Connections to a pump motor.

[Amp David]

I have a pump that has basically been ripped of a folding machine, no cable, instructions, diagrams left for me. What would the two black wires normally be used for. The motor is 3 phase, and the brass links are set for star so was thinking would they be the nuetral?
Any help and suggestions welcome

 

[gaz101]

may be over temp sw
or centfugal start sw

 

[Amp David]

Just been given a stack of papers in which there is a wiring diagram. It shows it as being a thermal sensor. Would this mean having to use a 6 core cable to the pump.

I'll scan the page in and post it.

 

[Amp David]

 

[gaz101]

thermal sensor goes in series with stop/overload

3 phase cables
1 cpc cable
2 cables for thermal sensor

 

[Darkwood]

The thermal switch is optional normally and allows for an extra degree of protection, if it wasnt wired in before i dont see reason to now although assuming the motor has overload protection already all the thermal cutout will do is cut power before damage is caused to the winding if say the motor ran too hot as the overload may not see this until the winding overheat, this could occur if the impellor was broken or the motor air flow was restricted by something hence it overheats, you have to way up the risk of this and the consequences if it occured.
Obviously the thermal switch needs to be part of the stop or e-stop circuit to shut the motor down.

 

[benji]

thermistor control unit needed ,i would leave alone

yours benji

 

[jpmiff]

Hi

the two black wires will be for a thermister which is built into the motor windings, for this to be used in your motor control circuit you will need a thermister relay which has a contact which the control voltage is disconnected to the control in the event the motor gets too hot and protects it from overheating, dropping out the motor contactor.
The pump would run without this safety feature but may overheat and fail for obvious reasons.
the three phase is wired in the normal way.

 

[Amp David]

Nice one guys. Looking at the 2nd picture in post 4, am i correct in saying that the thermal overload will be taken back to terminals 32 and 33 in the machines wiring panel?

 

[silva.foxx]

yes, you're correct.

 

[Amp David]

How would the conductor to the thermal control switch be identified usually?

 

[pmac10]

i dont think there is a 'normal', in our factory all control wiring is orange sheathed and this is what i would use for thermistor monitoring, a few points ive picked up using thermistor monitoring relays, if star/delta motor, ensure the control circuit doesnt allow the motor to restart in delta after cooling and ive found it beneficial to wire a time delay so as the motor doesnt start as soon as the windings drop below the temperature threshold as 'cycling' will ocurr, ie, your winding temp will float above and below the thermistor cut out and stopping and starting the motor will aggravate your problem.

 

[Amp David]

This may be a simple question to most of you but here goes. Looking at the diagram I have, it seem as though the wrong set of terminals are linked out (as supplied).

Which set would I connect my L1 L2 L3 to? The linked or the non linked?

Thanks again people

 

[pmac10]

non linked, likely labelled u1,v1,w1, will still work if these are your star point and you connect to u2,v2,w2

 

[Amp David]

Thank pmac