unbalance 3 phase

[edlincoln]

I have a Lennox PRA 2.5 going off on water pump amperage overload. It happens when no one is looking!
The phase to phase vac jumps around when the compressor or fan shift on or off and speed of condenser fan changes. So the amperage on one leg of the water pumps goes out of the 10% normal unbalance.
Will I find a lose screw terminal? or ???? please give me some suggestion.

[mbc]

how about if you turn all compressor and fans off ? in this case do you have unbalance Amp. ? If yes your water pump motor should be checked .
If NO check wiring and also N wires and connect the N wire to your water pump motor and check conection between your N wier with main N wire.
you can find your unbalance with checking Amp. 3 phase and also N.

unbalanceing might coms from lose screw or you use 1 or 2 line more than
other one and your N wire is not conected to main N

[mbc]

So it effect to you 3 phase system (( special star running motors)) or damageing of motor wires ( more common %99)

[frank]

If it's always been happening this way then I would look at the size of the incoming cable.
If it is under sized for the normal running current you may be experiencing severe volt drop conditions.

More than likely though, your 3 phase water pump is breaking down.

have you tested it for earth leakage?

[goshen]

hi either a loose terminal or undervoltage or a pump motor letting u know it is time for replacment
i would first check for a loose connection on the feed side not the motor then if all is ok check the cabling and motor

[edlincoln]

Thank for all your suggestions. I should mention the chiller is running off a 2-3 phase converter.

[nike123]

Ştatic or rotary?

[edlincoln]

rotary, standalone

[nike123]

rotary, standalone
You need to have double size nominal power of rotary converter in relation to max absorbed power off your Lenox.
Do you have enough nominal power of converter?

[D.D.KORANNE]

Observe which phase dips below 10% of the voltage value & trace back ..usually if the voltage dip is unlikely only in one phase unless it is in problem like wire , terminal ,loose , burnt up connection holding on to to terminal , contactor terminals pitted etc.