Close and Trip Relay

[alivip]

As you know, in Protection system we usually use close and Trip relay between Main relay (as commander) and circuit breaker.
These relays must have to main features, Heavy duty and high speed.
The main use of these relays is that, when main relays (for example Distance relay) sends trip to CB, about 4ampere are used by inductor of CB.
hen the relay contact wants to break this current ,it must withstand Ldi\dt voltage . this voltage usually results to destroy main relay contact.
So, based on this philosophy which above mentioned, we use trip and close relay.

After improvement in CB mechanism, the CB contact position is used in the path of relay and CB coil. So the trip current is broken by this contact (for example after CB is tripped, the CB will be opened, so the CB contact will be opened and breaks the trip current)

But we still use trip relay and close relay between main relay and CB,,why?
---------
For example we use 7PA27 Siemens relay as Trip relay and 7PA23 Siemens relay as Close relay.

I know just one reason.

 

[odlanor]

jghrist

Why not use latched trip with reclosing?
answer:
85% of the arc faults on overhead lines are extinguished automatically after being tripped by the protection.
In a succesfully reclosing, protection will reset and reclose command can be effective.
If use latched trip, close command will abort before a effective closing operation.

 

[davidbeach]

What is so difficult about latching the trip until the breaker opens? Then it unlatches. In plenty of time for the reclose. This isn't rocket science, just basic protection engineering.

 

[slavag]

Good Morning.

I would like remaind, Im not use interposing relays.

Maybe we have some misunderstanding.
But normal practic for protection and for CBFP (BFP, 50BF) not used 52a contact,only current ( ok not for all cases, low current situation is something other).

In system with autoreclosere alwayas used 52a contact, but only in terminal with this functionality, that menas in main 1 terminal, trip, not trrip contact is latched up to end of abnoraml situation.

Please take in account a problem case, not CBFP situation, breaker is openeed, but 52a contact in series with trip coil was not opened, only one contact.

 

[odlanor]

alivip,
I think your explanation is not applicable to single shot reclosing.
slavag,
It is not so simple. I always use interposing relays. It is a cultural issue. To delete it I need to be persuasive.

 

[slavag]

Hi.
Yes, its something historical.

Someone need decide, with or without.
From technical point of view, iterposing relays are not needed, imho

 

[davidbeach]

Perhaps it is cultural, but I've seen nothing that suggests any benefit to interposing relays and lots of disadvantages. Those interposing relays seem to be a solution in search of a problem. Our protection practices, without any such interposing relays, accomplish everything that the interposing relays supposedly make possible. If all the "benefits" of the interposing relay can be achieved without the interposing relay then good engineering practice is to eliminate the interposing relay and reduce the possible failure points.

 

[alivip]

i hope some one who has connecting with Siemens ask from them why they produce trip and close relay.

 

[slavag]

Siemens it something very big .
I have noe some projet with Siemens w/o any inerposing relays.

 

[alivip]

anyhow Siemens produces 7pa23 and 7pa27 relays for many years and surly they have philosophy for their uses.

 

[slavag]

btw.
Close relay is other issue, from time to time we use it for duplicate contacts, for Manual Close indication (SOTF, distance protection and for end-fault protection or BBP protection of coupler)

 

[alivip]

Anybody can help us about SEL set relays for this purpose Vs Siemens?

Based on my information :

Close relay : Siemens (7PA27) SEL (?)
Trip relay : Siemens (7PA27) SEL (?)
TCS relay : Siemens (7PA30) SEL (SEL 2652)
lockout relay: Siemens (7PA23) SEL (?)


I also found SEL-9502 Contact Arc Suppressor , is that use for the same purpose as trip or close relay?


Regards,
Alireza

 

[dpc]

AFAIK, SEL does not make a utility-grade interposing relay or lockout relays.

For lockout relays, US suppliers would be Electroswitch, GE, and Shallco among others.

The SEL surge suppressors are not relays, they are connected in parallel with the relay output contact and reduce the surge voltage that the output contacts have to withstand.



David Castor

http://www.cvoes.com

 

[davidbeach]

SEL does not make trip, close, or lockout relays. The SEL-2652 does exist, but we can do the same thing by connecting an input to the trip or close bus and don't bother with a separate device. Lockout relays would typically come from somebody like Electroswitch. The Contact Arc Suppressor (SEL-9501 or SEL-9502) will absorb the voltage, and therefore reduce/eliminate the arcing, that could be caused if the relay output contact tries to interrupt trip or close coil current.

They also have optional hybrid contacts on many relays. In the hybrid output, there is a solid state relay that is used for making and breaking while a mechanical contact does the sustained current carrying.

 

[alivip]

thanks,

but i hope i could find the same suitable replace for Siemens interposing relays,do you have any suggestion from number one brands?

i don't know electroswitch co. As i know the only number one brands for relay are : ABB. Siemens, SEL AREVA GE

i think , it is right that SEL-2652 is not trip or close relay, but it is good replacement for trip relay. i mean we can use this relay instead of 7PA27 relay

 

[dpc]

GE makes lockout relays - GE HEA

And GE makes utility-grade aux relays: See GE HAA, HFA, and HGA.

These have been in production for 50 years at least.

An interposing relay in a trip circuit is not a place to start comparison shopping. Buy something with a proven history and don't get too concerned about saving money.





David Castor

http://www.cvoes.com

 

[slavag]

ABB for many years make Combiflex series relays.
RXMB, RXMS ( very fast tripping relays), RXMD (bistable relays, like to LOR, but electrical reset).
But need some expirience with wiring and ordereing of such relays.

In the same series TCS relays--SPER1B1, SPER1C4.

In the last project, I was used not bad interposing Spanish relay ARTECHE RF-4R, also nor so expansive.

Actually for simple trip relay is possible use a good range of power realys, like to Finger.

Trip coil supervision, possible use a nice Germany product
TSG910, TSG930

 

[alivip]

SPANISH ARTECHE RELAYs have good price , BUT IT IS NOT accepted by consultants,

GE and ABB are a good choice but their package for trip tcs lockout are more expensive than Siemens relays,

i hope i could find them in SEL products..but i cant find anything.

 

[odlanor]

I am using ,just now, Spanish relay ARTECHE RF-202XR and RF-4XR - T<5,5ms.

 

[alivip]

is it SEL-9502 Contact Arc Suppressor good replacement for close and trip relay (7PA27) ?

 

[davidbeach]

They aren't even the same thing.