3 phase motor question

[kmart]

I recently purchased a new motor for a fluid pump application to replace a 6 year old motor. All of my motors here are 3 phase and all simply have 3 leads coming from the motor. This new motor has 6 leads T1,T2,T3,T4,T5,T6. When I asked my supplier how it should be wired, he told me to wire T4, T5, & T6 together & T1, T2, T3 to the power leads. Did this, tested, checked rotation and all was fine. Put to load & 1/2 hour later, motor overheated & shut down. After cooling, would not restart & repeatedly tripped power supply breaker. The motor in question is a hyundai, 30 HP, 575 volt, 1770 rpm, 29 amp rating. S.F. 1.15. Tested voltage at feed and each leg reads 230 volts. Can anyone tell me what might have happened? Faulty motor, or incorrect wiring? thanks in advance

 

[HUNJAN]

you need to connect this motor in delta-- if your incoming voltage is 230v 3phase..

 

[alehman]

Your motor is rated 575 volts, but your supply is 230 volts?
Am I missing something? If this is the situation, I can see why it failed. The motor voltage must match (or at least be close) the supply voltage. If the supply voltage is too low, it will draw too much current and overheat.

Perhaps your motor is rated for multiple supply voltages (many are). If one of the rated voltages matches your supply, you need to connect the terminals in the configuration shown on the nameplate for the supply voltage.

Do you have overload protection for the motor? If so, it apparently didn't work.

 

[kmart]

My power source is 600 volts, each lead (separately) reads 220 (type-o in original post) volts per lead for a total power supply of 660 volts.

 

[jraef]

Something is still not right. If you have 600V, you should be abkle to read 600V from phase to phase. Your phase to ground voltage is irrelevant, but 220V phase to ground is a little low as well.

If you are referring to your phase to phase voltagfe being 220V, then you have 220V 3 phase. You do not add them together to get 660V!

And if you are not in Canada, the chances of you having a 600V service are practically nil.

"Venditori de oleum-vipera non vigere excordis populi"

 

[kmart]

Sorry, the voltages I measured are phase to ground. Phase to phase voltage is 600 volts, and yes I am in Canada running a 600 volt SCR system. this being said, is my wiring of the motor incorrect? The motor has an auto-reset overload, but obviously must have failed.

 

[Barry1961]

Sounds like it is wired correctly.

What went wrong with the 6 yr old motor? You may have a pump problem or some how the load has increased. Has the pressure or flow changed recently?

Your phase to phase voltage needs to be balanced also or it will cause overheating. When you put another motor in check the amp draw on each phase.

Barry1961

 

[kmart]

Bearings went on old motor, pump is only about a month old,and spins freely. These motors run on average 20 hours per day,constantly stopping and starting, so a 6 year life span is exceptional. Pressure and flow has stayed the same. I will check for phase to phase balancing and post results.

 

[itsmoked]

kmart; Sorry to hear of your motor fatality. All I can add is you should probably ALWAYS monitor the running load current on any new motor install. That way you will know for sure that you are not over loading your motor because of pulley sizes being wrong or the load is bigger than expected, etc.

 

[kmart]

Ok phase to phase voltages after breaker are equal at 580 volts. Just to note that this motor is direct start, so in reading other posts I think I should have wired in Delta (T1&T6 TO L1, T2&T4 TO L2, T3&T5 TO L3). Does this make sense? Or does it really matter?

 

[jraef]

Yes.
575V motors are single voltage Delta wound, and are to be connected as follows:
L1 to 1 & 6
L2 to 2 & 4
L3 to 3 & 5

That is right out of the book.

The other connection would have given you a wye connection, which would only produce 1/3 torque.

"Venditori de oleum-vipera non vigere excordis populi"