maximum demand

The formula is:

INFINITE_DEMAND - MINIMUM_DEMAND = MAXIMUM_DEMAND

WOW

With Minimum approaching Infinite Maximum may approach Zero.

∞ - ∞ = ∞ / undefined.

Add up all the connected loads.

<...calculated...>

Almost impossible, for it depends entirely upon how the system is used. There isn't an equation for absolutely everything!

It can be measured with some suitable maximum demand metering device.

For any existential question one should always consider the answer as being 42

C'mon guys. Geez, given that this is most likely a homework problem, at least consider the possibility that a real algebraic answer exists and wait a few minutes to see.

Dear Guest, The calculation would be as follows:

[(60_min/T_int) X kW₁ X t₁/T_int] + [(60_min/T_int) X kW₂ X t₂/T_int] + [(60_min/T_int) X kW₃ X t₃/T_int] +....[(60_min/T_int) X kW_n X t_n/T_int]

Where:

T_int = chosen measurement interval in minutes. Example 5min, 15min, 30min etc.

t₁ + t₂ + . . .t_n = T_int in minutes.

kW₁, kW₂, etc. are the various load values during the interval.

Since the standard interval is 1 hour (60 minutes), the common factor (60_min/T_int) produces the equivalent value to the standard interval. (What it would be if the interval measured were an hour.) 60_min / 60_min = 1, 60_min / 15_min = 4, etc.

Obviously, each kW load value will be constant for an even number of minutes only in theory or a homework setting, so in the real digital world the time factor is adjusted to the sample rate, but the standard is still 1 hour. This standard is set to accommodate kWh/h calculations.

Maximum Demand is calculated by additing all the total load that you have in your plant.

Greetings Simon,

I would agree that one could add up the total load available to draw power, however I don't think I have ever seen an installation with 100% of available load in use at the same time. Peak demand is then by default less than 100% of what you have suggested.

I don't believe I've ever seen a service sized by that total figure either. Typical average usage factors called 'load factors' are applied to the items of the total load available, and the result, shown on the electrical drawings, is the 'expected demand'.

Based on a well applied range of highest and lowest 'load factors', an estimated 'Maximum Demand' can be derived based on what loads are expected to be on at the same time. Add a safety factor, and the service is sized to the next largest standard equipment capacity.

I can state with certainty that many electrical service drops are sized well below the maximum available load. They are sized by experienced estimates of actual peak draw (demand). To do otherwise would be to waste money over-sizing the drops and the distribution equipment.

The math for such estimates is simple addition of the highest expected simultaneous loads in kW for 1 hour (kWh/h). Demand is stated in kW.

The previously stated formula is used by a digital meter to calculate peak demand from measured values.

The method discussed here would be for calculating an 'estimated' peak demand, which will be much less than the total load available.

Regards, CJM

Of course you haven't defined what it is or how many are making the demand.

If it's to do with women then you have no hope of meeting their demand, or any demands to their complete satisfaction. Only took me 30 years to work that out...

Max.demand = Total Connected Load x demand factor