I have a few NEC code questions that I have not been able to have answered to my satisfaction yet, and I am hoping some of you code experts can help me out.
Background:
My company routinely uses #4/0 AWG single-conductor type-W cables and smaller (#6, #4, #2 AWG) multi-conductor type-SOW...
Guys & Gals,
We have a 2000 HP, 292 RPM (24-pole induction), 4160V, 60Hz circulator motor on a test stand. It's an Allis Chalmers motor and is probably 30-40 years old.
I am trying to figure out some ballpark numbers for the no-load current and the rotor moment of inertia. Do any of you have...
Our local natural gas utility company has recently installed a metering station and a pipe 4" in diameter and the pressure regulator is set to 5psig. We are supposed to hook up a flexible pipe from the utility pipe to our natural gas generator. My gut says this meets the NEC definition of...
We are using #4/0 AWG dual rated "type-W/RHH" flexible power cable on a job. The manufacturer's data sheet lists the cable as rated 405A @ 90C based on NEC table 400.5. We will be terminating the cable to a power terminal block rated 75C. The cable is going to be installed in an uncovered...
What is the proper voltage to test High-side to ground for an insulation resistance test on a set of 4200-120V potential transformers? Specifically, a "maintenance" test as this is older used equipment. I have the NETA MTS table that says for "electrical apparatus" up to 5000V, the MEGGER test...
Hello all,
This is a hypothetical situation:
I have three #4/0AWG type-W 90C copper single-conductors installed an uncovered cable tray per 392.10. Cables are terminated to a transformer at one end and a breaker with 75C lugs on the other end. Ambient temperature worst case is 40C.
The base...
Hello all,
I have a 2500kVA, 60Hz, 5.75%Z, 480V-wye to 7200V-delta transformer. I will be using a couple of 440V, 50Hz gensets to start and run a customers 6600V, 50Hz, 650HP motor.
I am aware that typically a 60Hz-rated transformer can be derated for 50Hz service by derating the voltage to...
I will have 12 480V generators in parallel with KW and KVAR load sharing connected to a 4160V bus through a bunch of 2500kVA transformers. I am attempting to run a Dynamic motor start study with one 5000HP motor running and one 5000HP motor starting on the 4160V bus. The 5000HP motors are...
I have this situation:
panelboard-bkr1
|
cable
|
|
bkr2
|
contactor
|
overload relay
|
motor
bkr2 is a magnetic-only MCP. (100A continuous, 150A frame)
motor is a 25hp induction machine (31A full load, 480V)
bkr2, contactor, and overload relay form a packaged stand-alone motor starter
I know...
