Do modified-sine waves affect overcurrent protection?

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Re: Do modified-sine waves affect overcurrent protection?

George,
Parallel inverters are like parallel gensets, they have to be synchronized so that their individual sine waves do not overlap each other.
With inverters, they have to share a common reference or trigger signal.
Mark
 
Re: Do modified-sine waves affect overcurrent protection?

Mark, I don't believe out-of-sync inverters would cause a breaker to fail to trip when shorted from line-to-ground, would it?

I imagine the "43 amps" was taken from product specs of some sort, I don't believe the solar guy did any sort of real performance evaluation to some to that number.
 
Re: Do modified-sine waves affect overcurrent protection?

George, You didn't mention how long it took the inverters to shut down. It may be the inverter protection is reacting to the out-of-phase condition under load faster than the CB. Maybe you could amprobe the circuit to get a better picture of what is happening.
I found out a lot of high end inverter manufacturers (XANTRX,OutBack), offer systems to parallel their inverters.
Did you find the short on that stove ignitor circuit?
Mark
 
Re: Do modified-sine waves affect overcurrent protection?

Originally posted by mprairie:
George, You didn't mention how long it took the inverters to shut down.
I wasn't present for the big one. I only had my garage outlet experience mentioned in the first post of the thread, and I didn't hang in there long enough to knock the inverter down.

Before I continue, know that I'm not saying you're wrong and arguing: I'm trying to understand where you're coming from. :)

It may be the inverter protection is reacting to the out-of-phase condition under load faster than the CB.
Why would it care about an out-of-phase condition on a line-neutral (or ground) fault? Wouldn't normal 240V loads, or a line-to-line fault, bring out this beast?

Wouldn't I read less than twice the line-to-neutral voltage when I measure from line-to-line, if the inverters weren't sync'ed correctly?

Maybe you could amprobe the circuit to get a better picture of what is happening.
I was thinking that would be fruitless. But, with this predicament I'm having, it makes sense that I would get a meaningful reading with an ampclamp, since the entire process (of the breaker kicking) has been slowed so far down. ;)

Did you find the short on that stove ignitor circuit?
No, I diagnosed it over the phone and told them not to use the griddle, and to call the appliance supplier to repair it. The range was never in-place and malfunctioning while I was there.

BTW, the solar dude responded to my second e-mail today: "Huh, what? What first e-mail?" :roll:
 
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