transformer

[tomnoel]

can anyone tell me what are the implictions of turning off the instantaneous earth settings of a transformer feeder.:hanged:

 

[Engineer54]

I think you first need to tell us Why, ...you want to turn this instantaneous earth setting off, for a transformer feeder breaker!! It sounds to me, that you have some sort of earth fault on this feeder??

 

[Knobhead]

I’m getting a horrible feeling about this.

 

[oldtimer]

This sounds like how do I switch off a burglar alarm question

 

[Darkwood]

Next Question.... how long should i perform CPR on my work collegue before i give it up a no hoper!...

 

[shadewakka]

Next Question.... how long should i perform CPR on my work collegue before i give it up a no hoper!...

Depends how much you really liked him in the beginning....:46:

 

[Engineer54]

When you say ''Transformer Feeder'' what are you referring to the MV side or the LV side of things?? I'm assuming your talking about the LV side, but best to confirm.... lol!!

Come on tomnoel, What problems are you having with this feeder breaker, for you to want to negate the earth fault protection from this breaker???

 

[Knobhead]

With out giving some clarification how can anyone give an answer?

 

[tomnoel]

When you say ''Transformer Feeder'' what are you referring to the MV side or the LV side of things?? I'm assuming your talking about the LV side, but best to confirm.... lol!!

Come on tomnoel, What problems are you having with this feeder breaker, for you to want to negate the earth fault protection from this breaker???

During recent testing our TX feeders tripped on inrush To over come this it has been suggested that we turn off the Instantaneous Earth Fault Setting on the TX feeders and still achieve grading with the UKPN relay at the max earth fault setting of 1.5KA. Any Comments.

 

[Engineer54]

During recent testing our TX feeders tripped on inrush To over come this it has been suggested that we turn off the Instantaneous Earth Fault Setting on the TX feeders and still achieve grading with the UKPN relay at the max earth fault setting of 1.5KA. Any Comments.

Can you give us a better breakdown of the system your talking about and it's age. A nice photo of the breaker(s) and it's electronic protection unit, along with any other protection relays you have on this circuit, would also help me to advise you. From what little you have stated, this sounds more of a bodge rather than a fix!! lol!! All Instantaneous protection elements, including earth fault settings also normally come with a time (delay) setting.... which would/should cover any inrush cycle. Not sure what your grading with/against, using the relay max earth fault setting.

I'll also ask again, are we talking about the MV side or the LV side?? I ask because i'm beginning to think your talking about the MV side of things, as TX feeders will be the main incomers on the LV side of things, and wouldn't see inrush... But sometimes terminology can be confusing!! lol!! By the way, who has advised/suggested turning off the instantaneous element of your earth fault protection???

Another thought, ...any chance of posting a very simple one line drawing showing the protection relay positions, hand drawn is fine!!

 

[Knobhead]

I can’t see how inrush is showing as earth fault, instantaneous overload maybe. As E54 has asked is this the MV or LV side that the fault is being detected. An incorrectly set restricted earth fault on the LV side is a possibility, but it’s a remote one.

Who has recommended disabling the earth fault, it’s not something you would do as a permanent fix. Can the time lag be adjusted?

One last question, is this a new fault or a long running sarga.

 

[Engineer54]

I can’t see how inrush is showing as earth fault, instantaneous overload maybe. As E54 has asked is this the MV or LV side that the fault is being detected. An incorrectly set restricted earth fault on the LV side is a possibility, but it’s a remote one.

Who has recommended disabling the earth fault, it’s not something you would do as a permanent fix. Can the time lag be adjusted?

One last question, is this a new fault or a long running sarga.

Much better put than i Tony, ...but then i'm in holiday mode!!! lol!!!

Some of the older TX,s that's been in service for a good many years, can have problems with EF during times of inrush, but generally nothing that can't be protected against, depending of course on what protection relays are incorporated in the system. Even R/E relays have a suitable time delay... lol!!