Close and Trip Relay
Close and Trip Relay
(OP)
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?
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For example we use 7PA27 Siemens relay as Trip relay and 7PA23 Siemens relay as Close relay.
I know just one reason.
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?
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For example we use 7PA27 Siemens relay as Trip relay and 7PA23 Siemens relay as Close relay.
I know just one reason.






RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay
But one of its benefit is that in the CBF times (when CB was tripped but it was not opened.) the CB contact is still closed , so Ldi\dt will be opened by relay contact. if we not use trip relay , maybe, it leads to impair main relay contacts in that time.
on the other hand,these interposing relay are still produced by manufacture ( Siemens,ABB AREVa...) and also are in Protection Schematic drawings.
(note : the main use of these relay is not for making current, it is for breaking time )
(note 2 : trip relay are not just between main relay and CB coil, it use between every thing should command open CB, for example discrepancy switch. close relay as the same is between A\R relay and .... )
(note 3 : trip relay and close relay price is about 400$ for each CB mechanism )
by considering all above items i think it must have a reason(s).
RE: Close and Trip Relay
RE: Close and Trip Relay
1. As you have righly put in your notes and your initial explaination above, the main reason for the trip relay in the present day protection system has been reduced to that of a "multiplication" relay that multiplies the trip contact (from distance relays etc)and used further on for various reasons.
2. Further, the main relay contacts that are used for tripping a breaker are high speed trip contacts. The close / Trip coil of a breaker is rated at 200 W (approx) while that of the close / trip relay's wattage rating is at Max 10 W.
In order to maintain the High Speed feature, the available ways are either by reducing the mass or by reducing the energy requirement. Since mass of these coils have more or less remained constant to achieve the closing or opening operation, the only way to maintain the speed high is by reducing the Energy requirements. Thus by routing the trip / close command via a relay, you are reducing the energy requirement of the main relay(which are predominantly numerical these days.)
Now suppose you want to route the command directly, this would increase the energy requirement of these Main relays which inturn would increase the Rated Burden of the CTs and PTS/CVTs which consequently increase in the size of these instrument transformers and hence the overall cost of the system.
I suppose the cost of the above change will definitely be greater than 400$ and hence a Trip / close relay.
RE: Close and Trip Relay
Numeric relays run off power supplies and place almost no burden on the instrument transformers. Your whole "2." doesn't make any sense.
RE: Close and Trip Relay
the main relays (numeric and others) have separate power supply (they usually supplied with DC system(battery or charger), So the load of CB coil dose not influence on them at all.
the brief conclusion : the only reason we can find till now is :
To prevent damaging contact relay just(and just) in breaking the trip current when we experience CBF faulty.
Anybody knows more reason?
RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay
the CBF (when trip comes and cb will not be opened) results : the cb contact between main relay and coil dose not change position so the role for breaking trip current will be done by main relay contact. ( just in this state we need trip relay)
the CBF function (86BF) does not make sense in this topic.
RE: Close and Trip Relay
RE: Close and Trip Relay
( fault will be clear by opening all CB connected to faulty CB ). so the CB will not be opened and the relay contact disconnect trip current.
RE: Close and Trip Relay
Some time ago I used another, much cheaper solution. Relay protection sends trip command to the CB directly. In the same time second contact of the relay protection, set also on "General trip", operates auxiliary relay of standard "contactor" type. Contact of this contactor duplicates trip command to CB trip coil. This way we still have high speed trip (without additional delay of external trip relay), but trip circuit is cut by powerful contact of the contactor, because relay protection's contact always drops-out first. Unfortunately I cannot implement this scheme in my current projects. I am sure it will not be approved - contactor type relay in 110 kV trip circuit doesn't look serious. It seems that my African client in that old project was more ready to accept some non-standard solution.
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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant
RE: Close and Trip Relay
your scheme is used in ABB protection scheme. AS you know ABB co. does not have trip relay and we use compounding tow set relay (one of them is high speed and for trip and other is heavy duty and used for breaking current). anyhow your scheme is cheaper.
RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay
I try hard to avoid using interposing relays on trip circuits but it worthwhile to note that the most common protective relay failure for the new microprocessor relays is output contact failure. Things happen.
These relays essentially already have an interposing relay built into the device in most cases, so adding another relay may decrease reliability instead of improving it.
David Castor
www.cvoes.com
RE: Close and Trip Relay
Im use interposiong relay only by special request of customer or in some special cases.
Marmite, btw, in the laqst project with Micom relays, for close I was used interposiong relays ( it was local Areva recommendation)
RE: Close and Trip Relay
I have seen some PLC outputs welded when used to trip just a lockout relay.
Also, if using interposing relays on a trip circuit, make sure they are extremely high quality. I have seen installation of some really wimpy interposing relays that were much less capable than the contacts they were supposedly protecting.
David Castor
www.cvoes.com
RE: Close and Trip Relay
and number of CB faults today...near to zero.
last project, I used a very cheaper trip relay= 90Euro, please add wiring and place into cubicle.
RE: Close and Trip Relay
1- the only use of Trip and close interposing relay is : To prevent damaging contact relay just(and just) in breaking the trip current when we experience CBF faulty.
2- number of CB faults today...near to zero.
