 800:5A.

 

[waross]

That is a 9S meter. It requires 3 CTs, one on each phase.
Those electronic meters typically record all 4 quadrants, and just display two plus demand.
Internally they will be metering and recording Positive kiloWattHours, negative kiloWattHours, leading KVARs and lagging KVARS.
They will display kiloWattHours and lagging KVARs. They will also display demand KW.
Many utilities use a default display of positive kWHrs plus negative kWHrs. The display s what the meter reader reads or the meter transmits to a remote data station.
Normally there is no negative kWHrs. That is only when you are delivering power to the grid.
If some of the old tricks are used to reduce the meter reading such as installing the meter upside down, the reverse power is added to the forward power and the customer still pays the full amount.
The utility may change the programming.
It will be interesting if you are able to tell us what values are displayed on this meter, Keith.
I was having issues with a department store.
A friendly engineer at the utility provided me with a spread sheet on a disk. The infoemation was taken from the meter.
It included maximum and minimum voltage and max/min current per time period as I remember. Powerfactor information was included.
The time period was 15 minutes and the spread sheet covered the previous month. That is complete readings for each 15 minute period for a month.
The cost was supplying my own floppy disk and two litres of Pepsi for the office.



Bill
--------------------
"Why not the best?"
Jimmy Carter