Another genset question

[John-]

Hi.

excuse my ignorance. I have seen this before. Why is the phase in this picture taken through two of the poles in this manner?

the isolator is wired in exactly the same way with the phase going through line contact out the top and back through another pole.

what am i missing please?

thanks

john

 

[James]

Hi.

excuse my ignorance. I have seen this before. Why is the phase in this picture taken through two of the poles in this manner?

the isolator is wired in exactly the same way with the phase going through line contact out the top and back through another pole.

what am i missing please?

thanks

john

You might have forgotten to add the picture.

 

[Darkwood]

Without the pic' as expressed it might be difficult to respond although if we are talking about a 3 pole contactor with overload then it may be the overload monitors 3 poles and has balance and/or loss protection so in the case of single phase you have line and neutral and an empty pole, looping the line gives an output on each pole for the overload to recognise...... if it's not this then need that pic.

 

[John-]

Without the pic' as expressed it might be difficult to respond although if we are talking about a 3 pole contactor with overload then it may be the overload monitors 3 poles and has balance and/or loss protection so in the case of single phase you have line and neutral and an empty pole, looping the line gives an output on each pole for the overload to recognise...... if it's not this then need that pic.

Ohhhh bugggah. Sorry. Attached now

 

[John-]

Ohhhh bugggah. Sorry. Attached now

 

[Darkwood]

Without details of the actual breaker we cannot be sure but most 3ph mcb's do not give balance monitoring so this is purely for redundancy, they could have easily just fitted a 2 pole option here, however if the breaker has phase loss monitoring then that is why, the schematic symbol used in each pole does not suggest that is the case so I think it is just convenient redundancy or the designer doesn't fully understand the functional concept of a MCB.

 

[Rockingit]

Without details of the actual breaker we cannot be sure but most 3ph mcb's do not give balance monitoring so this is purely for redundancy, they could have easily just fitted a 2 pole option here, however if the breaker has phase loss monitoring then that is why, the schematic symbol used in each pole does not suggest that is the case so I think it is just convenient redundancy or the designer doesn't fully understand the functional concept of a MCB.

Agreed - strikes me that it's not an MCB but just an isolator, though why you'd spec a 3p when a standard 2p would do it beats me.

 

[John-]

Without details of the actual breaker we cannot be sure but most 3ph mcb's do not give balance monitoring so this is purely for redundancy, they could have easily just fitted a 2 pole option here, however if the breaker has phase loss monitoring then that is why, the schematic symbol used in each pole does not suggest that is the case so I think it is just convenient redundancy or the designer doesn't fully understand the functional concept of a MCB.

Thanks for the comment. It is single phase. And why did the installer fo the sane in the 3 pole isolatet located a few feet away?

 

[Rockingit]

That's a new one on me! Totally pointless.

 

[Darkwood]

Our replies would be better if the schematic reflected the actual install, that is not a circuit breaker as denoted on the schematic, that is an isolator, having said that if the cover is yellow it will denote it is for emergency isolation, in said cases where possible it is good practice to utilise spare poles for redundancy in these circumstances but it shows poor initial design if deliberately done in design, many of these isolators are off the shelf and they tend to stock 3 or 4 pole so purchase convenience is often the reason we have spare poles.
Without seeing the whole schematic or down stream devices I cannot comment on whether the isolator should actually be a circuit breaker in this case.