code interpretation

[foot]

This may seem like an easy question to some, but I need a little clarity on it. 430.32(A)(1) Separate Overload Device, and 430.32(C) confuse me a little. I've missed a couple questions on which figures to use, are there key words I'm missing. If the question says the service factor is 1.15 or greater, which % do I use? Thanks for any help on this.

P.S. Am I the only one that messes this one up??!!

 

[raider1]

What 430.32(A)(1) is saying is that for motors more that 1 HP a separate overload device is permitted to be used and the setting of this device shall be rated no more that the percentages listed.

In your example of a motor with a marked service factor of 1.15 or greater you must use 125%.

Now 430.32(C) says where the sensing element or setting of the overload relay is not sufficient to start the motor or to carry the load, higher size sensing elements or incremental settings shall be permitted to be used, provided the trip current of the overload relay does not exceed the percentages of full-load current.

Now in your example if the 125% setting of the overload device was to low to allow the motor to start, then you are allow to increase the size of the overload device but not more that 140% of the motor nameplate full-load current.

Hope this makes sense.

Chris

 

[foot]

code interpretation

I understand the use of 430.32(C) when the first overload isn't holding, what gets me is the questions I've been studying(Mike Holt Master calc's) that don't come and say that the first overload isn't holding, but when I do the figures and check my answer it's wrong, because the other % was used, and of course both answers are there to choose.

 

[foot]

code interpretation

Well I've read and re-read, and what I think is the answer, is "maximum" and "minimum". Is it that simple?? Someone tell me!! Thanks