Re-called to a job today.
(Hate it when that happens)
Motor overloads tripping on a 3ph. water pressure boost pump, but intermittently, not every day.
First visit, tested everything - current draw, voltage, winding resistances, IR etc - nothing,
no trips, everything working fine, like your car when you take it into the garage 'cos its running rough and then it purrs like a kitten, the swine ( the car, not you TC)
Put it down to the pump struggling to force water round the system, because it's a big house, and turned the O/L's up a bit - see how that goes.
Anyway, today its a bit different, clamped it and the current is fluctuating from 4+ to 6+ Amps, the pitch of the motor changed at the same time, sounds like it's losing a phase so checked it from that angle. turns out one of the line connections between the contactor and the O/L unit is burned and losing contact. cleaned it up, OK now, must have been a loose connection.
The pump/motor set including the base plate, Pressure switch, enclosure with MCB, RCD, Contactor and overloads was supplied and installed by the plumbers as a pre-wired unit, all I had to do at the time was to run a supply to it.
When I explained to my customer what the problem was, he said, didn't you check all the connections were tight when you installed it? Ouch, well yes, all the connections I made were tight, but this unit was supplied by others, quality control stickers on it, so would I be expected to go through someone else's work and check it?
Nevertheless his question stung a little, feel I should have spotted it first time, spent two apprentice weeks every Manchester Wakes tightening dist. board connections on shutdown planned maintenance.
So what do you all think, should we check connections made in supplied equipment? I normally check light fittings etc. but a whole panel? not charged him yet and not sure if I should.
(Hate it when that happens)
Motor overloads tripping on a 3ph. water pressure boost pump, but intermittently, not every day.
First visit, tested everything - current draw, voltage, winding resistances, IR etc - nothing,
no trips, everything working fine, like your car when you take it into the garage 'cos its running rough and then it purrs like a kitten, the swine ( the car, not you TC)
Put it down to the pump struggling to force water round the system, because it's a big house, and turned the O/L's up a bit - see how that goes.
Anyway, today its a bit different, clamped it and the current is fluctuating from 4+ to 6+ Amps, the pitch of the motor changed at the same time, sounds like it's losing a phase so checked it from that angle. turns out one of the line connections between the contactor and the O/L unit is burned and losing contact. cleaned it up, OK now, must have been a loose connection.
The pump/motor set including the base plate, Pressure switch, enclosure with MCB, RCD, Contactor and overloads was supplied and installed by the plumbers as a pre-wired unit, all I had to do at the time was to run a supply to it.
When I explained to my customer what the problem was, he said, didn't you check all the connections were tight when you installed it? Ouch, well yes, all the connections I made were tight, but this unit was supplied by others, quality control stickers on it, so would I be expected to go through someone else's work and check it?
Nevertheless his question stung a little, feel I should have spotted it first time, spent two apprentice weeks every Manchester Wakes tightening dist. board connections on shutdown planned maintenance.
So what do you all think, should we check connections made in supplied equipment? I normally check light fittings etc. but a whole panel? not charged him yet and not sure if I should.
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