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Author Topic: Voltages through a solenoid?  (Read 2526 times)
belfert
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« on: March 12, 2011, 05:29:39 PM »

If I buy a 12 volt continuous duty solenoid can I use 12 volts to control the solenoid and then run 24 volts through the switched side?

I've been looking at documents from Cole-Hersee and such, but I haven't found an answer yet.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #1 on: March 12, 2011, 05:46:41 PM »

Yes that would be no problem as long as you stay within the contact's current rating.
The additional voltage across the contacts won't be a problem - the only concern may be an arcing-the-contacts-upon-release issue when running contacts at higher than design voltages but in general you won't experience any of that until you get above 40 volts.
You should be fine.
« Last Edit: March 12, 2011, 06:24:33 PM by boogiethecat » Logged

1962 Crown
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« Reply #2 on: March 12, 2011, 06:31:03 PM »

 what does a continuous duty solenoid do can someone explane thanks john
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belfert
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« Reply #3 on: March 12, 2011, 07:02:53 PM »

Solenoids are very similiar to relays except they can generally handle higher currents.  Most newer buses will have a number of solenoids in them for such things as only passing power to the A/C motors when the engine is running.  My bus has at least three large solenoids in it.

Good to know that I should be able to pass 24 volts through a solenoid that has a 12 volt control circuit.  The current would be well below the rating of the solenoid.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #4 on: March 12, 2011, 07:02:56 PM »

I don't agree that doubling the voltage in a 12v rated solenoid won't arc, in fact it probably will since it is not designed for double the potential between the contacts.

An engine spark plug is nothing more than two close contacts at a (Very) high potential.

A continuous service solenoid is a totally different animal than an intermittent service one (Like a starter solenoid) even though they look the same. The supplier will know the difference.

I would guess that a continuous might work as an intermittent at moderate amps but not the reverse, but this is just a guess. I also would guess that an intermittent will handle much higher amps than a continuous, but, as I said, these are guesses.
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Gary '79 5C
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« Reply #5 on: March 13, 2011, 03:05:10 AM »

Brian,

I do not remember if you still employ the coach air conditioning on your bus. As you stated, the 200A cont duty solenoid is what I would want. If you have ditched your coach air, I would salvage those solenoids, I did. If not check out a salvage bus for parts as those solenoids can cost $200 used, $400 new.

A continous duty solenoid is one which is designed with a hold in coil heavy enough to dispate the heat in continous use. "Light weight" solenoids are meant to be energized for very small periods of time. IE horn relay, starter relay, etc.

Good Luck

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06 Bill
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« Reply #6 on: March 13, 2011, 03:48:42 AM »

  The duty cycle has to do with the control winding. Most intermittent solenoids or relays would heat up and burn out
if left on without any current going through the switch contacts.    06 Bill
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luvrbus
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« Reply #7 on: March 13, 2011, 06:23:30 AM »

Brian, checkout www.texasindustrialelectric.com those are called relays but look like a solenoid these guys have about anything you need at fair prices and are good to deal with



good luck
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« Reply #8 on: March 13, 2011, 06:31:11 AM »

Brian, also check with a golf cart shop. I have taken a few off the scrap golf carts at work.
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belfert
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« Reply #9 on: March 13, 2011, 06:58:14 AM »

I can't reuse my A/C solenoid because this application requires a 12 volt control voltage and my A/C solenoid has a 24 volt control voltage.  Besides, I have already reused the A/C solenoid.

What Texas Idustrial Electric calls relays are actually solenoids.  No idea why they have them listed as relays.

What I am trying to do is use Solenoids to control my headlights.  The voltage going to the headlights now is 12 volt.  I am seriously thinking about switching my headlights to 24 volt so the switched voltage would be 24 volts.  I could probably use relays, but I figure solenoids should last longer.  An 85 amp Cole-Hersee Solenoind is only $19 each.
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« Reply #10 on: March 13, 2011, 07:11:13 AM »

What does a solenoid do ? Eagles have a ton of those and are never called solenoids 
« Last Edit: March 13, 2011, 07:15:11 AM by luvrbus » Logged

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« Reply #11 on: March 13, 2011, 10:08:54 AM »

Quote
I don't agree that doubling the voltage in a 12v rated solenoid won't arc, in fact it probably will since it is not designed for double the potential between the contacts.
An engine spark plug is nothing more than two close contacts at a (Very) high potential.


