Demand ???

[sundowner]

Was asked today what exactly the demand scale on an old Sangamo KWH meter really read. I had to stop and think, its been a long time since I've had to explain this one.

Any help guys

S

 

[barbeer]

Power consumption?:roll:

 

[bob]

Was asked today what exactly the demand scale on an old Sangamo KWH meter really read. I had to stop and think, its been a long time since I've had to explain this one.

Any help guys

S

The demand is the max kw or kva that occurs over a given time span.
Usually its 15 minutes or 30 minutes or what ever time the test requires.

 

[sundowner]

If the demand is the power consumption, or the max KW over time, then what is the difference between KWH and my demand dial??

Would'nt it be redundant? Am I thinking of this the right way: the max amount of power that went "through" the meter at any given time, the maximum one time largest draw on the power supply. If this is correct, why would I want to know this if I already have the KWH for billing purposes.

Any more ideas guys ??

S

 

[mdshunk]

The demand counter gets reset every month by the meter reader. It has a seal tag or small padlock on the end of the meter glass. It's the highest 15 minute period that month.

 

[rattus]

If the demand is the power consumption, or the max KW over time, then what is the difference between KWH and my demand dial??

Would'nt it be redundant? Am I thinking of this the right way: the max amount of power that went "through" the meter at any given time, the maximum one time largest draw on the power supply. If this is correct, why would I want to know this if I already have the KWH for billing purposes.

Any more ideas guys ??

S

Demand is measured in KW which are units of power. This is, the maximum power the customer is demanding. The poco distribution system must be able to supply this max power, and that costs money.

Consumption is measured in KWH which are units of energy. That is, the total energy used by the customer over a billing period.

 

[peter d]

So in other words, we pay for true power, and the poco pays for the losses associated with apparent power?

Of course, we ultimately pay for the cost of loss as that is factored into the electricity rates.

 

[ron]

I'm not sure of that particular meter model, but in many areas, the utility takes a 15 minute increment of kWH and multiplies it by 4 to get what gets called kW demand. It is the "penalty" for loading their utility equipment.

BTW, I always thought that it was the maximum value read at any given instant, but I was recently corrected by Con Edison of NYC.

 

[rattus]

So in other words, we pay for true power, and the poco pays for the losses associated with apparent power?

Of course, we ultimately pay for the cost of loss as that is factored into the electricity rates.

We pay for ENERGY measured in KWH.

We pay a surcharge for max POWER measured in KW.

We may pay a PF penalty as well to offset the poco's cost of delivering APPARENT power measured in KVA.

Gotta distinguish between the units of energy and power.

It has been nearly 60 years since I was a teenage clerk auditing utility bills with pencil and paper. I couldn't even spell PF then.

 

[rattus]

I'm not sure of that particular meter model, but in many areas, the utility takes a 15 minute increment of kWH and multiplies it by 4 to get what gets called kW demand. It is the "penalty" for loading their utility equipment.

BTW, I always thought that it was the maximum value read at any given instant, but I was recently corrected by Con Edison of NYC.

Older systems used a circular chart which recorded the MINIMUM sustained demand over a 15 min period. This chart was changed monthly and the recording was interpreted by the reader or a clerk at the office.

It would make more sense to compute the MAXIMUM average power (in KW) over a 15 min period, and I think this may be done with modern meters.

 

[rattus]

You've got it, I think:

You've got it, I think:

I'm not sure of that particular meter model, but in many areas, the utility takes a 15 minute increment of kWH and multiplies it by 4 to get what gets called kW demand. It is the "penalty" for loading their utility equipment.

BTW, I always thought that it was the maximum value read at any given instant, but I was recently corrected by Con Edison of NYC.

That makes sense. Measure the energy used in 15 min (KWH), then divide that by 1/4 hour to obtain the average power (KW) over that 15 min period. Then find the period with the maximum average power. Easy with computers.

 

[LawnGuyLandSparky]

I'm not sure of that particular meter model, but in many areas, the utility takes a 15 minute increment of kWH and multiplies it by 4 to get what gets called kW demand. It is the "penalty" for loading their utility equipment.

BTW, I always thought that it was the maximum value read at any given instant, but I was recently corrected by Con Edison of NYC.

To combat this, some larger buildings in NYC have found that running their own gensets to power elevators and/or air conditioning systems was cheaper, and in response ConEd is suing these customers, claiming only the public utility is entitled to provide electrical power.