Contactor faulty?

[kmaccui]

i popped in on friday and found

1 phase at 5.4 amps

2 phase at 5.2 amps

3 phase at 10.8 amps (the problem phase)

so i moved the cables to a spare way it was a 4 phase contactor and it dropped down to 7.8 amps

i asked the mechanics to keep an eye on it (yeah i know fat chance) and we will pop in on tuesday to check.

it was going 1-2 times a day they said but not everyday

all connections at board and contactor were tight when checked

 

[kmaccui]

i popped in on friday and found

1 phase at 5.4 amps

2 phase at 5.2 amps

3 phase at 10.8 amps (the problem phase)

so i moved the cables to a spare way it was a 4 phase contactor and it dropped down to 7.8 amps

i asked the mechanics to keep an eye on it (yeah i know fat chance) and we will pop in on tuesday to check.

it was going 1-2 times a day they said but not everyday

all connections at board and contactor were tight when checked

 

[Sidewinder]

kmaccui,

BTWE we call them poles in a contactor, but, you need to be sure the 4th pole is fully rated, "some" are only an n/o auxilliary contact which will not carry as much current as the main 3 poles.

Check the terminal identification, the main contacts will be labelled 1,2,3,4,5,6, &/or, L1, L2, L3, T1, T2, T3.

An auxilliary will normally be a 2 digit numer e.g. 11, 12, 21, 22 etc.

Is this the middle mcb of the 3? If so the mcb could be going on thermal as it is carrying the higher current and this is "insulated" by the adjacent devices.

IIRC there is a "standard" derating factor for mcb's near their flc when in banks, would need to check that though.

HTH

 

[Sidewinder]

kmaccui,

BTWE we call them poles in a contactor, but, you need to be sure the 4th pole is fully rated, "some" are only an n/o auxilliary contact which will not carry as much current as the main 3 poles.

Check the terminal identification, the main contacts will be labelled 1,2,3,4,5,6, &/or, L1, L2, L3, T1, T2, T3.

An auxilliary will normally be a 2 digit numer e.g. 11, 12, 21, 22 etc.

Is this the middle mcb of the 3? If so the mcb could be going on thermal as it is carrying the higher current and this is "insulated" by the adjacent devices.

IIRC there is a "standard" derating factor for mcb's near their flc when in banks, would need to check that though.

HTH

 

[kmaccui]

thanks sidewinder if i remember it was L4 does that sound right? hope it was not 14

yes it was the middle pole but i changed the mcb and it still happened so really hoping it is the middle pole on the contactor causing the problem.

thanks

 

[kmaccui]

thanks sidewinder if i remember it was L4 does that sound right? hope it was not 14

yes it was the middle pole but i changed the mcb and it still happened so really hoping it is the middle pole on the contactor causing the problem.

thanks

 

[kmaccui]

thanks for the help guys it turned out to be the middle pole of the contactor causing the problem

 

[revjames]

I beg to differ, seen plenty with one phase badly arced and giving the type of symptoms described.

"thanks for the help guys it turned out to be the middle pole of the contactor causing the problem "

Not going to say 'told ya'....... :innocent

 

[Evans Electric]

Nor me ! :innocent There you go , lighting problem in Glasgow solved without leaving Brum ( see post 7) Now is there a "blowing your own trumpet" smiley ? ; )

 

[kmaccui]

watch the big heads you might not be able to leave the house soon guys. lmao