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Author Topic: Transfer Switch  (Read 1733 times)
Sam 4106
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« Reply #15 on: March 27, 2013, 02:59:49 AM »

Justin,

It sounds like Glen's generator is already set up to put out only 120V, since you had "nothing on across L1/L2". If his generator is 120V only, and it has a single neutral, then all the current from both legs of the 120V are returning on the single neutral. And, if there is a combined 50A load, the neutral is carrying all 50 amps. If the installer didn't use a wire capable of carrying 50 amps then that is why the neutral burned up. Please tell me the full name  and model of the generator, and the KW rating. If the generator is 120V only output then no load balancing  is required. BUT, if it has 240V output, DO NOT put a jumper wire between the legs. That will cause a dead short.

Andy,

"This unit has 2 legs at 120V." That, and presence of the jumper, tells me that your generator is not putting out 240V. It takes more than removing a jumper to change a generator from 120V to 240V output. Have you checked the voltage between L1 and L2? If you have no reading  between L1 and L2, your generator is not producing 240V. If your generator was putting out 240V, adding a jumper will cause a dead short. If you are lucky, you will trip a breaker before you do any damage. I had an Onan 7.5 KW Quiet Diesel generator, with inverter technology, that had 2 legs of 120V, but it would not put out 240V.

I need more information.

Good luck, Sam

 
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1976 MCI-8TA with 8V92 DDEC II and Allison HT740
justin25taylor
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« Reply #16 on: March 27, 2013, 06:41:53 AM »

Sam,
The generator is setup to put out 240 volts. Those loads need to be balanced. When I said I got nothing across the 2 legs, it was before I found the burned wiring in box.
Yes, I know in a 240 system you cannot tie L-1 and L-2 together. Doing so will let the smoke out Wink

I have seen the 2 legs tied together after the main breaker in a 120v only system.

His generator's brand name escapes me, but it is almost exactly like a 15kw Powertech. I'll be at the bus later and will get you info if you would like it.

As always, thanks for the help!

Best,
Justin
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AndyG
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« Reply #17 on: March 27, 2013, 07:47:09 PM »

Andy,

"This unit has 2 legs at 120V." That, and presence of the jumper, tells me that your generator is not putting out 240V. It takes more than removing a jumper to change a generator from 120V to 240V output. Have you checked the voltage between L1 and L2? If you have no reading  between L1 and L2, your generator is not producing 240V. If your generator was putting out 240V, adding a jumper will cause a dead short. If you are lucky, you will trip a breaker before you do any damage. I had an Onan 7.5 KW Quiet Diesel generator, with inverter technology, that had 2 legs of 120V, but it would not put out 240V.

I need more information.

Good luck, Sam
Good catch Sam.  I was wrong about the jumper wire.  I could swear that I got this idea from the manufacturer but maybe not.  I did thas about a year ago.  I did put my meter on the leads and found 120v to neutral on both sides and 0 between them just like you said.  I'm beginning to think that I can't get 240V from this unit which is a real disappointment.  I need 240V to run the pump on my water well.  I have a Power Tech AKA PTS genset in my rig made in 2000.  Model CD7000, volts 120.  Class F......  I have done a little Googleing and see the name plate on similar units is marked 120V/240V.  Looks like I'm out of luck on the 240V part. 
I also checked inside of the transfer switch to make sure that all of the wires were secure.  The switch is a Magnetek Model ATS, 50A, 240VAC.  I did start the generator up while I had it open and saw the switch energize to send voltage into the coach.  I also saw the button which needs to be pushed in if it fails to work in the future.
Thanks
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Oonrahnjay
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« Reply #18 on: March 28, 2013, 09:35:13 AM »

Good catch Sam.  I was wrong about the jumper wire.  I could swear that I got this idea from the manufacturer but maybe not.  I did thas about a year ago.  I did put my meter on the leads and found 120v to neutral on both sides and 0 between them just like you said.  I'm beginning to think that I can't get 240V from this unit which is a real disappointment.  I need 240V to run the pump on my water well. 

     Andy, I'm not one of the electrical experts here but it looks to me like you have the basics of 240V.  I don't know if it's practical to actually get 240 out of the wiring and regulator controls, etc. on your bus but I would look into this further.

BH  NC   USA
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
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