I have been asked a question I did not know the answer to. 430.6 states that (In the 2005 NEC handbook page 555) T1, T2, T3, T4, T5, and T6 leads to the motor on a wye start delta run are sized at 58% of the full load. Where does it say how to size the overloads on the main run contactor and why are they only on T1, T2, and T3?
Article 430.6
- Thread starter Sparkypf
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buldogg
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- Green Bay, Wisc.
The starting circuit should drop out and the circuit should be in the run circuit way before the overloads will have a chance to open up.
Sparkypf said:
Article 430.32(A)1
(1) Separate Overload Device A separate overload device that is responsive to motor current. This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate full-load current rating:
Motors with a marked service factor 1.15 or greater 125%
Motors with a marked temperature rise 40?C or less 125%
All other motors 115%
Modification of this value shall be permitted as provided in 430.32(C). For a multispeed motor, each winding connection shall be considered separately.
Where a separate motor overload device is connected so that it does not carry the total current designated on the motor nameplate, such as for wye-delta starting, the proper percentage of nameplate current applying to the selection or setting of the overload device shall be clearly designated on the equipment, or the manufacturer's selection table shall take this into account.
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