We are looking at our power options again.
We have a 20KW genset. Two 4k watt inverters, and six 8d batteries. We had been powering the inverters through the old fashioned 50amp plug, that we manually change over to shore power if available. We have only been able to pull that much power off of the genset, because that is all our cord can handle. The rest of the system is engineered to handle the 180 amps that the genset will put out. The cord/outlet setup that we have now is the weak link.
Now for the question. Does anybody have any ideas on how we can switch between genset power (180 amps) and shore power (50amps)? I doubt that we will ever need the 180 amps from the genset, but it is nice to have that capability.
Are we going to have to build our own switch?
Ideas?
Thanks,
God bless,
John
Why wouldn't a normal 200 amp transfer switch work? the use them in homes all the time, with generator backup systems. In your case you need to switch between 50 amp and potential 180 amp, a 200 amp switch should be perfect.
http://www.lowes.com/pd_330518-24212-RTSD200A3_4294857410_4294937087?productId=3200927 (http://www.lowes.com/pd_330518-24212-RTSD200A3_4294857410_4294937087?productId=3200927)
Pricy, but the same thing in Canada is close to $1200!!!
Brian
John,the big boys accomplish that through the inverters someway maybe time for a call to Don Rowe or Dick Wright
good luck
Umm, your 20kW generator should be putting out 80 amps, not 180. That's assuming it is set up the same way a 50-amp shore service is, which is to say 120/240-volt split phase. So the delta between the two is not that great.
One way to handle this is to put a generator sub-panel in, and hard-wire some of the load to that panel, so these items will only run when the generator is running. Then feed a conventional 50-amp transfer switch from one of the breakers on this sub-panel; that switch would then feed your main panel.
That said, 80-amp three-pole transfer switches are not uncommon. The guts of one of these switches is actually a reversing motor starter, and they come in all ratings. Our genny has a 70-amp main breaker and we use a switch like this.
-Sean
http://OurOdyssey.BlogSpot.com (http://ourodyssey.blogspot.com)
Sean did you use a Nema rated 3 switch?
Quote from: Zeroclearance on July 08, 2010, 02:56:26 PM
Sean did you use a Nema rated 3 switch?
I actually went with IEC contactors from Telemecanique, rather than NEMA units. The rating systems are similar but subtly different; IEC units are actually easier to size for non-motor loads.
Discussion of my transfer switch, complete with diagram, is here:
http://ourodyssey.us/bus-e-ats.html (http://ourodyssey.us/bus-e-ats.html)
Photo here:
http://odyssey.smugmug.com/Architecture/House-Systems/77568_m2Cuq#4277535_Gwb5R-L-LB (http://odyssey.smugmug.com/Architecture/House-Systems/77568_m2Cuq#4277535_Gwb5R-L-LB)
-Sean
http://OurOdyssey.BlogSpot.com (http://ourodyssey.blogspot.com)
looks like he divided by 110 instead of 240.
Thanks for the replies, gents.
We have our genset wired 120. So we basically have two 80amp circuits for a total of 160 (I originally said 180, my bad).
We will look at our inverters more closely to see if we can figure out how to use them in that fashion. Thanks for the idea, Clifford.
Sean, that switch that you mentioned is close to what we need. It would just need to be four pole in this case.
Brian, we have one of those switches in the garage. The problem is it doesn't switch the grounds, so it didn't work for us.
Thanks,
God bless,
John
Quote from: John316 on July 14, 2010, 05:30:23 PM
We have our genset wired 120. So we basically have two 80amp circuits for a total of 160 (I originally said 180, my bad).
Aaaaaaaah!!!
You need to change that right away.
With your genny set up that way, you're pulling 100 amps through the neutral of your shore cord. That neutral is designed for a max of 50 amps. You're lucky the cord has not melted or caused a fire yet.
Quote
Sean, that switch that you mentioned is close to what we need. It would just need to be four pole in this case.
Now I'm confused. Why would you need a four-pole switch?
Quote
The problem is it doesn't switch the grounds
Grounds should NEVER, EVER be switched. Grounds must be continuous at all times.
-Sean
http://OurOdyssey.BlogSpot.com (http://ourodyssey.blogspot.com)