What side bands do I look for when analyzing a 3600RPM 500HP 480V refrigeration motor. The problem is intermittent but it is an old motor which has been rebuilt at least three times.
Question: A 12 wire 500HP refregeration motor which is labeled wye/delta and is really a wyewye/deltadelta motor, once seven seconds have passed and the electronics has determined that there is nothing wrong with the motor it adavnces to deltadelta with a phase reversal. Does the phase reversal...
I am having trouble understanding the current of a three phase motor. Say I have a 500HP Y/D refrigeration motor with overload protection. The overload protection is sensed by T1. T1 pulls 520A, T2 pulls 550A and T3 pulls 570A at full load. FLA=570A, 460V with a service factor of 1.5. It seems...
Sirs, I am going to ask a question which has been bugging me for a long time. Since I have seen Latin used on this post and I could not find a Lawyer's forum, I thought I would give it a try. What is "Expo Facto Law"? I have found that it means "after the fact". This definition is incomplete...
Sirs, I have some long tubular flourscent light fixtures which I need to hang in a difficult area. I have an idea which through a prototype works fine. I have ran 3/4" conduit which is supported by I beams every six feet. I suspended a 100" tubular light fixture from the conduit. This fixture is...
Sirs, I have a heat exchanger which is being used as a hot water heater for a tray washer. It has been undersized since installation. I have contacted the manufacturer and the only response I have received is for them to offer to send out a salesman. We do not want to replace this unit and have...
Sirs, If I have a 400HP 480VAC FLA 450A induction three phase motor operating at a no load conditon. What would be the app. current drawn? The shaft is free rotating. Thank You
I accidently installed a piece of galvanized water pipe in a conduit run. I did not notice the red printing on the side of the pipe. I am sure this pipe has a higher strength rating than regular rigid conduit. Is this a violation of the NEC?
If I have a unknown AC voltage impressed on a purely resistive circuit and wish to know the RMS value of this voltage but do not have a meter. In theory, if I measure the temperature of the resistive element and then remove the unknown voltage source and hook up a variable DC power supply. I...
