ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
(OP)
I am attempting a load flow analysis on the following setup:
I have an oversized generator (550kVA) coupled with a gas-fired turbo engine whose output is 400kW at pf=1. Since the output of the generator is limited by the output of the engine, how is this represented in ETAP.
Specifically, when I add the properties to a generator in ETAP, on the RATING tab there is a Rating field (for the generator) and a Prime Mover Rating. If I fill in both rating fields, the Prime Mover Rating does not seem to limit the generator output when I do a load flow analysis.
Would a guy simply "derate" the generator capability to that of the engine output? Additionally, generators have efficiency relations based on loading so how would this be reflected if I simply derated the generator.
Im kind of lost here as to the proper way to make this happen.
I have an oversized generator (550kVA) coupled with a gas-fired turbo engine whose output is 400kW at pf=1. Since the output of the generator is limited by the output of the engine, how is this represented in ETAP.
Specifically, when I add the properties to a generator in ETAP, on the RATING tab there is a Rating field (for the generator) and a Prime Mover Rating. If I fill in both rating fields, the Prime Mover Rating does not seem to limit the generator output when I do a load flow analysis.
Would a guy simply "derate" the generator capability to that of the engine output? Additionally, generators have efficiency relations based on loading so how would this be reflected if I simply derated the generator.
Im kind of lost here as to the proper way to make this happen.





RE: ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
RE: ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
If the load KVA exceeds the generator KVA the generator will overheat.
The generator PF is 0.7273 (400kW/550KVA)
The PF of the prime mover is ????? I don't know what the PF of a prime mover is unless it is an electric motor.
Bill
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"Why not the best?"
Jimmy Carter
RE: ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
RE: ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
A prime rated set may be operated at a 10% overload for 1 hour out of 12 hours.
This implies that it may be safely operated at full load and a PF of 0.7273 for 1 hour out of 12.
I suspect that your set is prime rated and the prime mover is capable of supplying 440 kW for 1 hour out of 12.
However that information is not given and you must verify it yourself before you assume that the set is prime rated.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
waross- Disregard that point about the engine PF- I blindly rewrote exactly the specs that the sales guy gave me, obviously its a conversion from mechanical output to 400kWe.
Back to my question- seems like dpc and I are on the same page. Using the voltage control setting is ETAP's way of setting the output of the generator despite prime mover power.
What I have yet to understand about ETAP is what's the point of even inputting the prime mover rating as it doesnt seem to affect the generator output.
As well, where or how are the efficiency curves are instituted. The prime mover may be 400kW, but based on pf you lose a few % power, not necessarily represented by settings in ETAP.
Anyway, thanks everyone for your input! Helpful as always!
RE: ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: ETAP Generator and Prime Mover Rating Clarification w/ load flow analysis