Let's say we have 3 phases A, B and C
Normal operation phase voltages:
VAB=V
VAC=V
VBC=V
A phase grounded:
VAB=V/sqrt3
VAC=V/sqrt3
VBC=V
Correct me if i'm wrong.
It's not homework:)
In case of fault one phase voltage remains unchanged and other two phase voltage becomes equal to line voltages.
What I don't get it why no change in secondary if primary voltages have chaneged?
Hello,
Let's say we have transformer. Primary(delta or star) is connected to medium voltage, neutral is isolated. Secondary(star) connected to low voltage, neutral is solidly grounded.
What primary and secondary phasor diagrams would look like in case of 1 phase ground fault in medium voltage...
So my only option is try to make ramp down time as long as possible and turn torque control during stop ramp on?
Currently I have 10 s ramp down time. Torque control is on.
Can you point me to some papers/literature about dc component and when/why it is a problem.
We have a problem with several pumps.
Pump motor P = 90kW, In=166A, 400V connected through 250A adjustable circuit breaker and ABB PSE170 soft starter.
The problem is that when motor is switched off either circuit breaker or soft starter trips quite frequently.
I suspect that at switch off motor...
Do I understand this correctly?
In case of a earth fault capacitive currents of healthy feeders connected to same busbars will flow through faulty feeders circuit breaker.
If there is no any cable lines connected to same busbars there will not be any additional current in case of a fault.
Wind turbine connected to distribution network.
Earth fault in this case shouldn't trip at all it only signals that there is earth fault and proper action should be taken before second earth fault.
I do understand that current will be very small, but i think relay will be able to sense it.
I have a question regarding directional earth fault settings calculation in ungrounded system.
Typical system i'm concerned is a small source(wind turbine) connected to MV system through LV(0.4kV or 0.69kV)/MV (10kV or 20kV) voltage transformer. LV side is solidly grounded, MV side is...
