Electrical (gen-set) question

I thought that it was a special cable, that commanded inverters to work in sync.

Use two lamps, one "lamp on" (in a green globe), the other "lamp out" (and in a red globe)?

Joe Gwinn

Regarding a danger of backfeeding a generator, I have a question.

What if the generator has a circuit breaker? So the backfeeding power goes in through a breaker? Would the breaker save the generator from backfeeding damage, in this instance? (assuming properly sized breaker)

thanks

That brings back memories. In the airforce at a radar site we had 3 big Buda (sp?) geneators which when used to operate the set had to be synched. There was the same light bulb on the control pannel and when it went out the switch was thrown to connect the second one. Ah yes 1952 boy was that a long time ago. ...lew...

I think anyone who would mistake the "burn out" of a lamp for the way the lamp responds to the phase matching of the generators should not be in the position of being alowed to do it. :-) ...lew...

Joe there is a saying something about making it Idiot proof and what happens along comes a biger Idiot. :-) ...lew...

Nope, just direct connection to the inverter output. Strictly an electrical safety issue.

Regarding Brian's article, there's no date so we don't know the vintage of the electrical equipment. Circuit breakers, especially in the old days, depended on a minimal amount of resistance and inductance between them and the source. They are also limited as to the absolute maximum surge current.

I can't think of a worse situation than strapping together the two busbars of generators exactly

Never seen a "bright light" system. Every power plant I have ever been in, that had idiot lights, had lights that were out when in sync. All but a couple also had synchroscopes. jk

Yes , no and perhaps.

A breaker can not (by itself) sense that the power flow is reverse. So if the reverse flow isn't large, then NO.

If the flow is large, so that the current exceeds breaker rating, then perhaps. If the flow is large, then yes. If even larger, then again perhaps not.

TYpical rule of thumb in protection for piston (Turbines are a different animal) engines (large) against reverse power, is 15%-25% of rating, for a time period from seconds to minutes. But that requires a reverse power relay.

Still won't protect you against twisting or snapping your shaft.

jk

I can, and thats closing in one generator to a stiff system, 180 out. You still produce a fault 2x that of the 3phse bolted fault, but that starts out as a larger number in the stiff system case. jk

On all the multi generator sets I have seen the generator connects to a circuit breaker and then to the bus. The circuit breaker is what you turn on when the frequencies are in phase.

Bruce in Bangkok (brucepaigeATgmailDOTcom)

It would depend on the sub-synchronous reactance of the alternator, not the synchronous reactance. The fault current would be no larger than that which occurred with a pole-slip and a normal generator will survive that. The operators, might need to do some laundry before appearing in public, but the alternator should suffer no major damage.

Mark Rand RTFM