amperage draw 7.5 hp comp. motor 1

[turboranger]

hello. new 7.5 hp compressor motor. trips magnetic switch intermittantly.
-32amp run rated.
-runs at (35amps-235v) . starts at (150amps-205)fuctuates 5-10 %.
-its was (175amps-190v)on start until I ran new wire from fuse box to comp.
-1960 building stucture.old wiring
-is 205v to big of a voltage drop on start. ?????
-or is the comp. drawing to much.???
-capacitors passed ohmn metor test

any suggestions. thanks george

 

[rbulsara]

What is the rating of Mag switch? What is the setting of mag trip?

Starting current of 6-7 times would be considered normal. Your mag-trip must accomodate that. Have you looked at table 430.52 in NEC?

 

[rovineye]

What is the overload device set at? It can be as high as 125% of motor full load amperage if the motor has a service factor of 1.15 or more, or has a marked temperature rise of 40 deg C or more. If not, it should be not more than 115%. NEC 430.32 (B)(1).

Voltage drop depends on how long it stays down, but it doesn't look bad for short duration.

 

[turboranger]

Thanks for your replys. Your the greatest, love learning. You steered me in the right direction. (NEC)all is to code and specs. Just bumped up the trip setting slightly. thank george.