Solenoids - anyone know where to buy the basic parts?

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boydage

Joined Oct 7, 2016
82
Typical world we are filling it up with our useless rubbish. I actually blame the manufacturers and the profiteering that comes from the spares and the excessive prices they come at making people throw away good products because they are too expensive to repair. I want to repair the inlet water solenoid for my fridge (open circuit). The valve, is NZ$288.00. Yep. We are talking about a$10 valve.

So was wondering if anyone knows of a supplier who would be able to sell me a solenoid coil. It needs to be 220-240VAC, 30watt, and have a 10mm hole in the centre. I have searched New Zealand for one - and short of risking it by buying a bunch of different ones (already attached to a valve) and hoping I get one that will be correct. It would be good if I can just buy what I need.

Anyone know where to look?

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oz93666

Joined Sep 7, 2010
737
30W seems a lot of power for that.... are you sure it's the coil that has malfunctioned ??? I don't see why this should happen .

If the coil terminals do show zero resistance might as well open it up , slight chance you can find the break (perhaps near the terminals) , and fix it ...

If the break is in the middle of the coil it could still be fixable or for a perfect job buy some enameled wire and re-wind it yourself .

Alec_t

Joined Sep 17, 2013
12,160
Agreed re the re-wind. If the coil bobbin is a conventional cotton-reel shape it should be relatively easy to rewind it. Use the existing wire as a guide when buying new.
Alternatively, can you adapt the plumbing to accept a different brand of valve?

AlbertHall

Joined Jun 4, 2014
11,401
As this is a 230V winding it will probably use very fine wire which requires a lot of care to wind many turns without kinks or breaks.

oz93666

Joined Sep 7, 2010
737
I don't understand what could cause an item like this to fail ...

It's a sealed wire coil , it doesn't degrade , presumably it's designed to tolerate the hottest day , so what can suddenly go wrong?

Joined Jul 18, 2013
23,381
As a last resort, if you do fit another style, it would definitely pay to obtain a DC version and feed it off a small bridge.
AC versions do not have the life span of the DC type.
Max.

Alec_t

Joined Sep 17, 2013
12,160
It can do. The magnetic field around a wire carrying current reacts with the field around the adjacent wire, so the wires will vibrate unless restrained (e.g. by varnish impregnation of the coil). Vibration can cause work-hardening of the copper, leading to embrittlement; or the vibration can wear away the insulation and result in shorted turns.

boydage

Joined Oct 7, 2016
82
Hi guys. Hey thanks for the replies. I actually bought one off Aliexpress that is a 60w one that comes assembled in a complete valve for about US$9 delivered, and yes mine is a 30w. Well, that is what I worked out. There are two exact same coils next to the unserviceable one, and they measure approx 1.5k ohms. Did I measure that correctly? I know its basic elec stuff but is there something different with coils? I divided the voltage, by the ohms, to get the amps, then multiplied the amps. so 220VAC divided by 1500ohms = 0.14A. 220V times 0.14 = 30w. (approx). Not counting any losses, is that the correct way to work out the size of the coil? Seems strange though as I measured a coil I have here out of a washing machine that is only 65ohms. Do the same I get 750w - booty coil no?. Anyways - yes, I did think about rewinding it. So VERY VERY carefully I put the coil in my mill, and shaved off the plastic casing 0.2mm at a time. VEEEERRRRYYY CAAARRRRFFFUUULLY............................................. only to BAM - ruined it lol. I dont recommend trying that it didnt work ha. Hey so the idea with the bridge, what does that look like in circuit form? I was thinking about doing that, use a 12vdc coil I have here but was going to use a SSR I have here to do it. But all the same am going to use the 60w coil I found https://www.aliexpress.com/item/32819144889.html?spm=a2g0s.9042311.0.0.60734c4dX3VS1g It seems the physical size is universal. And to the fridge manufacturers and suppliers of spare parts that try to charge hundreds of dollars for$5 parts making our environment fill up with unnecessary waste destroying our planet? Not to mention the mums and dads out there doing it tough and having to replace whole units because their old ones are too expensive to repair - Up yours sideways..

Joined Jul 18, 2013
23,381
You cannot calculate the current of an AC coil by measuring the resistance as you can in a DC coil, inductive reactance comes into play which is the main decider of the current.
For a 12vdc DC coil, you would need the 12vac source followed by a small bridge rectifier.
Or a 220vdc coil and a bridge.
Max.

oz93666

Joined Sep 7, 2010
737
It can do. The magnetic field around a wire carrying current reacts with the field around the adjacent wire, so the wires will vibrate unless restrained (e.g. by varnish impregnation of the coil). Vibration can cause work-hardening of the copper, leading to embrittlement; or the vibration can wear away the insulation and result in shorted turns.
So that's with AC only??

Worth using a bridge rectifier and capacitor to get DC Then the coil will last forever ??

Also DC will generate less heat in the solenoid for the same pull as no heat producing hysteresis loss.

boydage

Joined Oct 7, 2016
82
Thats funny I called a friend to ask about the size of the coil wondering how to measure it, thinking there must be a form of inductive resistance with an AC input....

I have a DC coil here that physically fits. Its a 12V one. The input to the 220v solenoid has a large 120ohm resistor (from memory its across the input)

Anyways - not having built a circuit with a rectifier and cap before to power a solenoid, how do I go about this? I need to rectify the voltage, then drop it down, and input it to the solenoid?

I actually have 12VDC supply inside the fridge already. Tried to fix the power supply section of the icemaker board with the help of someone on this forum a while ago. To no avail. So we plugged 12V into the board and got it going. So I have 12vdc on hand. What if I just put a little 220v relay I have here into the system and 12vdc on the other side to run the solenoid? And a cap across the solenoid? Size?

Thanks

Joined Jul 18, 2013
23,381
Inductive Reactance.
The only time a AC coil/relay/solenoid has the advantage is at pull in time due to the initial high current, once it is in efforts have to be made to keep it retained, and any loss of retention causes excess current.
You cannot simply apply a rectifier and capacitor, unless experimenting with much lower voltage, the wattage should not be exceeded.
If switching to a DC coil, you do not need a capacitor however, just a bridge rectifier using the AC voltage value the same as the coil voltage rating.
So if low voltage coil, a small transformer would be required.
Max.

boydage

Joined Oct 7, 2016
82
Thanks Mr Headroom. The actual is 230vac here, I have a 12vdc coil. There is a large 120ohm resistor across the input to the original solenoid - I dont need that anymore huh?

Ok, a rectifier and a small control transformer. I will do that.

Joined Jul 18, 2013
23,381
No resistor required.
Max.

Alec_t

Joined Sep 17, 2013
12,160
A reverse-biased diode across the relay coil would help to reduce arcing at the relay contacts and prevent back-emf from frying whatever else is connected to the 12V supply.

Edit: Ignore. Was thinking of a different thread .

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shortbus

Joined Sep 30, 2009
8,722
A reverse-biased diode across the relay coil would help to reduce arcing at the relay contacts and prevent back-emf from frying whatever else is connected to the 12V supply.
I don't understand this. How does a diode across the relays coil affect the contacts?

Phil-S

Joined Dec 4, 2015
219
I worked a lot with solenoid valves in process automation. There was only one brand that had zero failures, 100% reliable and that was Burkert.
Come in all configurations, wide range of coil voltages. Pricey, yes, but not when set against the cost of process downtime. It comes down to details like materials used, particularly 'O' rings and other parts in contact with the fluid.

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