Voltage, frequency, protection control.

[WGB]

I would like to drop the load off of my ST or VOLTmaster head in the events of start up and shut down, or other problems.
I asked this question over on the X brand board some time ago.
This is one solution:
http://www.time-mark.com/products.php?id=46&category=Voltage%20Monitors
And:
http://www.time-mark.com/products.php?id=49

I would use the two in series, with other controls to pull in or drop out a contactor.

Bob, Bruce, Veggie, or others would just build from scratch, I'm not that handy, but would be open to suggestions.

[BruceM]

WGB,
I think using one of the commercial over/under voltage units, at least, is smart, and can save you a lot $$$ grief if you do things like run a submersible pump or other motors where replacement cost can be painful.

This over/under voltage unit you found has a fixed 0.5 second delay- not long enough for a Listeroid taking a surge load.

The frequency monitor  has only a 1 second fixed delay.  

Both would be a big disappointment on a low speed Listeroid, causing nuisance trips on surge loads and perhaps not useful on most smaller wattage generator sets.

Bill Rogers once recommended a very nice over/under voltage unit with adjustable delays.  I think it was the Magnecraft 831, which has delays up to 10 seconds.

http://www.alliedelec.com/Search/SearchResults.aspx?Ntt=831&Ntk=Primary&sid=125D6432B21B&i=9&Pst=Magnecraft+&N=0&sw=y

My non-PCB, "full house" AVR has adjustable delay and adjustable over/under voltage trips built in;  I do think adding a unit like the one Bill found is wise, as the Listeroid will slow down and not trip the breaker with an overload or  if something like an electric glue gun fails as a near short.

Frequency monitoring makes more sense if you have an AVR, as it would try to keep voltage up even though rpm is too low.   My Lister-Picaxe engine monitor does a shut down for low engine rpm (with delay), and this solves the low frequency problem for me.  Someday I might add power frequency monitoring. It would catch a slipping belt, though I see that first now as a  low voltage cutout trying start motor loads, so I'm not highly motivated.

Best Wishes,
Bruce

[WGB]

Thanks Bruce,
  That looks good, I got sticker shock on the two I listed $330.00 plus freight.

[BruceM]

Glad to be of help, but the thanks belong to Bill Rogers for finding and testing the Magnecraft 831.

Alliedelect.com is a good source for some electronics-  I found some real bargains there on din rail mounted relay sockets and sealed 240VAC relays, for my AC charger.  They only carry top brands, also.