If you look closely, virtually every manufacturer that makes solenoids has any particular model available in 12,24,36, and 48 volts.  These are the coil voltage ratings, having nothing to do with the contact voltage ratings.  The mechanical components AND the contacts are identical for all versions of the model; just the coil winding thus the coil voltage changes. In fact, the contacts ARE designed for up to 48 volts in  all solenoids that can be purchased in the coil voltage ranges mentioned above, regardless of their coil voltage.  I'd place a very solid bet that this applies to virtually ALL commercially available solenoids.  

Yes engine spark plugs are two contacts very close to each other.  But they spark because they are energized with 20,000 volts or more.  This all has absolutely nothing to do with solenoid contacts arcing. The mechanism is entirely different and in this case, no comparison between the two can be drawn.
 
EDIT: "solenoid" actually refers to an electromechanical device that creates a linear physical motion in response to an electrical signal.  But in the motor vehicle industry, "solenoid" loosely but commonly refers to a type of electrical contactor or  relay that is actuated by a solenoid arrangement of it's electromechanical parts.
For the sake of not having everyone here pick on words, reference to "solenoid" in this thread refers to what might more properly be called a "solenoid actuated contactor".  But let's just set that aside for now and  call it a solenoid. We all know what it means in this context... END EDIT


For the purposes of this discussion, there is basically no difference between a solenoid and a relay other than the physical construction.

 In both cases a coil of wire creates magnetism that attracts  something made of steel to that magnetism, with contacts attached to the steel thing usually via an electrical insulating material.  Any solenoid could properly be called a relay although any relay could not be properly called a solenoid.

The difference is, in many (most) relays the physical mechanism that actuates the contact is simply a small piece of steel plate mounted near the end of a steel core of a coil, that is attracted to it when the coil is energized. It returns to its resting position because of a spring.
A solenoid differs slightly in that the core of the coil  IS the piece of steel that moves; normally held slightly away from the coil's center by a spring, it gets "sucked in" to the center of the coil when it is energized.  The reason for this kind of construction is that you can get a lot more force with a solenoid than you can with a relay configuration, which is necessary when you have heavy current contacts that you need to smash together with a lot of force upon actuation.

Here are some images of relays and solenoids so you can hopefully understand the differences..

« Last Edit: March 13, 2011, 03:29:24 PM by boogiethecat » Logged

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« Reply #12 on: March 13, 2011, 11:14:27 AM »

Just to add, many "relays" today are electronic instead of using magnetic switching.  Solenoids are said to be a bit slower than relays also, but that won't matter in most uses that we have.  As mentioned in a different thread, I have several solenoids in places where simple relays would have been adequate, but that's what was available.  One thing I do like about the solenoids though, is you can hear them engage if you listen for it.  I find it reassuring.
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gus
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« Reply #13 on: March 13, 2011, 11:16:54 AM »

A relay is a remote electrical switch used to avoid running large electrical loads through switches and long wires.

A solenoid is a device that converts electrical energy to mechanical force such as in operating a push rod or valve.
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Fred Mc
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« Reply #14 on: March 13, 2011, 12:39:57 PM »

On my GM PD4106 I have removed the air conditioning stuff(condensor, compressor) but still have the heating part (fan, heater core). When the bus starts and idles the heater fan does not work until the engine is revved up a little and the "no charge" light on the dash goes out. Is this the solenoid kicking in?

