Motor protection

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Wiloinge

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According to the NEC, for three-phase motors ground fault protection is sized according to table 430.52, and for overloads 430.32(A)(1) is used; Reviewing other information I see that there is table 6 of the IEEE C37.13 that also indicates motor protection, please tell me what considerations should I take into account to choose between what is indicated in the NEC or the IEEE C37.13?
 
Thank you very much for answering, taking what is stated by the NEC, I will have the devices separately, if I have both functions in a single element. What consideration should I take into account when sizing a thermomagnetic device?
 
I am not aware of any thermal magnetic breaker that can provide both the short circuit and ground fault protection, as well as overload protection. The best device for this is a listed combination starter that will have the ground fault and short circuit protection, the motor contactor, and the overload protective device.
 
Thank you very much for answering, taking what is stated by the NEC, I will have the devices separately, if I have both functions in a single element. What consideration should I take into account when sizing a thermomagnetic device?
There is no reason that both functions cannot be in the same device. In fact, that is becoming more and more common.

The code tells you what the maximum rating of a TM breaker can be. It can of course be smaller. It would be unwise to make the rating low enough that it reguslarly opens under normal conditions though.
 
I am not aware of any thermal magnetic breaker that can provide both the short circuit and ground fault protection, as well as overload protection. The best device for this is a listed combination starter that will have the ground fault and short circuit protection, the motor contactor, and the overload protective device.
motor protection circuit breakers do this. i generally use ab 140M MPCBs but there are a bunch of manufacturers that make them.

no reason to waste money on a combination starter unless there is some reason to do so.
 
motor protection circuit breakers do this. i generally use ab 140M MPCBs but there are a bunch of manufacturers that make them.

no reason to waste money on a combination starter unless there is some reason to do so.
Was not aware of those. Are they combination protection and a manual motor starter?
My work was mostly industrial and don't think I ever connected a motor that was not connected to a starter, and the vast majority of those starters were combination started MCC buckets.
 
Was not aware of those. Are they combination protection and a manual motor starter?
My work was mostly industrial and don't think I ever connected a motor that was not connected to a starter, and the vast majority of those starters were combination started MCC buckets.
Usually the mpcb is wired to a contactor so it is in effect a combination starter incorporating disconnecting means, sc protection, overload protection, and a contactor to turn the motor on and off. Very cost effective.

Not a lot of people wasting money on mccs these days if there is no good reason to do so. I bet we do ten or twenty times as many motors this way as opposed to mccs.
 
Was not aware of those. Are they combination protection and a manual motor starter?
My work was mostly industrial and don't think I ever connected a motor that was not connected to a starter, and the vast majority of those starters were combination started MCC buckets.
I’ve used them two ways: in combination with a contactor because it needs remote control, or all by themselves because the process was manual anyway.

I once built a barge with 40 x 100HP pumps on it to float in a reservoir that had dropped below the intake for a water system. The pumps were going to run non-stop until the rains returned. Each pump had nothing but an MPCB with an adjustable thermal trip, and an Under Voltage Release so that they didn’t all automatically restart after a power failure. Super low cost option compared to full blown Size 4 Combo starters.
 
Usually the mpcb is wired to a contactor so it is in effect a combination starter incorporating disconnecting means, sc protection, overload protection, and a contactor to turn the motor on and off. Very cost effective.

Not a lot of people wasting money on mccs these days if there is no good reason to do so. I bet we do ten or twenty times as many motors this way as opposed to mccs.
I guess it makes a difference what you are working on and the type of facility the motors are in. Have done a few local control panels for packaging equipment that had IEC contactors, but the vast majority of the motors in the industrial plants I have worked in are supplied from MCC buckets.
 
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