Trip coils 1 and 2

[bejoyengineer]

What is the need of having two trip coils like Trip coil # 1 and Trip coil # 2? Is it to identify which fault has occured and by which relay? because i have noticed that in one single line diagram - O/C relay is connected to one of the Trip coil crkt and bus relay was connected to another TC-2. but if that was the reason - then we could see the status in either the SCADA or SOE or annanciator. So for what and why do we use the trip coils?

 

[zog]

Huh? I am having a hard time understanding your question, can you rephrase it and provide some detilas on the breaker type you are asking about? There are dozens of possible answers to your question, need more info.

 

[jghrist]

What is the need of having two trip coils like Trip coil # 1 and Trip coil # 2? Is it to identify which fault has occured and by which relay? because i have noticed that in one single line diagram - O/C relay is connected to one of the Trip coil crkt and bus relay was connected to another TC-2. but if that was the reason - then we could see the status in either the SCADA or SOE or annanciator. So for what and why do we use the trip coils?

Normally, two trip coils are used for reliability, to mitigate possible trip coil failure. Primary relaying trips one and backup relaying trips the other. Unless you have a limited number of output contacts on your relays, however, it would be more reliable to have each relay trip both trip coils. I really don't see the fault identification function. You can get this information from the relays. Without the information from the relays, how do you know which trip coil operated? They don't have auxiliary contacts.

 

[richxtlc]

Normally, two trip coils are used for reliability, to mitigate possible trip coil failure. Primary relaying trips one and backup relaying trips the other. Unless you have a limited number of output contacts on your relays, however, it would be more reliable to have each relay trip both trip coils. I really don't see the fault identification function. You can get this information from the relays. Without the information from the relays, how do you know which trip coil operated? They don't have auxiliary contacts.

You are correct with your evaluation of the two trip coils used for reliability, they are both energized when a trip occurs, by either the primary or the redundant protection, not the backup protection. The target information is obtained from either the flags or target indication on the initiating relays. The reason I use redundant protection instead of backup protection is that backup protection is designed to trip the next zone of protection, not the original faulted zone. if the backup protection operation additional equipment is de-energized.
Redundant protection uses seperate cts,pts, batteries, operates one of the Trip Coils usually TC#1. It trips the identical equipment that the primary protection trips, but does it with different LORs or protective relays. In many cases the protection package is identical in both the primary and redundant relay systems.

 

[jghrist]

...they are both energized when a trip occurs, by either the primary or the redundant protection, not the backup protection...Redundant protection uses seperate cts,pts, batteries, operates one of the Trip Coils usually TC#1. ..

You're right, redundant (or secondary) is better nomenclature than backup. Having the primary relay trip one trip coil and the redundant trip the other is the usual approach, but why not have each relay trip both trip coils if there are enough output contacts?

 

[richxtlc]

You're right, redundant (or secondary) is better nomenclature than backup. Having the primary relay trip one trip coil and the redundant trip the other is the usual approach, but why not have each relay trip both trip coils if there are enough output contacts?

In the utility industry, my experience is that each level of protection, primary and redundant will send a trip signal to each trip coil. This is to ensure that a trip will occur if one trip coil burn out during the event.