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Very Dangerous Generator/Electrical Problem
Last night here at the Pelican Lake Motorcoach Resort we had a VERY DANGEROUS, POTENTIALLY FATAL, incident and I’m looking at what to do in checking the system and correcting the problem. Also, everyone needs to know that this can happen and how to make sure that if there is a problem how the would they be aware of it.
We had a power failure in a part of the community that was the result of a transformer failure. The failure occurred at about 7:30pm and was estimated by Florida Power and Light to be restored by about 9:30pm.
Several of us were sitting around with battery powered lights having a beer and talking while we waited for the problem to be corrected. The owner of the 1999 XL Liberty Coach decided at about 9:00pm that he would go to bed and went inside the coach. Immediately he started the generator and just as he did the lights came back on. One of us knocked on the door to tell him that the power was back on, and that he could shut his generator down. When he did, the lights went off. He, thinking that the issue wasn’t yet resolved restarted the generator. When he did the lights came back on. My first thought was that he somehow had his lot lights powered by the generator. I went out to the street to see if the power was back on and discovered that all of the lights in the effected part of the park were on. I immediately thought of the possibility of the generator back feeding though the power cord and had one of the guys to go to the power pedistal and switch off the main circuit breakers. When he did, the lights up and down the street went off. My thought then was of concern, more like panic, that the power company people were in danger of working on power lines that they thought were off but were now powered from the bus generator. I went to where they were I found that they were all on the ground waiting for the new transformer to get there. You can’t imagine the relief that I felt, and that they felt, when I found that no one was hurt or worse, maybe dead.
I know nothing about the electrical system on a Liberty, but there has to be a transfer relay or a reverse current relay in the system that has failed. My question is, where and what is it? As it stands now, with the power cord not connected and the generator running, the blades on the power cord plug are hot with full power from the generator. i wonder now what would be the result if the power cord were to be plugged in to a hot receptacle. I would hope a popped circuit breaker.
ANY HELP WOULD BE GREATLY APPRECIATED
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5 Replies
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I am not an expert, but Liberty uses a 2 contact transfer switch. The contacts are essentially heavy duty relays. The system is set to have the contacts open when no power from shore or the generator is available. The coach is getting its power through the inverters.
If shore power is connected to the coach the appropriate contact closes allowing shore power to enter the coach. Until shore power is energized at the pole the contact is open so no power in the coach can back feed. If power (inverter or generator) could back feed and a person could risk electrical shock from the prongs on the shore power cord receptacle on the coach or on the shore power cord.
When generator power is available within the transfer switch is a provision to open the shore power contact to prevent just the sort of incident described.
That coach should be checked to insure the transfer switch is operating as intended because it sounds like something has failed and the shore power contacts remain closed while the generator is running.
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Shore cord should not at anytime be getting power from generator. Sounds like as Jon mentioned the contractor has failed. This could also cause issue running gen going down the road with cord in as the power cord end could contact the coach body as this is a small area with cord in. Needs checked out asap
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Thanks for the input. I’m onboard with all said and am aware of all the ramifications.
I can’t think of a more dangerous situation. I think that aside the possibility of electrocuting someone there is a serious possibility of fire.
My thought right now is that for some reason the subject relay may have failed with the contacts closed.
I’ll keep you advised.
JC
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At this point, I have advised him to switch the shore power breaker off and do not under any circumstances start the generator until we can get it sorted out.
JC
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Wow John that is scary, a (ATS) automatic transfer switch has the 2 big relays in them, Sounds like 1 of the relays is in the frozen on position.
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