Smart questions
Smart answers
Smart people
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login




Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Donate Today!

Do you enjoy these
technical forums?
Donate Today! Click Here

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Jobs from Indeed

Link To This Forum!

Partner Button
Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

majesus (Electrical)
6 Oct 08 18:01
In Circuit Breaker applications, what is the difference between a Shunt Trip and a Trip Coil?

For instance in one 600V PDC drawing, I see that the relay which trips the 2000A secondary CB is labeled as "ST."

However, for the 4kV PDC drawing, I see that the relay coil that trips the 2000A secondary CB is labeled as "TC."

The intended purpose of both types is to trip the CB (that's easy! j/k)... But I'm curious, what is the difference between the two types?  

Regards,
Maj
alehman (Electrical)
6 Oct 08 20:56
To my knowledge they are one and the same. Usually "shunt trip" is a term used in low voltage, e.g. molded case, circuit breakers where it is commonly and add-on component. For power breakers, it is a standard component and is more commonly called a "trip coil".
bfuchs (Electrical)
6 Oct 08 21:07
A "trip coil" can be either :
- shunt trip coils : were the application of voltage causes the coil to trip the breaker
- an undervoltage trip coil : where removing the voltage causes the coil to trip the circuit breaker (or application of voltage of voltage is required to close and maintain the breaker closed)
waross (Electrical)
6 Oct 08 21:44
A shunt trip is a voltage coil. Some trip coils may be current dependent.

Bill
--------------------
"Why not the best?"
Jimmy Carter

majesus (Electrical)
8 Oct 08 2:43
Thank you guys... You know, I called the engineer who drew these drawings and asked him, because I am ALWAYS curious about these things and it will bug me until I learn why...

Like Aleham said, "shunt trip" is the term used in low voltage, e.g. molded case, circuit breakers where it is commonly an add-on component. The CB has thermal/magnetic trip capabilities, but it also has the ability to trip electronically say from a Feeder Protection Relay say like the GE SR750.

"Trip Coil" was used in reference to Power CB (in this case Medium CB.) The CB has no thermal/magnetic trip capabilities, it requires "brains" to tell it when to trip electronically from a monitoring relay such as the GE SR750 :)

Cheers,
Maj




 

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close