If the temperature of the coil increases what will happen to the directional control valve's function?

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The short answer to this is: the solenoid coil will fail and therefore the hydraulic valve itself will cease to function. In AC electric coils the resistance or impedance of the coil is lowest when the solenoid is open, i. Impedance increases as the plunger is pulled into the closed position. As a result, the current draw of an AC solenoid is highest when the solenoid is open plunger out and lowest when the solenoid is closed plunger in.

The high current draw of an open AC solenoid is known as inrush current.

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And the current draw when the solenoid is closed is called holding current. AC solenoids can only dissipate the heat generated by their holding current. This means it's very important for the plunger to close completely when an AC solenoid is energized.

In other words, the high inrush current generates more heat than can be continuously dissipated by the solenoid. So if the plunger is not able to be completely pulled into its coil - due to a mechanical problem with the valve for example, then the insulation around the coil windings will burn and the coil will short out. But what could go wrong with a hydraulic valve that would stop the solenoid plunger from being pulled in completely?

Well, contamination is a common cause. When hard or soft particles invade the clearance between the spool and its bore, the solenoid may not have enough power to fully shift the valve's spool. This is often referred to as "silt-lock". If silt-lock is the problem, then replacing the solenoid is a waste of time. Replacing the entire valve will BUY some time - until it too becomes 'silt-locked'. The solution of course, is to get the contamination problem under control.

Another problem presented by the inrush current characteristics of AC solenoids, is the possibility of overheating due to rapid cycling. Each time the solenoid is closed it is subject to the heating affect of the high inrush current. If the solenoid is switched on and off too rapidly, the successive inrush currents can generate more heat than can be dissipated, leading to failure of the solenoid.

Still, an AC solenoid can be cycled quite rapidly. To give you some idea, a class H solenoid, which has insulation rated to C, can be safely switched twice per second. But a DC solenoid with class F insulation rated to C can be cycled four times per second without any fear of overheating. And the nice thing about DC solenoids is they don't burn out if the plunger doesn't completely close - due to silt lock or any other reason. If you enjoyed this article, you'll love Brendan Casey's Inside Hydraulics newsletter.

It gives you real-life, how-to-do-it, nuts-and-bolts, hydraulics know-how? Listen to what a few of his subscribers have to say: Can't Put It Down? I get magazines and e-mails like this all the time. I never find time to read them.

I decided to read Issue 30 and I couldn't put it down. I'll make time from now on.? Richard A. The knowledge I've gained from this newsletter has been so valuable it has earned me a raise!? Love It - Keep Them Coming? I just love this newsletter.

As a Hydraulics Instructor for Eaton, I make copies and distribute them to my students as I address various topics Keep 'em coming.?I've no idea if the coil takes a fraction of an amp or 20 amps when energised? I know the Milemarker hydraulic solenoid only takes a couple of amps, but not sure about electric winches. Any thoughts please - or actual measurements? The Ifor remote is similar to a winch remote, and appears to switch a larger solenoid powering the tipper motor. I can measure the actual draw, but I don't know how it compares to a typical winch solenoid and I'm struggling to find out what the cheap remotes are rated at.

The Lodar I have switches up to 15 amps, but it's also ten times the price of the one I am looking at, so assuming the cheap ones can cope with the same might be silly. Pretty sure I measured an albright-type solenoid at 10A, and therefore didn't bother relaying it.

The coil will only draw a fraction of an amp. If you have a good multimeter it's easily checked. I would guess at less than. Slipped a decimal point Les! I suspect that the confusion between 10A and 0.

Winchmax have replied and said "The remote controls are designed to produce a 12v signal only and are not really designed to be used as a stand alone switch - they would however be able to manage amps.

I guess I'll need to measure the current drain on the Ifor with a meter and see where it falls in the range of outcomes. I was thinking amps would be about right for a typical Albright type solenoid, but wasn't sure. Thus using the worst case power figure would give a current of 2. Continuous operation.

When I fitted a Milemarker to my Defender I added a cheap wireless control as well. But it didn't work, it would energise the solenoid and immediately cut out again because the currect demand was too high. It worked fine with electrical winches, so the solenoids in the valve block must have a higher current draw.

You could have the same problem with the tipper, depending on the size of the valveblock. OK, thanks, that's useful to know. I have a Lodar on my Milemarker which works perfectly but that has solid state switching for up to 15 amps so not a problem. If I can't get a cheap wireless to work then I'll probably just hard wire a waterproof toggle switch into the metal box.

Can you still not use a cheap wireless remote to trigger a relay which in turn energised the coil on the solenoid valve or am I missing something? Yes I probably can, but given that it all lives in a not very weatherproof metal box under a trailer which will be damp from condensation, rain, road spray etc, I'm keen to keep the electrics to a minimum.

Which I know makes it a dumb idea to fit a wireless remote, but I want one.I purchased some high pressure solenoids off shore for a project 24 volt coils. The tag indicates 28 watt and in order to spec. Since I was unable to get the info I needed from buying agent I am asking the question, am I on the right track with this calculation or is there more to know.

I am not involved professionally in electronics, an obvious statement.

