With most "typical" dc coil applications (< 1amp) I've encountered, a diode is connected across the coil (directly to the supply) to absorb the surge when the coil is de-energized. I ran across an application where DC power was being switched (both + & -) through another relay. The diode was...
I have a 50 HP 3-phase, 460VAC motor circuit that experienced a fault. The motor is operated by an across-the-line starter. (I didn't realized motor starters had so much smoke compacted into them!). A megger test did not show any difference in the windings or wiring to the motor so the motor...
I am looking at a grinding system that occasionaly gets jammed and stalls the motor (100 hp, 3-phase, 460VAC). The thought is to monitor the current in one of the motor legs, upon sensing an over current condition, stopping the motor, reversing the direction to clear the jam, stopping the motor...
Many of the specifications (Hevi-Duty, Acme) I have looked at specifically say 60 Hz operation only. However, postings on this site indicate that if the input voltage is reduced by 5/6, it is perfectly fine to use them at 50 Hz. Theoretically , it is plausible but are there any other things to...
I have a 3-phase, 440VAC, 50 Hz line supply (from a portable generator), with a load that can operate either on 380, 400, or 415, 50 Hz. I am hoping to find a "off the shelf" transformer here in the US that will step down the voltage to one of these levels. Is one of the above a better choice...
What is the "industrial standard" wire insulation color for DC motor (90VDC or 180 VDC) leads? I've seen some places that use black and others that use blue. Are both leads the same color? Are the field & armature all the same color? Thanks
A requirement of UL508A is to establish the "short circuit current (kA symetrical" of a control panel. Their procedure to accomplish this is pretty detailed. My question is if I have a disconnect - short circuit rated at 200kA - with class CC fuses rated at 100kA, would the short circuit...
