Transmission line reclosing

[mbrooke]

What are the recommended reclose settings on two and three terminal 69 and 115kv lines protected by relays (311C) without any communication between them? Do you set reclose on both or simply have one do the re-closing? If only one does reclosing, how do you get the other relay to close if the fault is transient since it will be locked out?

 

[Phil Corso]

Mbrooke...

Are you looking for"Reclosing Strategy", or actual timing values?

Phil Corso

 

[mbrooke]

Mbrooke...

Are you looking for"Reclosing Strategy", or actual timing values?

Phil Corso

I am looking for a re-closing strategy. I have already decided on a 30 second re-close after the first trip.

 

[peter d]

8.9 giggaseconds.

 

[mbrooke]

8.9 giggaseconds.

Its not the timing a I am worried about, rather getting a single reclose attempt to work with no communications between the relays. Normally both relays would make a single reclose attempt preventing either on from progressing to lockout if the line is still healthy.

 

[Phil Corso]

Its not the timing a I am worried about, rather getting a single reclose attempt to work with no communications between the relays. Normally both relays would make a single reclose attempt preventing either on from progressing to lockout if the line is still healthy.

Mbrooke...

The "communication link" is the fact that they should "see" the same fault!

Phil

 

[mbrooke]

Mbrooke...

The "communication link" is the fact that they should "see" the same fault!

Phil

True, but one has to respond differently than the other.

 

[NewtonLaw]

What are the recommended reclose settings on two and three terminal 69 and 115kv lines protected by relays (311C) without any communication between them? Do you set reclose on both or simply have one do the re-closing? If only one does reclosing, how do you get the other relay to close if the fault is transient since it will be locked out?

To ensure you get the best answer I would suggest you sign on to https://selinc.com/products/311C/ and ask their technical support for the proper settings. My experience has been to set only one circuit breaker of a multi-terminal transmission to have the right of way to reclose to test the line. I.E., set one CB's 79 function to close and test. This can be done without any communications to other terminals using the 331C (or other relays) simply by blocking auto reclose of all other terminals until the line is restored to power. Reclose timing may be set as you wish on the terminal with right of way but should be delayed long enough to allow complete deionizing of the line and fault path. Usually about 1 to 2 seconds maximum. Hope this helps.

 

[mbrooke]

To ensure you get the best answer I would suggest you sign on to https://selinc.com/products/311C/ and ask their technical support for the proper settings. My experience has been to set only one circuit breaker of a multi-terminal transmission to have the right of way to reclose to test the line. I.E., set one CB's 79 function to close and test. This can be done without any communications to other terminals using the 331C (or other relays) simply by blocking auto reclose of all other terminals until the line is restored to power.

Makes sense, but how do I stop the non-reclosing relay from going into lockout after the first trip?

Reclose timing may be set as you wish on the terminal with right of way but should be delayed long enough to allow complete deionizing of the line and fault path. Usually about 1 to 2 seconds maximum. Hope this helps.

20 to 30 seconds for me :thumbsup:

 

[GoldDigger]

Makes sense, but how do I stop the non-reclosing relay from going into lockout after the first trip?

I guess the question is whether the relay has logic that prevents it from reclosing from a live segment onto a dead segment but allows it to reclose when both sides are powered (and syncronized?).

 

[mbrooke]

I guess the question is whether the relay has logic that prevents it from reclosing from a live segment onto a dead segment but allows it to reclose when both sides are powered (and syncronized?).

Yup, thats the meat of my question. Albeit the my original post danced around it a bit :ashamed1:

 

[Bugman1400]

Did you ever get a clear answer on this? I believe Newton's answer is the most helpful. You can stagger the reclose times to achieve what you want. You can also use logic to change which terminal closes first depending if one terminal is out of service. This logic can be controlled via the front pushbuttons or a panel selector switch. You will also have to pick which end will close first and make the first "test" of the line after a fault. The other two terminals can reclose on sync after that.