OT... Hydraulic Solenoid Burning Out

[sbaum]

Ok this is Off Topic, but there is a PLC controlling the solenoid... So maybe that counts for a PLC forum.

Forgive me for my lack of hydraulic knowledge and terminology... I'm an electrical guy.

Our customer has hydraulic directional control valve (double solenoid) that has run fine for the past 7 years. A few months ago I was called in and found the one solenoid was burned out. They replaced the failed assembly and proceeded fine until yesterday, it started blowing fuses again... The very same solenoid was burned out. (This machine has around 20 solenoids.) Replaced the valve assembly again, but now it keeps blowing fuses every couple hours.

The DCV has been replaced each time with the same unit (is a Parker D1VW001CNYCF4) Also the fuse type & size has always been changed properly.

Anybody have any ideas what could be causing this?? Is it possible something in the hydraulic system could be destroying this solenoid??

Just grasping for clues and I know there's lots of knowledge here so thought I'd give it a go...

My next try is to put an RC suppressor on the solenoid. None of the other solenoids have them, but I'm hoping it will dampen the problem.

 

[dmargineau]

Is the solenoid valve controlled by a PLC Digital Output point, by a PLC Relay Output or by an interposing dry-contact relay?
The solenoid valve is drawing too much current due probably to lower than rated applied voltage or because a hydraulic system load increase (obstructed tank line?).
Compare the voltage at the control device (PLC output, interposing relay) and the voltage at the solenoid's terminals; wiring could also be an issue.

 

[widelto]

Not sure, but maybe the spool is stuck. Try to move it by hand. It must be easy to move. You have to push it using a screwdriver or something similar, there is a hole in the middle of the solenoid (externally). Have you check your oil filters ??

 

[sbaum]

The solenoid is controlled directly from a PLC Relay Output. (120VAC)
Is individually fused at 1 amp.

I've changed the field wiring already. Last time this occured the fuse in the output card (automation direct btw) blew so they replaced the output card as well.

I am planning to setup a meter to log the voltage to the valve.

So you're implying an issue within the hydraulics system could cause this problem as well?

 

[sbaum]

The spool is fine. I haven't checked filters but there are 20 other solenoids and only this one blows on the advance cycle. It is the most used cylinder in the system.

 

[James Mcquade]

sbaum,

are you replacing the coil or the entire valve?
if the spool of the valve is stuck and does not shift, it will cause the coil to overheat and burn out.

is the coil ac or dc?
could you have a dc coil on an ac valve or vice versa.

is the neutral of the coil connected to ac and dc? i had an oem do this and it created a mess one day.

have you replaced the wiring to the valve?
the wiring could be damaged or touching another power source.

if the valve is dc, use a reverse biased diode,
if its an ac valve us an rc / mov network.

check to see that the output of the other valve is not on at the same time to prevent the valve from shifting.

hope this helps,
james

 

[sbaum]

We are replacing the entire valve assembly.
Is 120vac and have verified proper voltage.

As I mentioned there is not a RC network on this solenoid, and I plan to install one, but of course everyone is asking... Why did it work for 7 years then suddenly this?

I have monitored that only one coil is energized at a time.

 

[dmargineau]

The solenoid is controlled directly from a PLC Relay Output. (120VAC)
Is individually fused at 1 amp.

I've changed the field wiring already. Last time this occured the fuse in the output card (automation direct btw) blew so they replaced the output card as well.

I am planning to setup a meter to log the voltage to the valve.

So you're implying an issue within the hydraulics system could cause this problem as well?

Yes; a hydraulic "load" increase could cause a higher drawn current.
Are both solenoids burning up or only one?
I have seen obstructed "Tank Drain" lines causing the same issues as yours.
Also, as per James' suggestion, verify that only one solenoid is energized at any time; eventually ladder logic interlock the two outputs with a Normally Closed "contact" of the opposite one.

 

[sbaum]

Yes; a hydraulic "load" increase could cause a higher drawn current.
Are both solenoids burning up or only one?
I have seen obstructed "Tank Drain" lines causing the same issues as yours.
Also, as per James' suggestion, verify that only one solenoid is energized at any time; eventually ladder logic interlock the two outputs with a Normally Closed "contact" of the opposite one.

Only the solenoid for the cyclinder advance is burning up.

 

[keithkyll]

An RC network isn't going to help. On a solenoid, the core must pull in to the coil. If it doesn't, the coil burns. Must be a hydraulic problem somewhere, causing the plunger to hang.
When given the chance, I replace these type with air driven, and add two air pilots.

 

[CharlesM]

If the valve has a connector you may have a bad connector. Sometimes the indicator lights will go bad and cause this type of thing.

 

[Sidewinder]

Any d.c. bias on the supply or superimposed on the coil supply lines?
Does this valve get used the most on the machine/cylinder?

 

[Sidewinder]

Oh, and what is the oil like, have you had a sample done?

 

[jawolthuis]

There is a steel core in the center of the coil. When the coil is first energized the current is high, but as the steel core is pushed into the valve by the magnetic field, the current will drop way down.
If there is anything in the valve preventing the spool from travelling all the way, then the current will stay high in the coil, and it will burn up.
Make sure the valve spool is travelling all the way. If you can check the current while the coil is energized, you can see what I mean.

 

[strantor]

Some solenoids aren't rated for continuous power. Dual solenoid "push/pull" type with no spring return to center are sometimes only rated for a "pulse" to shift the spool from one side to the other, and then it stays there. If you leave the power applied to one of these type coils, it can burn out. I know, because I just did this not too long ago; burned up a customer's solenoid because the timer I installed had a latched output and I didn't realize it was supposed to be a pulse because I can't read German.