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Thanks in advance for your consideration. For a 24VDC solenoid coil, 1. When current is flowing, the rated 28W will be dissipated as heat in the coil winding. If you have several of these in a small enclosed area, the heat build up may be excessive. Good luck! Thank you mjb and old salt. Very much appreciated you sharing your wisdom and experience. You don't state whether you are dealing with AC or DC electrical. If it is DC your calculation is correct.

If you are dealing with AC the calculations are more complicated than the simplicity of Ohms Law. In AC you are dealing with several different factors but you would get an answer close to the resistance of the DC calculations. This is called "reactance".

When Inductance and Capacitance are introduced into the calculations, that's when things get much more complicated.

hydraulic solenoid amp draw

This may be an oversimplification to some persons but for most purposes it is near to the exact answer. Adding inductors, capacitors, phase angle, etc. Would there be an inrush current, even with DC? I don't know, just asking. I can't think of an obvious reason, but there might be some effect as the armature moves towards the electromagnet.

In any case I would suggest for design OP uses a safety factor at least 2 on the calculated 1. Yes, there would be an inrush unless there is some external circuitry to reduce or eliminate it. Not usually on DC - the resistive component dominates. With AC when the armature or solenoid is open the current is higher until the armature pulls in changing shortening the magnetic path length.By spDecember 7, in Technical Topics.

How much current does the starter solenoid draw? Not for the actual starter motor, just need to know the current draw for the switch. About 50 Amps but just for a split second, as soon as the contacts close it drops down to 10 Amps. BTW this is the main reason other model Guzzis suffer from "Startus Interuptus" they have the current run through the ignition switch and miles of spaghetti, too much resistance for the current required.

See if you can find a Guzzi schematic that shows 2 coils, I wonder if they are aware of it? If you are thinking about doing away with the relay keep in mind Voltage drop due to the high current, keep the wires short, a 20 Amp fuse is appropriate. So you are saying that this line coming from the starter relay jumps to 50A then drops to around 10A when the starter button is pressed?

The Bosch starter has a much heavier winding on the armature but the solenoid coils draw a similar high current. That sketch is from one of your wiring diagrams. Is it really just getting away with it because it happens so quickly?

Some owners have found the 15 Amp fuse pops so increase it to a 20, more so on other Guzzis I think where they have too much resistance and the solenoid sits and thinks about pulling in.

I don't know what the cut-off is between pulling in or sitting there, I suspect 25 - 30 Amps but it's just a guess. BTW if you look at the sketch you posted you will see when you take the finger off current can flow backwards from the armature side of the contact thru both coils in series to chassis, In this case the strength of one solenoid is supposed to work against the other to cancel out the field. I have seen one Bosch where it wouldn't let go until the battery lead was broken.

In your opinion, can the starter, neutral and clutch switches handle this current if I was to rewire the starter button to go through them and to the starter solenoid directly instead of through all the relays? This will work until it stops working. That relay is not in this circuit just for entertainment. A relay is there to handle the current the other components shouldn't. I know they make slow blow fuses for glass tube type fuses. If you are thinking about having a start button close to the starter it would probably be ok.

Solenoid amperage question

Some ignition switches have a spring loaded contact that may be man enough. Think about using one of the older cube relays mounted right beside the solenoid that would keep the heavier wires really short. The relay coil wires only pass about mA so they can be tiny.

Think about the safety aspect, the starter should be disabled by removing the key, kids love to push buttons. Thanks Roy. I will not attempt to route it directly, will use switched power through the clutch switch only, to a relay, which will send full juice through to the solenoid. You can post now and register later. If you have an account, sign in now to post with your account. Paste as plain text instead. Only 75 emoji are allowed.Electric-hydraulic dump hoists are used on many small trucks in construction and landscaping businesses.

These hoists provide a means of installing a dump body on a truck that requires no mechanical connection to the drivetrain and are simple to operate. These hoists are also quite reliable, seldom breaking down and you can fix them quickly on the rare occasion when a problem occurs. The electric-hydraulic unit that does the work of lifting the bed of the dump truck is a complete motor, pump and reservoir in one compact unit.

A cable from the vehicle battery is run to the solenoid on the pump unit, and a small gauge wire from the energizing terminal of the solenoid is run to the control switch in the truck cab. Some models have two solenoids, one for up and one for down, and in this instance two wires run to the control switch.

Pressing the up or down buttons in the cab energizes the pump solenoid. When the bed fails to lift, check a few simple things. Determine if the pump is running when the "Up" switch is pressed. A running pump indicates either that the hydraulic fluid level is too low or that the load is too heavy for the pump to lift.

It may be necessary to off load some of the cargo to lighten the load to the point where the hoist can lift it or to add hydraulic fluid to the reservoir.

If the pump does not run when the up button is pressed, ensure that there is battery power to the pump solenoid. You can determine this quickly with a volt test light. Power here indicates that the problem is in the control switches, the wiring, the solenoid or the pump motor. Jump a wire temporarily from the battery cable to the energizing terminal of the solenoid to see if the pump starts to run. If it does, the problem is in the control switch or wiring; if the pump does not run, the problem is either the solenoid or the pump motor.

