Multifunction relay 4

[slavag]

Hello.
What is your opinion about "new" generation of low impedance BBP is include bay protection.
We commissioned three such systems and I'm hope we contniue with it.
Isn't commercial thread. Please w/o types and companies.
I see the tread, as continues of two previous 521AB's threads.
Thanks for advance.
Regards.
Slava

 

[521AB]

I haven't done stations for some years, but something I have seen before. Change over, diodes, or something else usually at the end give troubles.
And as a good friend of mine (from utilities) told me last week: in the substation there are 2 important things: autorecloser and batteries.

A clean and simple dc design is the trick to make a good and reliable substation.

Relays with two power supplies? And what about the auxiliary relays like external trip units etc? And infos from primary equipments? How do you power those signals? And what about the out of order of one bay or part of it? Are you sure that all of this is under control?
I have been in substations where you switch off the DC-MCB for a cubicle, and still there is dc in the cubicle... :-(

 

[slavag]

OOO, those are very important points.
1. About autoreclosere, I'm not sure, btw, you don't provide any back-up for AR (78 function). Maybe only in case of 1 1/2 breaker , some duplex logic.
2. Yes double power supply, but really double, not some diode bridge into relay, diode bridge is veru dangerous and poor design ( in the floating systems "+ to grounding" in DC1 and "- to grounding" in DC2 = 440V DC at the devices.).
Only changeover relays, but per cubicle/feeder. I use it about four/five years, up today wasn't problem.
3. What is a biggest additional advantage of the numericak relays? not only protection and control, is option build some condition supervision of wiring and statuses in the substation.
3.1 IRF/ wathcdog of relays.
3.2 doble indication of each switching element
3.3 trip/close coil supervision
3.4 monitoring of CB/DS open/close running time.
3.5 relay's DC supply condition, for each relay in additional to central DC monitoring.
3.6 CT/VT wiring condition, it's high importance.
possible continue.
Our colleguas from Russia sended me new requeremnts to protection from 02.2008. New request: monitoring of trafo electromechanical protection ( Buchholtz) wiring. I think ins't bad idea.
Now about alarms: we used for alarms like to MVB aux contacts, IRF's, etc.. other( independent) voltage: 220V AC UPS, 60V /48DC from NCC, voltage from annunciators ( suplied by 220V AC from UAT and UPS)
Regards.
Slava

 

[commissionin]

Hello Dears..

Pls guide me how to test broken conductor test in Micom P142 relay. also explain the basic fundas 4 the said content. we are using freja & sverker as a testkit.

Hope your kind considerable earlier reply.......

 

[slavag]

Hi.
I'm not familiar with this type of relay.
But we'll try togehter solve this problem.
broken conductor usually base on :
dI= (Imax-Imin)/Imax or Iavr or something like to this.
Please check according to manual.
Connect three-phase current to relay, but w/o connection to I0 ( or disconnect this function into relay) and inject currents according to relay's formula:
Ia=5A Ib=5A Ic=xA. For example x=0A dI=100%.
If you have only single phase injection: Sverker 650/750/760
you can start inject from some current before set-point and slowly increase injection up-to set-pint.
For example setting dI is 20%, for 5A Inom=1A.
Hope is help.
Regards.
Slava

 

[slavag]

OOPS, forgot. Possible also other option.
I2 or NPS or 46 principle.
In this case you can use very simple method of test
you connect three-phase current to relay , but in reverse seq. Ia Ic Ib and start injection from current below setting, see my post above.
Regards.
Slava

 

[521AB]

Guys,
I think you should start a new thread for broken conductor