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Can someone help me out with Generator Power factors and consequences when working on a network or island mode?
I got asked today what would happen when the power factor of a generator got more lagging. I said that would depend on what caused it to get 'more lagging'.... Surely this could mean that the KW has dropped and the KVar has stayed the same, or the Kvar has increased and the KW has stayed the same, this could be due to a number or things. Guy says that KW are always going to be the same on a generator in island mode and that only KVar would change to make the powerfactor go 'more lagging' ... The impact this would have is that the generator would get reverse Vars from the loads and trip on reverse power.
I just thought this is wrong? Reverse power trip on generators is only when the system receives amps from loads or networks isn't it? Say if I lost the engine to my generator, the loads or network would supply amps to the Generator because it is now motoring. This would cause a reverse power trip. Maybe I'm completely wrong..
I thought if the power factor went from 0.8 lag to 0.5 lag, the problem could be either the prime mover is unable to keep up with the current demand and the generator would trip on overload or under frequency (because it would be drastically trying to power the load), or say the current demand is fine, but the Vars are greater. The AVR has to supply a great deal of excitation to the generator to keep that load running? This could cause problems in the currents induced in the generator and could cause a trip on overheating of the exciter or rotor? If someone could explain what would happen when going from 0.8lag to 0.5lag that would be much appreciated.
I have the same question when connected with another generator in a network and the PF of one machine falls to 0.5, what would happen and what would you do. But I'd rather have a sound knowledge of what would happen in the first case before I move on.
Thanks
I got asked today what would happen when the power factor of a generator got more lagging. I said that would depend on what caused it to get 'more lagging'.... Surely this could mean that the KW has dropped and the KVar has stayed the same, or the Kvar has increased and the KW has stayed the same, this could be due to a number or things. Guy says that KW are always going to be the same on a generator in island mode and that only KVar would change to make the powerfactor go 'more lagging' ... The impact this would have is that the generator would get reverse Vars from the loads and trip on reverse power.
I just thought this is wrong? Reverse power trip on generators is only when the system receives amps from loads or networks isn't it? Say if I lost the engine to my generator, the loads or network would supply amps to the Generator because it is now motoring. This would cause a reverse power trip. Maybe I'm completely wrong..
I thought if the power factor went from 0.8 lag to 0.5 lag, the problem could be either the prime mover is unable to keep up with the current demand and the generator would trip on overload or under frequency (because it would be drastically trying to power the load), or say the current demand is fine, but the Vars are greater. The AVR has to supply a great deal of excitation to the generator to keep that load running? This could cause problems in the currents induced in the generator and could cause a trip on overheating of the exciter or rotor? If someone could explain what would happen when going from 0.8lag to 0.5lag that would be much appreciated.
I have the same question when connected with another generator in a network and the PF of one machine falls to 0.5, what would happen and what would you do. But I'd rather have a sound knowledge of what would happen in the first case before I move on.
Thanks