What is the load factor for?

[dahualin]

I have got recent 12 months electric bills for a facility to evalucate the existing load. The biggest peak demand is 1373 KW and Load Factor is 71.07%. I don't know the power factor. What is real demand in KVA? Do I have to use peak demand 1373KW divided by the load factor 71.07% to get peak demand in KVA?

I googled online that load factor is delivered power divided by design power at certain period time. That realy confused me.

Any thought is appreciated.

 

[charlie b]

I Googled online that load factor is delivered power divided by design power at certain period time. That really confused me.

That would confuse anybody. It is what I would call a “conversational English,” or shorthand, explanation. A college text book I keep at my desk defines “Load Factor” as follows:

Load Factor: The ratio of the average load over a designated period of time to the peak load occurring in that period.

Here are some examples:

A facility runs at 100% power all the time. Over a 24 hour period, the average power is 100%, and the peak power is 100%. The load factor is 100/100, a ratio of 1.0, or 100%.

A facility runs at 75% power all the time. Over a 24 hour period, the average power is 75%, and the peak power is 75%. The load factor is 75/75, a ratio of 1.0, or 100%.

A facility runs at 100% power for 12 hours a day, then shuts down completely until the next day. Over a 24 hour period, the average power is 50%, and the peak power is 100%. The load factor is 50/100, a ratio of 0.5, or 50%.

A facility runs at 75% power for 12 hours a day, then shuts down to a minimal 25% power until the next day. Over a 24 hour period, the average power is 50%, and the peak power is 75%. The load factor is 50/75, a ratio of 0.67, or 67%.

What is real demand in KVA? Do I have to use peak demand 1373KW divided by the load factor 71.07% to get peak demand in KVA?

You cannot use the load factor in any helpful way. You cannot “calculate” KVA, without knowing the power factor. But if your intent is to use this method to determine the existing load, and from that determine if there is room to add more load, then there is hope. You can assume a conservative value of power factor, like 80%. If from that assumption your calculation shows that there is plenty of room to add more load, then you have a reasonable justification. But if your calculation says there is no room, your choices become severely limited.