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Can someone explain isolated ground?
- Thread starter cjkeeliii
- Start date
rmgill
Active member
I can't explain with the CUCV. But in General. Isolated ground is where you have two ground paths for a system to avoid adding RF noise to something.
In my case of a building electrical infrastructure in a computer room. The wiring going to the electrical outlets is an isolated ground setup. There's a grounding conductor that's insulated that connects JUST the outlet and runs directly back to the grounding bus bar on the Power panel or Smart PDU/Stepdown Transformer. There is an additional grounding path through the conduit, thats attached to the floor, the other grounding paths to other conduit, water pipes and the floor grid through the data center and the large wire gauge grid which is interconnecting all of the floor grid risers.
What this does is allow for a safe current return path for the outlet itself which is not as likely to pick up the masses of RF noise and transfer that to the computers and cause issues. The larger grounding grid and ground path through the conduits themselves is there for the safety of the system and to bleed off excess electrical current.
Hopefully this helps.
In my case of a building electrical infrastructure in a computer room. The wiring going to the electrical outlets is an isolated ground setup. There's a grounding conductor that's insulated that connects JUST the outlet and runs directly back to the grounding bus bar on the Power panel or Smart PDU/Stepdown Transformer. There is an additional grounding path through the conduit, thats attached to the floor, the other grounding paths to other conduit, water pipes and the floor grid through the data center and the large wire gauge grid which is interconnecting all of the floor grid risers.
What this does is allow for a safe current return path for the outlet itself which is not as likely to pick up the masses of RF noise and transfer that to the computers and cause issues. The larger grounding grid and ground path through the conduits themselves is there for the safety of the system and to bleed off excess electrical current.
Hopefully this helps.
Bunkerbuilder
New member
Actually they both have isolated grounds.
Its the way GM engineers figured out how to charge 2 12 volt batteries.
Are you are aware that the only part on the CUCV that is 24V is the starter?
This may be a valuable resource to you.
http://www.tpub.com/content/trucks1.25ton/TM-9-2320-289-34/index.htm
Its the way GM engineers figured out how to charge 2 12 volt batteries.
Are you are aware that the only part on the CUCV that is 24V is the starter?
This may be a valuable resource to you.
http://www.tpub.com/content/trucks1.25ton/TM-9-2320-289-34/index.htm
SPECIALTYLC
Member
It means that the ground connection is insolated from the alternator case. The first alt output or positive is connected to the 2nd alt ground post. The first alt can be a normal case grounded alt.
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Crash_AF
Active member
The theory of operation of the CUCV system requires that the ground for the passenger's side alt be isolated from the rest of the CUCV's electrical system because it is charging the battery on the 24V side of the system. The reason is because the 24V side is isolated from the vehicle chassis electrical system so that the rest of the vehicle can be 12V. If the passenger's side alt is grounded to the vehicle block, the 12V system gets 24V and blows fusible links and usually the alt as well.
The driver's side alt is not required to be isolated ground, but it is so that the supply system only had to stock one alternator for the truck instead of two.
Later,
Joe
The driver's side alt is not required to be isolated ground, but it is so that the supply system only had to stock one alternator for the truck instead of two.
Later,
Joe
As much as people complain about this system, I really think its ingenious. I love it!
Dodgeman1941
New member
The way I explain it to people who are trying to understand how it works is; The first alt {drivers side} takes the ground in and bumps it up to 12v and drops that into the first bat. The second alt {pas alt} takes the 12v in through the "ground terminal" and adds another 12v on top of that for an output of 24v and puts that into the second bat. The alternators are different {isolated ground} from standard alternators being that the input "ground" terminal has an insulated sleeve and washers so that the case is not grounded. If the case is grounded, the high alt {pass} would create a dead short in the 12 v system. I know this by accident when the pass side ground terminal accidently bridged the post to the case, big sparks. You can use a standard grounded input alt on the drivers side in a pinch because that one has the input terminal wire goes to ground. BTW, I know it's 14v ea, but 12v keeps it simple.
ida34
Well-known member
Putting a non isolated ground alt on a cucv will not send 24 volt into the 12 volt stuff. It will cause the 12 volt circuit to short to ground at the alternator. If you attach the batteries after putting on the alt then you will get sparks at the battery and probably blow it up. If you connect to the alt while the batteries are hooked up then it will spark at the alt. Either way you have a short to ground at the passenger's side alt since this is where the 12 volt positive meets the ground negative. Not to try to be contrary, but the passengers side alt is not isolated from the rest of the cucv electrical system. It actually connects to the 12 volt side and as others have already pointed out, the 12 volt positive is actually the negative for the passenger's side alt. This is why it must be isolated from the alternator case since the case makes contact with the 12 volt negative side. One must remember that ground and negative are not the same thing. There were many vehicles in the past that used a positive ground. The cucv uses ground for the negative for the 12 volt and the 24 volt system. I think the perceived mystery lies with the the general public confusing ground and negative.
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mangus580
New member
Simplest way to think of the CUCV electrical system, is to think of your flashlight. You put 2 batteries in it, in the manner of '- + - +' thus creating 3v for the bulb.
The cucv is the same thing, only using 2 12v batteries, making 24v. Alternators wire up the same way. Only difference is, on the CUCV, you need 12v for some things, so they take it out of the middle of the 2 batteries.
The cucv is the same thing, only using 2 12v batteries, making 24v. Alternators wire up the same way. Only difference is, on the CUCV, you need 12v for some things, so they take it out of the middle of the 2 batteries.
cool 
pbrstreetgang
Member
So when you connect the pass alt. you connect your plug, your red and orange wire to the positive terminal and the red with white stripe and black (ground) wire to your negative?
pbrstreetgang
Member
yes, then where do I connect the black wire?
pbrstreetgang
Member
Is this correct?
Attachments
pbrstreetgang
Member
Sorry, didn't mean to break any rules, just needed help
Wolf.Dose
Active member
Where you have a black wire on Gen 2 (right side). Black white goses to minus of Gen 1 (left) and from there to the diagnoses receptical, black to engine ground. So you do not need the black white, engine ground is needed, else no propper charging.
Check for reference TM 9-2320-289-20 page F-9 and F-13 (all except 1010).
Wolf
P.S.My M715 uses the CUCV series electrics and it works except the reliability of the Gens.
Check for reference TM 9-2320-289-20 page F-9 and F-13 (all except 1010).
Wolf
P.S.My M715 uses the CUCV series electrics and it works except the reliability of the Gens.
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pbrstreetgang
Member
Put the volt meter on tonight and here is what I have
No voltage on the orange (diagnostic terminal)
12 volts on the Red - White terminal
24 volts on the Red Terminal (Cable)
When it is all hooked up it arcs and tries to weld itself to the negative (black) battery terminal on the front battery
can't figure out the problem here (short) or (bad ground)
was not doing this before I took alternator off (for over charging)
No voltage on the orange (diagnostic terminal)
12 volts on the Red - White terminal
24 volts on the Red Terminal (Cable)
When it is all hooked up it arcs and tries to weld itself to the negative (black) battery terminal on the front battery
can't figure out the problem here (short) or (bad ground)
was not doing this before I took alternator off (for over charging)