Finding KVA or KW of Generator

the manufacturer.

Dear frd ,

Take one Clamp meter and start the DG set and check each phase Amp's by that you can calculate KVA / KW.

Thanks

Try to identify the size of the phase conductors. Use the formula for 3 phase and work backwards. That should get you close. (Of course, you could contact the name of the manufacturer). The phase conductors would be on the supply side of the Breaker if the generator has a breaker. Otherwise, just size the conductors attached to the output terminals. Good Luck.

Give me the impedance of the rotor and the voltage the slip rings use and current at the slip rings with a load on any of the phases, say 1000W. make sure the load is resistive like a bulb, no inductive load for this test. With these numbers there is a logarithmic curve for magnetic saturation proportionate to the impedance and load on the rotor from the excitation needed to deliver the final output.As generator fields get bigger, so does the magnetic field of the rotor. I would say read the exciter name plate, but those are always over rated for what they do.

J.R. Watts, Professional Engineer

you just need to know your operating voltage and full load current....and as for power factor, pf of 0.8 is acceptable for mostly generators are designed at this standards..in our industry we have three turbo-gen(steam propelled) all are at o.8 pf...or try using a kWHr meter..this will give you a rough estimate of your units capacity...

First get the operation manual of the generator. I presume that this document is also not available therefore this question has been asked. There are number of gausses that you can make to arrive at approximate rating of the set:

1. Look for the prime mover rating and then converting the same to KW or MW.
2. Look for measuring CT and PT primary side rating. Then product of voltage, current and under root 3 will give approximate VA rating
3. If the set is connected to step up transformer then rating of the transformer can also give approximate rating of the set.
4. See the name plate rating of the load connected (at least you will get the idea of the rated voltage of the generator.

If above steps can give some idea of the rating then you can further refine the information by following steps.

1. Look for the temperature detectors or thermometers for measurement of temperature of core and winding
2. Measure the resistance of rotor winding resistance when cold ( it mat take quite some time to attain room temperature for the rotor winding.) and correct it for 20 degree centigrade.
3. Perform Open Circuit Heat run (running the generator with open circuited stator terminals ) till temperature RISE above cold inlet coolant temperature of all active parts become constant (less than 1degree per hour).
4. Short the terminals of the stator winding and excite the stator winding so that circulating current is say 80 percent of approximate current rating obtained from steps 1 to 4 above. Observe the temperature rise of stator winding and see how much it is near the permissible limits (This limit would be based on the class of insulation that is class B ,F etc)
5. The full load temperature rise can be calculated as the sum of temperature rise under Open Circuit Heat run and The same under Short Circuit Heat run. Find out the full load temperature rise for all the active parts. In case full load temperature rise is less than permissible rise then you may take another Short Circuit heat run with increased stator winding current. If needed 2-3 such runs can be taken (and extrapolated then if necessary) to arrive at desired full load temperature ( depends how much margin you want to have for different approximations, age of the machine cooling conditions etc.
6. Generator rating would be under root 3 times stator voltage and the current (as obtained by above heat runs).