Search results for query: *

Thanks both, Unfortunately the multi-function relay in question doesn't include LOE protection and it'd be hard to justify the economics of adding it on a machine this size, especially given the likelihood, as far as I can tell, of an event tripping one of the other protections (excessive kVAr...

For a 600 kVA, low-voltage grid-connected brushless synchronous generator, can loss-of-excitation be picked up reliably enough via a combination of under/over voltage and Q import limits? My understanding is that a sudden loss of excitation (AVR fault, open-circuit field winding, etc) would...

To update on where things got to, a large load bank was hooked up and used to sink current from the grid, and separately, current from the isolated generator. The generator test showed textbook waveforms, and the grid test showed minimal imbalance of 2-3%. So the issue is only apparent when...

Thanks Bill, very helpful! In this case the main feed will already be 3-ph + N, and neutral is solidly earthed, so it sounds like that's ok. However, nothing has been purchased yet, so are there any other advantages/disadvantages in picking 277/120 over 480/120? If the latter is more common...

I'm not at all familiar with UL/NEC requirements for switchboards, so please help with recommendations for protection of a single-phase 5 kVA control transformer. It's a 277/120 V unit, tapping off 1 phase of a 480 V system and supplying non-motor loads of about 25 A continuous plus around 30 A...

Inconclusive testing from the phase rolling... fault looked much different to original (significantly more harmonics and varying phase-angle shifting of current waveforms that make me suspect something inadvertently altered on site - unfortunately I'm only able to be involved remotely). To try...

stevenal, that was indeed considered but have confirmed our measurements with a separate power quality meter and current clamps. VTer, very low loading, 10-15 A/phase. At that level (i.e. when not generating) currents are balanced within a couple of A. Bill, thank you, after submitting my...

I have a 3-ph synchronous generator, 500 kW 415 V, feeding directly onto a (weak) grid through a standard 800 kVA, 415/11 kV distribution transformer (Delta HV, solidly grounded Star LV) via a contactor and circuit breaker. The system is new and from first synchronisation, current on phase L1...

I've asked this question regarding wind turbine applications in the energy conversion forum (thread 338315), but I imagine it equally applies to antennae and other tall structures with electrics up-tower, so will check here too. Is anyone familiar with the requirements for (or have experience...

Is anyone familiar with the requirements for (or have experience with) earthing system testing of large wind turbines or other tower structures (particularly in the UK but I'm interested in other international input too)? Specifically, what sort of testing is required to verify the earthing...

It's structural bar, 20 mm dia, bent rods tied together.

Thanks gents, I do have an Al gland plate on the switchboard and use brass or PVC glands. Was a bit surprised by the generator manufacturer's response considering we'd be paying for the special gland plate anyway... their rationale was that the current was too low to cause any significant...

Greetings, I'm looking at cable ducting arrangements for a 415 V, 600 kVA generator where the single core power cables feed out through a concrete foundation slab in which the rebar is bonded to the earthing network. Cables are single-core and connected 2 per phase (carrying around 400 A...

I have a note from a supplier about a CT supplied with a generator AVR that its ratio is 130:1 and its "useful current range" is 325-650 A. What is meant by this in terms of the 0-325 A range? Is the response non-linear in that region so it loses accuracy, or am I missing something? Thanks, EK