If the solenoid makes a heavy clicking sound when energized, it's likely the motor; no sound would point to a bad solenoid. This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us. About the Author This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information.I use two propane bulkhead cabin heaters.

They are light, simple and draw only an amp when in use. Except, having two propane tanks I have a catamaran, so two hulls to heat means using two solenoids that each draw nearly an amp on their own. This doubles my electrical draw for heat on a limited house bank. I'm hesitant to eliminate the solenoid for obvious reasons but looking for another way around the problem.

Yes, they are very power hungry. It is a characteristic of the beast. Something like an automobile start switch could accomplish this. A resistor in series with the "Run" position would lower the current. Some kind of geeky R-C circuit might work as well.

Maybe somebody makes a little box that does this? Prevents the solenoids from cooking themselves to death, too.

hydraulic solenoid amp draw

I don't much care for those power hungry valves either. There used to be a bistable gas solenoid valve marketed for this out of Britain, but I can't find it anymore. Let me expound on my solution.

What I did was to remove the solenoid coil from the LP valve exposing the stem of the valve. Inside this stem is a plunger which is activated by the electromagnet coil.

The net result is that I can now leave the amp sucking LP switch in the off position and still have a convenient way to turn the LP on or off as necessary. I will try to take the time for pictures soon if anyone wants them. The safety issue would be that most control circuits and sniffers do not contemplate this sort of valve and would not shut off in the event of a sniffed leak.

You would need to modify the controller. I suspect that for a manually switched circuit you could remove everything except the resistor and capacitor and add a high value discharge resistor to the cap. But, I could very well be mistaken and there's that whole immolation thing.

hydraulic solenoid amp draw

How many amps is worth a point of fiery death probability? In my usage, no sniffer, it is the red lamp that reduces the risk of immolation.

hydraulic solenoid amp draw

So the type of circuit that energizes the immolator while also lighting the lamp does not matter much. Here is a "starting" type switch that would work kinda pricey? A 6 Ohm 5 Watt resistor in the ON leg might do the trick. Reduce the power by about half. Turn on the valve, turn on the switch and vice-versa.Discussion in ' General Conversation ' started by IslanderMar 15, Shamrock Boat Owners' Club. Mar 15, 1.

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Messages: 3, Likes Received: 6. Mar 16, 2. Well this dog didn't hunt so after a few phone calls: The solenoid has 0 amp draw from the ignition switch, all the ignition switch does is ground the solenoid by closing the ignition circuit.

The only amp draw on the ignition switch are: 1. Mar 16, 3. Messages: 13, Likes Received: 9. Just saw this thread. That description isn't correct. I don't know, off hand, what the current draw is for the coil in the starter relay but my guess is that it would be on the order of at least an Amp or two and would only be there during cranking.

Also, the electric choke heater element DOES draw current for the whole time the IGN switch is turned on, otherwise, the choke would try to close. The electric choke heater, on my spare Holley carb, has a cold resistance of 12 Ohms. That would give an approximate, continuous current draw of 1 Amp while the engine is running. That resistance might go up as the heater gets warm, reducing the current a bit after running for a while.

So far as the gauges are concerned, I don't know what the operational draw would be but the lighting circuit doesn't usually pass through the ignition switch but through a separate lighting switch on the console, tied to the NAV lights that's how mine is wiredso that current wouldn't be in the IGN switch tally. Assuming about a 3 - 4 watt bulb in each instrument, the individual lamp current draw would be in the 0.

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LEDs would be much lower at only a few mA each. My boat is still under cover damn sleet and rain!

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Mar 16, 4. Kurt thanks for your informative post. I also did believe that the ignition switch in the start position feed current to the solenoid, so that the solenoid can "push the internal plunger" and this would take current Accordingly this action by the ignition switch has no current draw?

Also, the ignition coil not the starter relay coil is fed current by the alternator field wire, not by the ignition switch. My understanding here is that the ignition switch "excites" the alternator at the same time that the starter spins the engine, so the coil is fed from the alternator "field" wire. I am going to test the resistance as you suggested and post up the results. And it is quite possible that my understanding here is all incorrect.

Ignition Switch Amp Draw

The choke issue was helpful I thought it only worked with a cold engine. And yes my gauge lights are fed from a separate intrument lights circuit - which is fed by the same cable that feeds the ignition switch circuit. Thanks again.

Mar 16, 5. I beg to differ with what the PCM tech said. If what he said were true, the engine would shut down immediately if the alternator failed and that is just not the case. What is true is that once the engine starts, the alternator generates enough current to carry the engine electrical load but the current still passes through the ignition switch. Some, more recent, alternators single wire do not have the field excitation wire - they are internally powered once the alternator RPMs get high enough to generate the exitation current.

In that case, the green wire would not be connected. If you look at the attached wiring diagram of a PCM Ford engine ignoring the electric fuel pump circuityou'll see that the purple wire ignition circuit, pin 6 in the engine harness connector - 16 wire on my boat both excites the alternator field green wire AND supplies current to the ignition system and the carb choke heater.


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