Onan/Cummins 75kw quiet diesel connectors// source???

Topic: Onan/Cummins 75kw quiet diesel connectors// source??? (Read 961 times) previous topic - next topic

Onan/Cummins 75kw quiet diesel connectors// source???

August 20, 2019, 11:31:23 am

My generator quit earlier this month and i found two blown circuit breakers in the coach The genset still runs but produces no power. Upon pulling the panel, I noticed the hot leg of the two bakelite plugs coming off the inverter was burned completely in two. I cranked the genset and was got 118 volts between the burned lead and the neutral plug next to it. Nonetheless, thinking that there might be other wiring issues i decided to take the coach to our local cummins dealer . After a week, I was called today with a quote telling me the inverter was bad and it would cost around $4000 to fix it. When i questioned how i could get 118 ac volts with a bad inverter, the tech got on the line and admitted that they did not replace plugs but had to replace the entire inverter.
Since i paid nearly this amount to the same shop to replace a bad stator and rotor less than two years age. i'm looking at 90% of the cost of a new unit. Told him I'd pick it up and fix myself. I'm beyond frustrated that this is the diagnostic mindset.

My question is: does anyone have a source for the plugs used on a cummins inverter? I just don't want to sink thousands of dollars in a unit if the problem is simply a burned plug.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #1 – August 20, 2019, 11:58:51 am

Someone else will answer but which inverter are you talking about?,which generator do you have?I just replaced my charger/
inverter with a Magnum pure sine wave and the parts were about $1700,I may be wrong but don't think there is a "Cummins"
inverter out there,get back to the forum,more help on the way.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #2 – August 20, 2019, 12:18:51 pm

Cummins Onan Commercial QD 7.5 Diesel 120V | 7.5HDKAT-41934 - Norwall...
If it is a 7.5 Quiet Diesel, very likely has a inverter as it is variable speed, but doubt it was OEM in 91.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #3 – August 20, 2019, 08:44:34 pm

Rich pilot has to tell us what exactly he has,then we can go from there.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #4 – August 20, 2019, 09:20:45 pm

Quote from: John44 – August 20, 2019, 08:44:34 pm

Rich pilot has to tell us what exactly he has,then we can go from there.

His title, "Onan/Cummins 75kw quiet diesel connectors// source???"
Obviously 75 kw a typo, but quiet diesel and inverter problem certainly points to a 7.5 Onan/Cummins Quiet Diesel. Believe Foretravel used the quiet diesels in several later models, and of course were used in many SOB's.
Quiet Diesels were similar in operation to the Honda eu2000. Voltage and cycles stayed the same because of the inverter, but engine speed would increase when load increased.
Think Brad had one in his coach combined with the hybrid system.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #5 – August 21, 2019, 09:28:19 am

Quote from: Richrpilot – August 20, 2019, 11:31:23 am

I'm beyond frustrated that this is the diagnostic mindset.

My question is: does anyone have a source for the plugs used on a cummins inverter? I just don't want to sink thousands of dollars in a unit if the problem is simply a burned plug.

We live in a time when the labor usually costs far more than the parts. I think you mean socket. The configuration of the socket is determined by the intended voltage and current. So 120VAC, how many amps? Once we know that then we can go to the manufacturers for a name and part number followed by a trip to eBay or Amazon to source the parts, or if you wish a dealer.
I imagine right now you living with a giant brain cramp with "$4,000 not again" running around in circles.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #6 – August 21, 2019, 10:51:54 am

Looks like Cummins likes to keep their repairs and parts in house, not much info out there but this might help a bit.
Onan Quiet Diesel 7.5kw Controller/Inverter Trouble - SmokStak

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #7 – August 21, 2019, 03:10:48 pm

Not familiar with this model but on my Powertech 10Kw one of the things I did was to remove the plug inside the control box and connect the wires directly. May not be relevant to your case but the point is that the plug may not be necessary and could possibly be eliminated? I would certainly look closer at this possibility before spending that kind of money.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #8 – August 24, 2019, 10:36:15 pm

Thanks to all. I did not realize i was getting replies. My geneset is indeed a quiet diesel 7.5 kw hdkaj-1145H. Its an aftermarket addition snce it was made in 2004. There is a dual plug/socket labeled "1" and "2" on the inverter which have ring terminals that attach with tori screws. One is ground and the other hot. The hot wire melted and burned in two at the connection.I know i had a short in the built in vacuum shortly before the generator quit producing power(breaker was tripped). It continues to run perfectly, but produces no power but i was able to read 120v between the burned off wire and ground. I will try to post a picture of the wire that is burned.

I removed the genes from the coach today, and intend to pull the inverter and crack the case to see if I can spot other burned wires anything that looks burned on the circuit board that is supposed to be inside the inverter/controller. If there are none, I'm considering reconnecting the burned wire and restarting the genest. Advice?

sorry. I can't seem to figure out posting pictures

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #9 – August 24, 2019, 11:18:39 pm

Picture

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #10 – August 24, 2019, 11:24:45 pm

Obviously my initial post looking for a
Connector was in error. The burned wire terminated in a ring terminal that screws into a brass
Post with a torx screw. The plastic insulator between the two posts was partially melted. I had erroneously thought there was a plug/socket arrangement.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #11 – August 24, 2019, 11:27:17 pm

Get it open and if no fried boards see if the wire that goes to the terminal can have the insulation stripped back. Find a copper tubing union, probably 3/8" use it as a connector and solder both ends to it. Then wrap insulated tape and see if it works.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #12 – August 25, 2019, 06:26:10 am

Quote from: Richrpilot – August 24, 2019, 10:36:15 pm

It continues to run perfectly, but produces no power but i was able to read 120v between the burned off wire and ground.

