CT polarity for High impedance differential protection motor
CT polarity for High impedance differential protection motor
(OP)
Hi Guys,
Can any body give CT Polarity for a High impedance differential protection for HT Motors.CT polarity in the Line side of a motor and in the neutral side of a motor.
Can any body give CT Polarity for a High impedance differential protection for HT Motors.CT polarity in the Line side of a motor and in the neutral side of a motor.






RE: CT polarity for High impedance differential protection motor
JIM
RE: CT polarity for High impedance differential protection motor
In my schematic they have not shown the neutral side CT's
in line side P2 is towards motor winding,What will be the polarity of neutral side of the motor
RE: CT polarity for High impedance differential protection motor
RE: CT polarity for High impedance differential protection motor
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If we learn from our mistakes I'm getting a great education!
RE: CT polarity for High impedance differential protection motor
Here with i have attached the sketch diagram of my circuit can u give me the current flow during the healthy condition and also during the fault condition.relay used is spae010
RE: CT polarity for High impedance differential protection motor
RE: CT polarity for High impedance differential protection motor
What Tsknan saied.
Your connection is correct.
But you need relay documentation for right calculation of varistor and resistor and right secondary wiring dimention.
Best Regards.
Slava
RE: CT polarity for High impedance differential protection motor
It is very easy to apply and it doesn't matter which way P1 and P2 are facing.
RE: CT polarity for High impedance differential protection motor
With the above attached documentwhat is your opinion whether diff current flows in to the relay during healthy conditions of motor.
RE: CT polarity for High impedance differential protection motor
Isn't important what is a connection.
Rules: P1 "in" current-S1 "out"current
P2 "in" current-S2 "out" current. Isn't important if it's star point of CT's.
You are protect a motor. Current is only "in" from line/bus
(OK, we don't take in account contribution of motor in case of external SC). In case of SC into a motor, current "in" from the line/bus, flow via line CT, but don't continiue flow via neutral CT (or partly only). This disbalance or diffirential current flow via varistor/resistor and make voltage on the protective relay terminals. Relay will trip.
Hope that help you.
Good Luck.
Slava
RE: CT polarity for High impedance differential protection motor
If current flows in P1, it flows out S1
RE: CT polarity for High impedance differential protection motor
i have the connection as per attacment and i also do the stability test and the result also found ok.i have done stability by applying 415 V supply to the motor for a short duration and stability is also found ok.the motor rated voltage is 6600V.Applying 415 v supply doing stability is right procedure,Any limitation in this procedure or any body can give any other method of doing stability test for motor