Motor circuit protection

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coryp

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I am using a allen bradley motor circuit protector (140M type) on a 1.5 hp motor listed at 3.0 amps. The short circuit setting is adjustable from 4 - 6.3 amps.

What is the maximim I can set this device?

Do I treat this like a dual element fuse in Table 430.52 and set at 175% of motor fla or can I set at 6.3 amps?
 
The max setting is 250% of FLA per table 430.52... so if FLA is 3A the MAX setting would be 7.5A .... I normally set the trip point based on inrush current of motor under normal load.
 
No. The overload device is set to the nameplate of the motor. No calculations needed on this one.

If you want to set the trip point to the inrush current you need a much BIGGER overload relay.
Adjustable overload relays are designed so that you just set it to nameplate.
 
John Valdes said:
No. The overload device is set to the nameplate of the motor. No calculations needed on this one.

If you want to set the trip point to the inrush current you need a much BIGGER overload relay.
Adjustable overload relays are designed so that you just set it to nameplate.
Click to expand...

John,
I believe the 140M is a "motor circuit protector" to provide GFSC protection and, according to A-B, is to "be used in conjunction with overload protection"
 
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