3- Some consultant spec and clients still insist on using interposing relays
4- one of alternative relay : using power contactor parallel to main relay to coil (lz5pl scheme )
5- the price of using siemesn interposing relay for one CB (with 2 close coil )is about 600Euro.
i also don't understand about SEL Co. solution. is it possible to give me more detail information for this purpose.?
:)
RE: Close and Trip Relay
1- the only use of Trip and close interposing relay is : To prevent damaging contact relay just(and just) in breaking the trip current when we experience CBF faulty.
2- number of CB faults today...near to zero.
3- Some consultant spec and clients still insist on using interposing relays
4- one of alternative relay : using power contactor parallel to main relay to coil (lz5pl scheme )
5- the price of using Siemens interposing relay for one CB (with 2 close coil )is about 600Euro.
i also don't understand about SEL Co. solution. is it possible to give me more detail information for this purpose.?
:)
RE: Close and Trip Relay
Here is a link to the SEL device that dpc was referring to:
http://
RE: Close and Trip Relay
if anybody works with SEL products , i like to have a compare with Siemens scheme about our topic subject.
i upload a file containing single line diagram of O.H.L
AS you can see, it contains :
3 trip relay for coil one
3 trip relay for coil two
1 close relay for CB close coil
1 lockout relay
3 trip coil supervision(TCS) for coil 1
3 trip coil supervision(TCS) for coil 2
the price of the following relays will be about 1300Euro based on Siemens products.
is it possible give me the same scheme based on SEL products?
RE: Close and Trip Relay
David Castor
www.cvoes.com
RE: Close and Trip Relay
in my thinking, a CBF faulty in 500kV-CB with trip coils of 500W to 800W, the main relay 7PA27 contact will be damaged and TCS 7PA30 will verify that the Trip Coil are OK.
It will be necessary a visual inspection of the contact.
I guess this is not the purpose of the surge suppressor.
RE: Close and Trip Relay
anyhow as you said
TCS(7Pa30) use is : supervision of trip supply path of trip coil. it is used in closing CB interlock. if any fault exists in path of trip the TCS contact will be opened and the CB can not be closed (because in fault condition we can not open it).
Trip relay(PA27) : interpose between main relay and CB coil to break the trip current. it prevents damaging main relay contact.
RE: Close and Trip Relay
Possible use build-in 74 function into Siemens relay ( or other ), but you need additional binary input for every trip coil.
RE: Close and Trip Relay
excuse the mistake. In fact I never saw project with protection relay is used directly in the trip circuit. Always interposing relay is used. (94)
It is very popular to use the relevant set of fast relay RXMS1 ABB in parallel with AREVA-CS1C contactor.
I would like to know how to check if the trip relay(94) is suitable to prevent damaging contact relay during CBF faulty.
Assume a trip circuit for a 500kV CB with a trip coil of 2.5 ohm in serie with resistor of 20 ohm .
Trip relay(7PA27)data:
40A-0.5s-110VDC
1 contact non-inductive 125VDC- 1.2 A - 20 ms
1 contato inductive 125VDC 0.6 A - 20ms
Will be PA27 suitable?
RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay
yes, based on Siemens answer you can series contacts of 7pa27 to reach this capability ( i think 3 set is required)
davidbeach :
it will be unlatched because when cbf is started other cb (connected to faulty cb ) will be tripped and they cleared the fault so trip will be unlatched.
other note : there is not only main relay tripping to cb, consider that re closing relay and discrepancy (or push button) also command to open cb .
RE: Close and Trip Relay
ULTR = NOT 52a
Simple enough.
RE: Close and Trip Relay
Not in all cases to protective terminal is connected 52a signal.
Lot of versions.
And not always 52a contact is same position as main 52 contacts.
RE: Close and Trip Relay
Based on the reasoning of David,I present a general solution. Tripping will be made by 2 contacts in parallel:
1 - binary output for general trip of numerical protection relay.
2 - blocking relay(86BF) of breaker failure protection applied into CB defective.
With this we'll have the compound scheme of fast and heavy duty tripping.
slavag,
Why necessity of interposing relays at closing circuit?
RE: Close and Trip Relay
may be when auto re close send close command and the cb close coil can not close the cb, the circuit will be opened by close relay instead of main relay contacts.
RE: Close and Trip Relay
Seems like an extra 52a contact and an extra relay input would usually be cheaper than a tripping relay.
By definition, 52a contact is in same position as main 52 contact. I suppose that it is possible that the breaker will fail to trip, the 52a contact in series with the trip coil also fails to open, and the 52a contact energizing the relay 52A input does open. Anything is possible, but if it is very improbable, you can live with a very rare relay contact failure.
RE: Close and Trip Relay
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.
RE: Close and Trip Relay
RE: Close and Trip Relay
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.
RE: Close and Trip Relay
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.
RE: Close and Trip Relay
Yes, its something historical.
Someone need decide, with or without.
From technical point of view, iterposing relays are not needed, imho
RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay
I have noe some projet with Siemens w/o any inerposing relays.
RE: Close and Trip Relay
RE: Close and Trip Relay
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)
RE: Close and Trip Relay
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
RE: Close and Trip Relay
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
www.cvoes.com
RE: Close and Trip Relay
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.
RE: Close and Trip Relay
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
RE: Close and Trip Relay
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
www.cvoes.com
RE: Close and Trip Relay
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
RE: Close and Trip Relay
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.
RE: Close and Trip Relay
RE: Close and Trip Relay
RE: Close and Trip Relay