3 Phase power

[mikeexpress]

Im trying to find a device that will tell me when i have single phased power before i burn any motors. Last nite i had a power outage and all seemed fine but i found out i had lost 1 phase of power. That was not untill 2hrs later.but all equipment was running.

 

[pitzerwm]

I had a PLC running/checking everything, but the bottom line is I used a relay on each leg, if one dropped it killed all motor circuits. At least put a "light" on each leg, then you would see if it was out.

 

[Rudy]

After a lightning strike took out an ACW controller, and about $1500 additional miscellaneous devices, I bought an industrial grade "surge protector". This device guards all three phases, and has panel lights to show that the A, B, and C phases are powered.

It also has relay outputs that trigger if any of the phases go bad.

It would be nice to wire it so that the MAIN cuts off if any of the phases drop off, but that would require a very expensive motorized disconnect. For now, we use the device for surge protection only, and also as a way to visually see that all three legs are powered.

BTW, I got this ($700???) device on EBay for $150.....so keep your eyes peeled.

 

[dogwasher]

Phase monitors are about $90.00

Not sure if that would work on a ACW but wire them into your motor starters and they will drop out the power and tell you some details on the the time it happened and the voltage that was monitored

 

[bigleo48]

If you have a monitored alarm system, use some relays that connect to their panel and have them activate the contacts. Then they can call when you drop power or a phase. Cheap solution, but I like bill's solution better.

 

[Jeff_L]

I had a PLC running/checking everything, but the bottom line is I used a relay on each leg, if one dropped it killed all motor circuits. At least put a "light" on each leg, then you would see if it was out.

This is what I do as well. Kills all three legs if one were to die.

I also wonder if you couldn't just set the amps on your motor starter to just above the minimum. That way when a leg dropped the amp pull would be more on the other two legs which would trip it? Just a thought, probably not a good solution though, but might get someone cash strapped by for awhile.

 

[bigleo48]

This is what I do as well. Kills all three legs if one were to die.

I also wonder if you couldn't just set the amps on your motor starter to just above the minimum. That way when a leg dropped the amp pull would be more on the other two legs which would trip it? Just a thought, probably not a good solution though, but might get someone cash strapped by for awhile.

That should always be the case...for example my SS pump motors are set for 6 amps, so if one leg is missing, it trips due to the amp draw increase on the others.

 

[mjwalsh]

Phase monitors are about $90.00

Not sure if that would work on a ACW but wire them into your motor starters and they will drop out the power and tell you some details on the the time it happened and the voltage that was monitored

dogwasher,

Can you post the brand & model # of this particular phase monitor that you are using? Also a vendor that will sell it to us direct.

I found one at the following link:

http://www.automationdirect.com/adc...l_Relays/Phase_Monitoring_Relays/PMRU-1C-480A

It seems like the phase monitor use is a better approach than a PLC unless we have the expertise to know the threshold where the partial loss of full voltage would actually hurt the motor &/or other components that it was protecting etc.

MJ

 

[Earl Weiss]

Im trying to find a device that will tell me when i have single phased power before i burn any motors. Last nite i had a power outage and all seemed fine but i found out i had lost 1 phase of power. That was not untill 2hrs later.but all equipment was running.

Same happened to me Sat. Night. Wasn't fixed until Monday at 10:30 am. Still have 2 bys down and wrking to figure out if something single pahsed and is messed up or if there was a surge.

 

[MEP001]

I also wonder if you couldn't just set the amps on your motor starter to just above the minimum.

That's exactly how it should be set. If everything is working properly it should never trip under normal operating conditions. If one leg is dropped, it should trip quickly enough that it won't damage anything. I wire self-serve equipment to kill all the 24V to a bay so if the motor trips the coin acceptor is also shut off and no one loses any more money.