Recent content by wuqn

hi every body My underfrequency relay is used to remove load out of the generator (load shedding). I want to change the time delay. What delay is suitable ? How do i calculate the delay? the method ?

Dir sir/madam, My system's analog input card shows a fault led. After checked i found that the output voltage of an input was instable. Its flunctuates from 5-20 Vdc. The input is connected to a pressure transmitter. The system is TSX QUANTUM. The analog input card is 140 ACI 03000. What's the...

i found the problem. droop variable resistor's wire is broken

Thanks everybody. ScottyUK: the generatos are similar. rbulsara: the service is not good. Alex68: Can you show how to activate the AVR compound with a negative gain ? do I have to reduce the AVR's gain?

the system has three paralelled generators. But the power factor of the two is not stable. one's PF increase then the other decrease. I don't know why. what's the problem? how can i fix it? thanks.

the system has one generator. How much is reserve power so that I can start up a large motor? Ex: generator: 480kW, motor: 110kW.

thank everybody. But what's happen when the generator has very low excitation and is absorbing leading VAr's? Can you explain more?

we have 3 generators that are paralleled. Can we use capacitors to compensate the reactive power of the system? we want to reduce the current through the generators.

the generator is 550kVA.

the stator is wye. the center point is grounded. it's ok when i put load on it. but the voltage is still unbalance. the generator is paralled with other generators. may be the ground resistance is high ?

3 phases. run unload

hi when generator run, measured voltages : Vab= 417, Vbc=420, Vca= 392. Vca is much lower than the others. what's the problem ? how can i fix it? thanks

thank waross. the system has three paralleled generators. but one generator indicates :" negative sequence current is 2%". how can i do to fix it?

inspecting and maintenance electrical apparatus

droop, level and gain of AVR(automatic voltage regulator)'s is not set properly, can it cause negative sequence current ?