Generator fuel solenoid 5

[itsmoked]

This 255kW Volvo based generator has a fuel solenoid bolted on the side of the engine block. It's at an angle, if I recall correctly. It's silverish-pinkish and about six inches long, two inches in diameter. This is all from seeing it about last October.

It has three wires going to it. Why?

Whenever the system is turned on the wires promptly melt clear back to the controls. Apparently the wires melted so it was assumed the solenoid was toasted so they replaced it. The wires promptly melted again. Any ideas?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Compositepro]

It could be a mechanical problem also. If the linkages to the solenoid are not adjusted correctly, the solenoid may not be allowed to move enough to close the magnetic circuit completely. It will then burn out. Read the yellow caution label on the picture above.

 

[waross]

These are DC Compositepro.
With the DC solenoids an incomplete stroke on a three wire solenoid will result in not enough force to hold in.
An incomplete stroke on a two wire solenoid will result in burnout as the internal switch will not operate and will leave the pull-in coil in the circuit.
But, the burnout of a DC solenoid is not the result of an incomplete magnetic circuit, it is the result of the pull-in coil staying in the circuit.
An AC solenoid has a low inductive reactance and low impedance when de-energized.
This causes a high current and a high pull in force.
As the solenoid moves towards the closed position, the air gap shortens and the inductive reactance increases, dropping the impedance and the current.
If an AC solenoid does not complete the stroke, the inductive reactance will be too low and the solenoid will draw excess current.
A DC solenoid does have inductance but it does not have inductive reactance.
Keith, does this help?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Regardless, Comp's right that the two-wire will 'automatically' toast itself if allowed, whereas the three-wire will not - if correctly wired.

If the HOLD coil is only run as long as the start button is pushed then it shouldn't be toasting.

I can't switch to a two wire because the HOLD is controlled by a puny relay that would weld-shut the first time it had to power the PULL coil.

But, I do see your point about the utility of the solenoid still manually workable if the switch has failed open though a failed closed would.. not. be. good.

Quite the menu of toss-ups!



Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

The internal switch is opened by the solenoid itself and failed closed is extremely unlikely. Possible but the odds go the other way.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

I explained how to do it and what to check.
Instead they put this one, number 3, in yesterday and promptly burned it to a crisp.

They said, "they found a schematic on the internet and hooked it up that way, instead".

I told them to get a fourth one and to NOT install it but call me when they had it.

Bill I'm loving that schematic you posted, have you got a full page shot of that page of your road lighting generator?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[3DDave]

Did any of them previously work for Lucas Electric?

 

[waross]

lps for that one, Dave.

Keith, that is a photo of the inside of the side cover.
When I get a chance I'll trudge through the snow and take a wider shot.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[waross]

Here's a picture off the net.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Thanks for the try.
Had to take the star back off your schematic post since it's too blurry to make out much.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Service Manual
Take a look at page 51.
This is an alternate method.
Instead of a dedicated terminal on the ignition switch, the pull in coil is connected to the starter.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[waross]

Is this engine hard starting?
Extended cranking times may fry the pull in coil.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Dang! Nice manual. I should be so lucky.

Don't know about the cranking times. I'll check that out!

I'm trying to understand your HOLD circuit. It's not making total sense to me.

The relay contact providing HOLD is NC??
Low oil pressure while starting would energize the relay OPENing its coil circuit removing HOLD?
I guess the PULL coil seats the solenoid while cranking and as the engine starts the oil pressure rises.
The low oil switch OPENs the HOLD relay deenergizes.
The NC contact closes and the solenoid is held in?

So too the engine overheating OPENs the HOLD contact.

Not fail-safe but fail-catastrophic. LOL

Weird, but I better consider this could be the case on this Volvo.



Keith Cress
kcress -

http://www.flaminsystems.com