Rich,

1.Where did you measure the generator out put?
2. Are those wires the feed from your generator to the coach transfer switch?
3. You must have the coach plugged into shore power if you are sure that your generator is not producing power.
4. If #2 & 3 is yes then you need to look at your transfer switch. Because it should be separating shore from generator. If the transfer switch has a failure and back feeds into this wire you can have the results you are seeing.
5. If #3 is no then the generator is producing power.

You need to do some more research into the failure before you try to just reconnect those wires. It could be that you just have a bad connection that got hot and melted BUT you need to make sure that you don't have a bigger problem.

Mike

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #13 – August 25, 2019, 09:21:25 am

Quote from: Richrpilot – August 24, 2019, 10:36:15 pm

If there are none, I'm considering reconnecting the burned wire and restarting the genest. Advice?

sorry. I can't seem to figure out posting pictures

Last things first because "this thread is useless without pictures."
Click "Preview" then scroll down and follow the directions.

Use a dummy load of some sort to test your generator before you hook it back up to the house. Anything from an electric heater to a resistive light bulb. Then measure the AC voltage.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #14 – August 25, 2019, 01:52:37 pm

I attach a schematic of the controller/inverter. The burned contact was at block tb3 labeled "1". It is the main generator ac output just before it splits into two hot legs into the double pole circuit breaker. It is at the lower right hand corner of the schematic. The breaker did not trip which i assume is because the bad connection was upstream of the breaker? I am hopeful that since i can still obtain 120 volts between the burned wire that connected to "1" and the ground post at "2" (with shore power disconnected) that the only issue i had was a bad,high resistance connection which burned up.
But as is no doubt obvious, i know very little about electrical issues. Should other components be suspect or does the fact that i get 120 volts at tb3 suggest no other damage?

Thanks for all your help.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #15 – August 25, 2019, 05:39:20 pm

I doubt that the inverter controller is bad. It looks like it had a loose connection. Loose wires cause fires. You just have to figure how to get the wiring reconnected and you should be fine. I have replaced inverters and rotors when the magnets come off the rotor.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #16 – August 25, 2019, 11:02:57 pm

Thanks. I had to replace rotor and static on this one year before last when magnets tore loose. They did not replace inverter then and it had run fine since

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #17 – August 26, 2019, 10:19:43 am

Quote from: Richrpilot – August 25, 2019, 01:52:37 pm

I am hopeful that since i can still obtain 120 volts between the burned wire that connected to "1" and the ground post at "2" (with shore power disconnected) that the only issue i had was a bad,high resistance connection which burned up.
But as is no doubt obvious, i know very little about electrical issues. Should other components be suspect or does the fact that i get 120 volts at tb3 suggest no other damage?

Thanks for all your help.

I would say a high resistance connection and it burned everything up. Fix the burned up mess and I would think you would be good to go.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #18 – August 26, 2019, 04:46:34 pm

UPDATE: here is the culprit; a 75 cent connector that melted because one of the connections was faulty or loose. Problem is Cummins doesn't sell parts to the inverter controller. Sell it only as a unit ~$1750 per copy. I will fabricate something out of the remains of this piece unless one of you has an old Onan inverter I could scavenge this piece from.

. The quote from Cummins ship to remove the genset and replace the inverter was north of $4200. Their diagnosis of faulty inverter was expensive enough. I won't be back there again.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #19 – August 26, 2019, 06:07:00 pm

What is the wire size?

There are connectors that are called Polaris taps.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #20 – August 26, 2019, 06:29:59 pm

How about a pair of these? 800 +amps

Polaris 500 MCM - 4 AWG Bagged Insulated In-Line Splice, Black-ISR-500B -...

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #21 – August 27, 2019, 10:58:46 am

Personally, I'd find a bulkhead fitting/strain relief that will work with your cable and use a couple of split bolt connectors, properly sized, to reconnect. Insulate them using friction and electrical tape and you'll never have a problem again.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #22 – August 30, 2019, 06:20:23 pm

Thanks to this forum for all your help and encouragement. Generator running and powering Boothe air conditioners for the price of two split bolt connectors and some tape. $4200 unnecessary controller inverter replacement avoided.

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #23 – August 30, 2019, 08:03:14 pm

As a guy who owned an Ace Hardware store for 15 years the split bolt connectors are simply not used enough. Everyone wants to go plastic and squeeze lock but sometimes the simple mechanical solutions work best. With the cure you have chosen i can assure you you will not be revisiting this problem any time soon. And with the savings of a couple coach bucks you can afford another adventure! Nicely done!

Re: Onan/Cummins 75kw quiet diesel connectors// source???

Reply #24 – August 31, 2019, 09:51:38 am

Quote from: Richrpilot – August 30, 2019, 06:20:23 pm

Thanks to this forum for all your help and encouragement. Generator running and powering Boothe air conditioners for the price of two split bolt connectors and some tape. $4200 unnecessary controller inverter replacement avoided.

Most of this isn't rocket science. Just a decision on where you want to spend your time or money.

Congratulations on a job well done.

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