Thanks

Fred
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« Reply #15 on: March 13, 2011, 01:08:34 PM »

Fred,
Relay's and solenoids have what is called a 'pick-up voltage' requirement. It takes a certain voltage to pull the relay or solenoid in. There is another voltage that is called a 'hold-in voltage' and that is the voltage required to hold the relay in and is below what the pick-up voltage is.
I'm suspect that with the 'no charge' light on because the pick-up voltage hasn't been achieved and when you rev the engine up the generator/alternator puts out enough voltage for the system voltage to increase above the relay's or solenoids pick-up voltage. If you let the engine idle back down and the no charge light comes back on but the fans keep running that is because the systems voltage hasn't dropped below the hold-in voltage.
Hope that this helps.
LJ
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Gary '79 5C
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« Reply #16 on: March 13, 2011, 02:35:01 PM »

  The duty cycle has to do with the control winding. Most intermittent solenoids or relays would heat up and burn out
if left on without any current going through the switch contacts.    06 Bill

Bill, I beg to differ, as the duty cycle has every thing to do with the contol winding, and nothing to do with the switch contact ratings.

I agree with your second comment that an intermittent solenoid will burn out if left ON.  However it has nothing to do with the current thru the switch contacts.


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« Reply #17 on: March 13, 2011, 02:43:22 PM »

  The duty cycle has to do with the control winding. Most intermittent solenoids or relays would heat up and burn out
if left on without any current going through the switch contacts.    06 Bill

Bill, I beg to differ, as the duty cycle has every thing to do with the contol winding, and nothing to do with the switch contact ratings.

I agree with your second comment that an intermittent solenoid will burn out if left ON.  However it has nothing to do with the current thru the switch contacts.




You are both saying the same thing.  I fear this circumstance as I have seen it go to a blood letting.  HuhSad Grin
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« Reply #18 on: March 13, 2011, 03:37:08 PM »

FWIW I edited my earlier post for some clarification on what these "solenoid" things are really called.  Just like everyone calling those long skinny oil filled things that make your ride smoother "shocks" when really they should properly be called "shock absorbers", people call the things we're talking about here "solenoids" when really they oughta be called "solenoid operated contactors".  But let's get real and quit picking on words... nobody is gonna go around talking about their "solenoid operated contactor" when they can say the simple word "solenoid" and get the idea across. We're just too lazy, and the short version is too widely accepted!!!

As far as continuous duty vs intermittent duty, the only difference is in the coil windings of the device.  The coils of "Intermittent" solenoids draw more power than those of "continuous" rated solenoids, and if left on for very long at all they will overheat and burn out.  If you're going to leave a solenoid on for more than say 30 seconds, you would be wise to purchase a "continuous duty" solenoid.  It can be left on all day without issue.

None of the above as a thing to do with contacts, contact current, or contact voltage.  
« Last Edit: March 13, 2011, 08:34:10 PM by boogiethecat » Logged

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Gary '79 5C
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« Reply #19 on: March 13, 2011, 04:25:48 PM »

Thanks JohnEd,

Absolutely correct. I reread the posts and I am wondering what the he11 I was thinking....  Just spent (3) days watching (5) games Atlantic 10 Basketball Tourney. Came home and thought I could read and think.

What was I thinkin ?
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« Reply #20 on: March 13, 2011, 04:32:52 PM »

I'm an idiot of course, but i have no idea what the word "Intermittnet" means... my dictionary doesn't speak that language either.
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« Reply #21 on: March 13, 2011, 04:58:49 PM »

Kind of fun to read this thread.  I have just finished the second draft of a "relay 101" article for BCM.  Should have the final to them tomorrow. 

BTW, one of the reasons that the magazine is sometimes late: authors who are 3 days past the deadline Shocked Shocked

Jim

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« Reply #22 on: March 13, 2011, 06:08:20 PM »

Fred,

That blower motor takes 30 amps on a 4104 and I presume the 4106 requires the same since the two buses are a lot alike. That is one huge motor, my lights dim when it first comes on.

A good example of solenoids vs relays is the bus starting circuit. The front panel starter switch closes a relay in the rear of the bus which closes the solenoid on top of the starter which pushes a rod which engages the starter motor gear to the flywheel.
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