a motor rated @ 450kW and runs off 400v 3ph 50Hz power supply, how many MW are used in a yr?

Question

when the motor is running 24hrs a day all year long, I am refering to a air compressor

i need the constant output, so to run continously so 78m cubed/min @ 7.5 bar

Answer 1

450 kW x 24 hours x 365 = 3,942,000 kWh or 3,942 MWh

The assumption that the load on the motor is a constant 450 kW. (very unlikely)

Update: The decimal place issue has been corrected.

Answer 2

did you not do Calculus at University, nor have you done Trigonometry

you gave all the sums, just calculate it out

well done MVBIRDO, and with that said, you will still only get 0.8 or 0.9 pf, never unity or seriously hard to get it.

Answer 3

If on constant 450kW for a year total energy used will be:-
Kw times time(in hours) units are kW hours=365 x 24 x 450
= 3942000kW hours = 3942MW.hours
Usualy refered to 3942 million units.
Just because the unit is running does not mean its on full power.The current taken in an electric motor rises automatically with the mechanical load.I'd be surprised if your tptal annual power use was as much as a third of the above calculation,even at that I'd think you were running the mills of satan.

Answer 4

First off the question is meaningless. The phrase "MW per year" makes no sense. Unit-wise, it would be the same thing as mph/year. No doubt the question is trying to ask "how many MEGAWATT-HOURS per year. The failure to understand the difference between watts and watt-hours is one of the commonest on this site and in the popular press: You don't buy kilowatts from the power company -- you buy kW-hours (kWh) -- that is the only billable quantity.

Assuming the problem asks for MWh,

450 kW x 24 hours x 365 = 3,942 kWh, or 3.942 MWh. That is what the user would buy from the utility.

The voltage, phases and frequency are not relevant -- only power X time counts here. Power factor would be relevant in the real world, but is ignored for purposes of this exercise.

Answer 5

Surely air compressors do not run continuously, but are stopped and started as the stored pressure varies?

However, running continuously throughout the year, consumption is 450kWh in an hour, therefore, annual consumption would be 24x365x450/1000MWh.

Answer 6

i failed on exam questions similar to this 3 weeks ago, still got a B tho

Answer 7

3 phase not relevant unless 450 kW per phase
450 times hours in a year is annual consumption
450 x 24 x 365 = 3942 MegaWatts

Above Answer by Thomas is 1000 times low !

All this ignores Inductive correction factors since no details are given.

Answer 8

Surely the idea of an air compressor is to store and compress the air, if the pump must work continuously then you might as well discard the compressor.