How to trigger CBFP of REF541 from external source?

[martinergb]

I have a problem when configuring ABB REF541. I want to use CBFP of REF541 and I want to use a digital input to externally trigger it. But CBFP signals of REF541 can only be generated from individual protect function (e.g. NOC3, NEF1...), delay time is set in each function block and external triggering of CBFP is not available. It is not like REF610, REF610 has a separate CBFP and it can be externally triggered by using a digital input. Can anybody tell me how to build that kind of CBFP for REF541?

 

[slavag]

Hi.
No problem.
Please explain exactly what kind of CBFP you would like.
Whait is propose of this trigger. For example, you can use this trigger fot changing group of settings, you can deblock some function ( not used) like to NOC3Low. You can use CB status and function like to MECUA-3 for currnet detector and some internal timer, etc...

Best Regards.
Slava

 

[martinergb]

Thanks for your answer. CBFP I want to have is exactly the same as CBFP of REF610. To give you more information, I have taken some sentences from REF610 "Technical Reference Manual" about its CBFP: "The CBFP can also be selected to be triggered externally by applying a digital input signal to the relay. In this case, the CBFP generates a trip signal via an output if the current has not been cut off on expiration of the set operate time. External triggering is inhibited when all currents fall below 12 percent of the rated current In. External triggering is selected by activating CBFP in switchgroup SGB".

I use two relays, REL670 for main protection, REF541 for backup protection. Trip signal from REL670 is connected to a digital input of REF541 to trigger CBFP of REF541. When a fault occurs, trip signal from REL670 is sent to REF541, after a settable delay time and the current has not been cut off, REF541 will issue a CBFP signal via a digital output.

When I use CAP505 to configure REF541, I try to find a function block with the name CBFP (or 50BF...) to meet my need but there is not any. The only thing I found is the CBFP outputs from protect function blocks.

 

[slavag]

OK. As I saied before, no problem.

REL670 are include special function 50BF or RBRF.

REF54_ aren't include a dedicated 50BF function, like to REL670 or simple 50BF, like to REF610.
But you can build it in the CAP505.
Gate AND, one pole to this digital input , seconde pole to high limit alarm ( have setting in control panel of this functio) of MECU3A module, output of AND gate to timer TON ( you can connect via SWGR for setting timer) and after timer connect to contacts.
Or inverse signal CBFP init. from REL connect to BS1 of not used NOC and set NOC as needed. Simple and more flexible, you can add to this logic also contacts 52a/b.

Good Luck.
Slava

 

[martinergb]

High limit alarm of MECU3A can be set at the minimum value of 80%xIn. I think it is rather large and the first solution is not applicable for me.

The second solution is very good but I still have a question. This is what I read from NOC3 manual: the DT or IDMT timer of NOC3 is allowed to run only if the blocking signal BS1 is inactive, i.e. its value is FALSE. When the signal become active, i.e. its value turns to TRUE, the timer will be stopped (frozen). I do not understand the meaning of "will be stopped". In my opinion, "will be stopped" means that if the timer has already started and then BS1 turns to TRUE, the timer will stop but the value inside the timer does not reset to 0. When BS1 turns to FALSE, the timer will continue counting from that value. It will cause problem because the actual delay time is not the setting delay time when BS1 turns to TRUE and FALSE many times.

 

[martinergb]

By the way, I have a stupid question, What are contacts 52a/b?

 

[ScottyUK]

52 is the ANSI code for a circuit breaker. The 'a' contact mimics the breaker contact position, and the 'b' contact is the inverse of the breaker contact position.

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If we learn from our mistakes I'm getting a great education!

 

[slavag]

Hi.
52a/b are means circuit breaker status, aux. contacts of CB ( 52-ANSI code of CB).

OK, good Q's.

About first solution , you can use NOT LOW LIMIT in your logic. setting from zero to 80%.

Yep, BS1 it's some frozen logic. Timer not reseted to zero.
When TRUE of block changed to FALSE, timer run from stop point to time setting ( possible say "unused" time). But of course you need start situation of protection.

BS2 used for the block of trip signal only, timer aren't frozen .

You can use BS1, becouse you always in block situation up to signal from your main protection.

 

[martinergb]

Is it OK if I use NOC3Inst, set Operation Mode to Instantaneous (START and TRIP operate at the same time), CBFP output of NOC3Inst is connected to an digital output?

 

[slavag]

Yep.
Good solution!

Best Regards
Slava

PS. Why you need CBFP from REL670 via REF54_? Are it sub transnission line, something like to 138-150kV?

 

[slavag]

Sorry. From other hand.
You have think also about signalization.
In this case, I think you need use more complex logic.
set DT, not Inst., for the about 80ms, for trip to the same CB and CBFP to upstream CB. You need some time for the open CB and reduce faulty current.
Best Regards.
Slava

 

[martinergb]

Thank you very much, I think that is the best solution for me. I use these relays for 110kV overhead line.
I have another question: I use a PT with the ratio of 110kV/?3:100V/?3 and then connect it to channel 10 of REF541, signal type is set to U1. The rated voltage of the secondary side of the PT is 63.5V but in CAP505, I can only find 4 numbers to chose: 100V, 110V, 115V, 120V. What can I do now?

 

[slavag]

Hi.
Good Morning.

100/110/115/1120V for a phase to phase voltages.
You need set 100V as scale and it translate 63.5V phase to neutral voltages to 110kV primary accordantly.

BTW, you can use additional channles for meas. or protection: U12s, U23s and U31s, it's internal calculated phase to phase voltages.

Best Regards.
Slava