Excellent. That is basically what I originally told them to do but then started having second thoughts after noting the dwg did not show that T10, T11 and T12 (overload points 1, 2 and 3) were tied together.
Man is troubled by what might be called the Dog Wish, a strange and involved...
Wow - thanks for all the great responses. We didn't really need physical connection directions. We always use lugs, mechanical fasteners, void fill material, and usually design a raychem cover.
The rest of the story is we have to remove the overload protector (its testing does not meet our...
Please help me understand how to wire this 3P, 460V motor that has internal automatic thermal protection. Tracing out what I have been been provided seems to lead to 3 open phases. What does the dwg mean (top upper left) "insulate separately" and what do i do with those three wires? Where is...
I have 4kV vertical motor. From Feb 6, 2019 until "the event" on April 9, 2019, the UMB (spherical roller thrust type) indicated high temperature spikes on numerous occasions. The spikes (+300F) were detected via remote indications and most lasted less than 30 minutes. On April 6, 2019 the...
My huge apologies. We were not doing insulation resistance testing (megger testing). We were doing DRLO testing using a megger branded instrument. I should have been more careful with my words. So reading back over everyone's responses who correctly assumed that I meant ductor testing, it...
Thanks. My technicians said it was a CT. By removing the CT the meg reading dropped by 70-80 micro-ohms. Maybe they were supposed to take it out of the circuit to start with and just did not know. Most of the runs in this switchgear do not have CTs where we are measuring. This one...
When conducting a megger test of 4160V switchgear bus (cubicle to cubicle), how much resistance would a CT add to my result?
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
Big Thanks! Management will not shut motor down now and let me repeat measurements. So all of this advice now will just make me smarter for next time.
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
The motor was 200HP, 1.15 SF, and 235 FLA. Some readings were taken at the motor leads and some readings were taken at the field leads in the breaker cabinet after the motor was reconnected. All readings were between 5 and 8 percent imbalance. I believe the readings were taken with a meter...
I have a 480v 3 phase induction motor with 5 to 8% phase to phase resistive imbalance. Mangegemnf decided to start the motor without further troubleshooting. Current imbalance is low around 3%. What effects would I see with a resistive imbalance of say 5 to 10%? Should I push for more...
The rest of the story - yes it is a T frame, design B motor. These motors have a damper system but it is not air tight and back spinning does occur. This motor is fed from a molded case thermal magnetic breaker and thermal overload relay (this is a standard design we use because the thermal...
I have a 460V 75HP fan motor (85.9 FLA and 684 LRA) that tripped its feeder breaker on startup. Everything has checked out good. It is possible that this fan was freewheeling backwards when we tried to start its motor. About how many amps could that situation draw? Or is there a calculation -...
jraef,
what I meant was that 24 to 209 is acceptable. Anything outside of that is unacceptable and requires further investigation. Could be a test method problem or could be a component issue.
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as...
24 to 209 seconds from my Freedom C306 Class 20 trip curve.
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
I am conducting periodic testing (5 year frequency) to verify that the relay will trip within the time specified on its characteristic curve. I test at 300% of the current setting for example. The curve does not state whether or not it was developed for a single pole.
Man is troubled by what...
I am testing Cutler Hammer C306 bi-metallic TOLs. Should the poles be tested individually or in series?
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
I have an ungrounded 125VDC diesel generator start system that indicates a positive ground via (1) ground detection light illumination on the battery charger and (2)voltage to ground measurement. (+) to grd reads 75.4VDC while (-) to grd reads 56.7VDC.
The criticality of this level of grd on...
