We have used 3M Scotchkote Electrical Coating for years, mostly to coat vinyl tape at low voltage motor terminations and the like, to seal and prevent unravelling. Now the sale has been halted in about 10 states due to very high VOC content. Any suggestions for a similar coating product? I...
My coupling and alignment instructions for my diesel generator set call for #1 cylinder to be TDC and the generator rotor positioned with the north pole (@ the shaft key position) also TDC.
Why?
During a recent cleaning, we found some internal cabling that had insulation issues (see file). The cabling is from the load cables to the contactors (Cutler-Hammer), voltage level is 6.6 kV, the conactors are pretty much closed all the time so no frequent load spikes to speak of, and loading is...
Anybody out there use VCIs or VPIs (Vapor Phase Corrosion Inhibitors) in non-vented electrical enclosures to prevent corrosion? They are used widely when shipping, working by emitting a vapor that coats electronics. They are little round disks or some look like a plastic 9 volt battery. They are...
I have a speed problem with a hoist motor. In the down direction, it shifts to slow speed at the correct point, but when the platform reaches the stop proximity switch it has not fully decelerated, causing it to be going too fast when the brake sets and resulting in an over travel.
The...
I have never seen a generator that has water cooled windings, but I know they are out there.
I am wondering if the cooling medium (de-ionized water?) flows thru the hollow windings in direct contact with the copper winding or if there is a tube or coating inside the winding made of something...
Where can I find data on a particular thyristor. I want to make sure the fuse protecting it is the correct rating (Total I2t). The thyristor is N370SH16, but google searches don't come up with any data.
I don't have TCC for a high speed fuse, but I do have I^2t (A^2s) characteristics for Pre-Arc, and clearing @ 660 volts.
What is Pre-Arc? Will being close to this value at starting be detrimental to the fuse over time?
How should I treat the clearing value when at a lower voltage than the...
I use several Cutler-Hammer AMPGARD vacuum-break starters (7200 volt/400A) in a 2 high cubicle. What I find disturbing is the ground scheme. When the contactor is opened and load disconnected, the contatcor is then shut to short the load side and ground. But the ground bar only grounds to the...
I have a two speed, two winding fan motor, 460V, 100/25 HP. It is run as high and low speed, plus in reverse at low speed. It runs fine in low speed both directions, and can shift to high speed without issue.
When running at HS, the current increases over time, but not above name plate...
I have seen shore power facilities for cruise ships and they typically provide 4 or so cables at 6.6 or 11 kV, and a neutral cable. How is that neutral tied into the ships switchboards? Are they running 6.6 kV with a neutral bus?
I have discovered hundreds of instances where I have crimp lugs with a 3/8" bolt hole connected to another lug (motor leads) or breaker stabs, which have 5/16" bolt holes. All are silver plated copper, I am confident of tight connections, and thermal surveys have been very good. The hardware...
This is a sipboard installation. 480 V 3 phase ungrounded sub station feeding an elevator with a two speed two winding motor. When the motor is running I get ground indications on ground detector lights at the sub station, and they change the ground indication from phase to phase to phase. Sort...
I have a 480 v motor controller contactor mounted to a back panel, and the panel is mounted in an enclosure with 4 each 3/16 ss 316 bolts (140K PSI each). I know the available fault current is 30kA. How can I determine if the bolts can withstand the fault?
