To ground or not to ground a 2500 KVA, 480 volts diesel-generator
To ground or not to ground a 2500 KVA, 480 volts diesel-generator
(OP)
Criterion that should be taken into account to decide what grounding method are to be used.
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To ground or not to ground a 2500 KVA, 480 volts diesel-generator
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RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
It is my understanding that it is much more common (now a day) to find industrial facilities with low resistance 4 wire system for better ground fault detection and isolation.
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RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
Bill
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"Why not the best?"
Jimmy Carter
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
One more question: If this generator were high-resistance grounded, ¿would it be prone to suffer overvoltage conditions?
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
High resistance grounded systems will see somewhat more overvoltage conditions than a solidly-grounded system, that is one of the trade-offs. But the overvoltage can be controlled, unlike ungrounded systems.
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
You mentioned an important point: "But the overvoltage can be controlled". ¿May I ask you how?
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
Pound a stake in the dirt when the generator is running? Or just make sure I'm using a grounded 3-wire connection between load and the portable generator?
What about a light-cart/generator on rubber wheels at the job site? That's a larger, commercial generator-light rig. Do I assume the rental company has it properly grounded for 440 vac/120 vac loads out on the jobsite?
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
Yes, but that's not enough.
My 1.6kW/115/60 generator on rubber pads has a ground terminal on the frame, and came with manual verbiage and a bunch of yellow stickers, all stating unequivocally that the frame should be wired to a metal ground stake or a water pipe in the ground before even starting the engine. I store a roll of ~#10 ga wire with the generator for just that purpose.
That is the only system ground when the loads are connected by extension cords.
Mike Halloran
Pembroke Pines, FL, USA
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
In British terminology, you're confusing the earth continuity conductor with the connection to the mass of earth. If you connect the metal cases together without a connection to the mass of earth then you only succeed in making them equipotential, but they are not earthed.
Substitute 'ground' for 'earth' as necessary!
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
RE: To ground or not to ground a 2500 KVA, 480 volts diesel-generator
In a 4-wire system you have to decide if all your ATSs are 3-pole (solid neutral) or 4-pole (switched neutral), and make sure that any future changes to the system keep that same design philosophy. Next major upgrade to the facility someone will select the wrong kind of switch though, and cause circulating ground currents and potentially trip ground fault protection.