How does the positive-sequence voltage relay measure?
How does the positive-sequence voltage relay measure?
(OP)
Hello,
this is my first time posting in this great forum and I think I might have an interesting question.
I am performing some EMT simulations in order to study the effects of energizing a transformer. I have several transformers running in an islanded network and I get the sympathetic inrush phenomenon. Due to that the inrush magnetization current lasts longer and so does the voltage dip at a certain terminal.
At that terminal a positive-sequence voltage relay is installed and should issue a tripping signal 50 msec after the voltage goes below 0.84 p.u. It does go below 0.84 pu if I take the average. But due to the harmonics caused by inrush magnetization current this positive-sequence voltage is really jagged. It may jump from 0.7 pu to 1 pu several times during one cycle.
So my question is: does the relay filter the average value out of this jagged signal and will issue a trip or will it just follow the jagged signal and get resetted every time the voltage crosses 0.84 pu?
Thank you in advance.
Regards,
stason
this is my first time posting in this great forum and I think I might have an interesting question.
I am performing some EMT simulations in order to study the effects of energizing a transformer. I have several transformers running in an islanded network and I get the sympathetic inrush phenomenon. Due to that the inrush magnetization current lasts longer and so does the voltage dip at a certain terminal.
At that terminal a positive-sequence voltage relay is installed and should issue a tripping signal 50 msec after the voltage goes below 0.84 p.u. It does go below 0.84 pu if I take the average. But due to the harmonics caused by inrush magnetization current this positive-sequence voltage is really jagged. It may jump from 0.7 pu to 1 pu several times during one cycle.
So my question is: does the relay filter the average value out of this jagged signal and will issue a trip or will it just follow the jagged signal and get resetted every time the voltage crosses 0.84 pu?
Thank you in advance.
Regards,
stason






RE: How does the positive-sequence voltage relay measure?
Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.
RE: How does the positive-sequence voltage relay measure?
Thanks!
RE: How does the positive-sequence voltage relay measure?
RE: How does the positive-sequence voltage relay measure?
RE: How does the positive-sequence voltage relay measure?
RE: How does the positive-sequence voltage relay measure?
Regards
RE: How does the positive-sequence voltage relay measure?
On this moment, please see attached
Good Luck
Slava
RE: How does the positive-sequence voltage relay measure?
According to the manual the time delay can be set to 0 ms to issue a tripping signal after the measurement unit has picked up. Which means the relay does not average and will be resetted every time the measured value exceeds the reference value. Which in my case with jagged values would mean no tripping.
What could possibly inhibit the resetting of the relay is the reset time and the hysteresis (Email from ABB).
Thank you everybody once again.
Regards
RE: How does the positive-sequence voltage relay measure?
RE: How does the positive-sequence voltage relay measure?
the positive-sequence voltage serves as a reference value, not the momentary values of phase voltages.
Regards