mccb tripping

[dave-gardiner]

horticultral lighting circuit - 14 x t/p 16A mcb's each mcb has 6 x 600w 400v son lights, fed from a contactor which is fed by a 160A merlin gerin mccb. across the contactor measures L1 - 130A L2 - 133A L3 - 132A but after 6hrs the 160A trips. any ideas ? there is another 2 identical systems in the same cabinet working ok. system has worked ok for last 12 months.

 

[Guest123]

Does the 160A MCCB have an adjustable thermal element that may be set slightly too low???

 

[dave-gardiner]

the setting is set on the dial is set at 1 which I take is 160 A.

 

[Engineer54]

Does the 160A MCCB have an adjustable thermal element that may be set slightly too low???

That is certainly worth checking, the adjustable dial should be set to x .9, if set at x .8 or lower it will trip.....

 

[dave-gardiner]

set at x 1

 

[Engineer54]

What model breaker do you have ??

 

[GLENNSPARK]

I take it these are "selective" types (for time and current) eng?.....

 

[dave-gardiner]

merin gerin n160

 

[Engineer54]

Yes, ....Some MCCBs are totally adjustable, others can just be adjustable on time delay.

 

[dave-gardiner]

current only

 

[Engineer54]

merin gerin n160

Need to know the designation letter after frame size N 160 (L) (H) (M) (E)

 

[Engineer54]

Haven't got my reference stuff at home ...so i'm going to have to look on line...

 

[dave-gardiner]

sorry not at work at present to look at details of mccb. but again has been working fine for over a year.

 

[GLENNSPARK]

I have only seen these on youtube but from that have managed to get a grasp of what they are about but i would like more knowledge of them so i will be sure to ask the lecturers about them at college.....

 

[Engineer54]

Can't get onto the website!!!! What have you checked so far mate? Do you own an Amp Meter, and measured the actual current draw from these fittings? MG MCCBs are generally good very reliable units, but like everything else they can fail. You may very well have a unit where the adjustable element is U/S... Before anything else check those light fittings, one or more may have a ballast or starter that is in the early stages of going down!!!