TRIP COIL

[tszpun]

Hello,

In the Medium voltage switchgear circuit breaker, i have 2 trip coils (shunt trip coil and undervoltage trip coil). Can I wire, 4 trip signals to them ? Or do i need a master trip relay?

 

[davidbeach]

Get rid of that undervoltage coil and replace it with a real trip coil. Then then 'A' relays on the 'A' battery trip the 'A' trip coil and the 'B' relays on the 'B' battery trip the 'B' trip coil. Then you have to decide whether the close coil goes on 'A' or 'B'.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[FreddyNurk]

Get rid of that undervoltage coil and replace it with a real trip coil. Then then 'A' relays on the 'A' battery trip the 'A' trip coil and the 'B' relays on the 'B' battery trip the 'B' trip coil. Then you have to decide whether the close coil goes on 'A' or 'B'.

Apart from hold-in burden, what's the penalty for using a UV release at MV (assuming it's available)?
Admittedly I've only ever seen UV releases used at LV and everything else uses trip coils, but had assumed that it was primarily due to the power requirement to keep the coil energised.

EDMS Australia

 

[che12345]

Dear Mr. tszpun (Industrial)(OP)7 Sep 22 03:30
"....$#1. in the Medium voltage switchgear circuit breaker, i have 2 trip coils (shunt trip coil and undervoltage trip coil). #2. Can I wire, 4 trip signals to them ? Or do i need a master trip relay? "
#1. In the LV i.e <kV CB, it is usual to have the possibility to install either UV or shunt release (i.e. only one NOT two). This is NOT usual with MV >1kV CB.
#1.1 FYI: An UV release has different operation characteristic/purpose from that of a Shunt.
#2. An UV or Shunt release can accept any number of trip signal. A master trip relay is required.
#2.1 FYI: (a) An UV release is usually wired with N.C. contacts in series. CB opens when any of the N.C. contacts opens or when voltage drops to <0.35Ur of the coil rated voltage.
(b) A shunt release is usually wired with N.O. contacts in parallel . CB opens when any of the N.O. closes when voltage is within 0.85 to 1.15 Ur of the coil rated voltage.
#3. Whether to use UV or shunt is dependent on your requirement.
Che Kuan Yau (Singapore)

 

[che12345]

Dear Mr. Dear Mr. tszpun (Industrial)(OP)7 Sep 22 03:30
Corrigendum
"....#2. An UV or Shunt release can accept any number of trip signal. A master trip relay is required."
should read A master trip relay is NOT required.
Che Kuan Yau (Singapore)