I tried tracing the other wires back to the panel the next day and the manager said they will be the same as I told him the previous day. So
he gave me another task instead.

If the machine looses memory, that's their problems. They gave me too hard task to start with. No diagrams to go on.
Thats the link to the manufacturer. I'm trying to get the spec. But when I checked previously, they didnt have anything on it.

http://www.elpress.com/Elpress-EN/Industrial-washing-systems/Washing-systems/Crate-washers

 

I'm surprised, if still in business and a going concern, I would expect them to have records?
What is the qualifications of your manager?
Max.

 

I have no Idea what qualifications he has but he seem to be very experienced. There is a cabinet where Manufacturer's instruction's are kept
and I looked through them for about 45 minutes till I saw the manager again and asked him and he said there was none.

I remember coming for the interview and he took me around the factory asking questions about control panels and I kept telling him as long as there was I had access to the wiring diagrams I would be okay and he said they don't always have them.

I may have more qualifications than him but he may have more practical experience than me.

 

Well going back to the original problem, it is of no use to trace the output of the relay that ends with a missing solenoid.
You have to trace the other contact back to the source and find the voltage rating of the source, only then can you come up with a suitable solenoid coil, either original, or failing that, a complete replacement solenoid of the right voltage and volume capacity.
Max.

 

Absolutely. I needed to know where the supply to the relay was coming from to be able to workout
the supply voltage but the trace ended at that relay and there was no circuit diagrams to I guessed and told him what I thought.
May be it was wrong. He know what it was.

 

Well, What I have learned today was that although the inputs to the relay can be AC, we can drive a DC load from the output pins as long as it does not exceed the specified rating.

If correct then Thank you very much. If wrong then I've gotta go back and read the posts.

 

Since you are apparently trying to find out what kind of coil the solenoid valve use, is there by chance a tag or label on the valve itself that may lend a clue? I know it's a long shot, but may be worth looking into.

 

Yes that is basically correct, it is NOT the coil source for the relay that you need to be concerned with, it is the other contact to the one that feeds the solenoid valve itself.​

This should lead you back to a source you can identify as AC or DC and the voltage that the missing solenoid operated at.
Max.

 

Since you are apparently trying to find out what kind of coil the solenoid valve use, is there by chance a tag or label on the valve itself that may lend a clue? I know it's a long shot, but may be worth looking into.

Absolutely not. I looked, and looked, and looked on the valves till my eyes were popping for anything on the taps, but there was none.
Cheers

 

Measure the voltage on one of the other operational solenoids (other valves). That'll clue you in on what voltage you need as a source for the solenoid circuit you're tracing out. (remember my drawing) Then disconnect the solenoid you're measuring for voltage. Check the coil resistance itself (no voltage applied, isolated from all other circuits and sources). The resistance won't give you a definitive answer, but it should give you a clue as to how much current the solenoid draws.

I'm certainly no expert on coils and magnetics, but I believe the resistance is lowest with DC and only goes higher with AC - the higher the frequency the higher the resistance. Actually I believe it's called impedance. Similar to resistance but varies with frequency.

Someone here must be knowledgeable enough to be able to clue you in on how many amps the solenoid will draw - likely at 60 Hertz. If it's DC (doubtful) then your resistance reading will be definitive. Apply a little "Ohm's Law" to the circuit and you'll be able to figure how many amps it draws. (keep in mind I'm talking about measuring an active solenoid. and also keep in mind the solenoid under measurement needs to be disconnected from all electricity. I don't want to be responsible for shocking your azz)

That's the first thing. The second thing is - is there a voltage source for your relay contacts to connect to? If not then it may be that someone before you has de-energized the system to prevent accidental injury, fire or death. If your relay has a control voltage (for the coil) but no power source for the contacts then that may be something in addition you need to repair.

 

I'm certainly no expert on coils and magnetics, but I believe the resistance is lowest with DC and only goes higher with AC - the higher the frequency the higher the resistance. Actually I believe it's called impedance. Similar to resistance but varies with frequency.

.

Actually the resistance is higher with a DC coil of the same voltage, with an AC solenoid/coil, inductive reactance comes into play which in conjunction with the resistance, limits the current.
Max.

 

I don't see much evidence of DC supplies so although Europe went to the practice of DC solenoids much sooner than N.A. I would guess they were AC type.

There's a bridge rectifier to the right of the torroidal transformer. No filter cap? Used for something else?

That control panel had potential, but someone screwed up. It's why I liked using 18 AWG, but with a reduced strands like 6 in a wire. Then the wire stays were you put it.

I found a wire manufacturer that basically had a $50 minimum order and 100 feet minimum put ups. I just had to wait until they were doing the wire I needed. So, I traded low cost for long delivery. I kept 10 colors in stock.

For another project, I had 4 colors of #8 stocked too.

 

Actually the resistance is higher with a DC coil of the same voltage

OK, I thought the resistance of an 8Ω speaker got higher with the higher frequencies. But like I said, I'm not the expert. I learned something - that I had my perception of resistance and inductance bass ackwards.

Thanks Max.

[edit] Now that I think of it, inductance depends on how fast a magnetic field can be established and changed. Of a given rate, going higher will allow even less time for inductance to climb. So it now makes sense to me that at high frequencies inductance drops off. In retrospect what I said about getting an idea of the inductance based off of a resistance reading of a coil of a good solenoid - maybe that won't work. But you still get a hint of what's going on. And like I said before, I'm not the expert in this area. In fact, I'm still reading up on it. AC theory - all that stuff. LOTS to learn.

 

There's a bridge rectifier to the right of the torroidal transformer. No filter cap? Used for something else?

That control panel had potential, but someone screwed up. .

I would not have pegged that as a bridge?
I would assume that the original machine wiring appeared totally different with the wire duct covers in place, some where along the line, they have been permanently removed and wiring changes made by the look of it.
Hence the rats nest appearance.
Max.

 

OK, I thought the resistance of an 8Ω speaker got higher with the higher frequencies.

Maybe you are confusing resistance with inductive reactance?
A AC relay or solenoid coil has low resistance and relies on the inductive reactance (in ohms) to limit the current.
When voltage is first applied to a relay or solenoid, the current is virtually limited by the resistance, so current is relatively high until after one cycle and also the armature of the relay/solenoid has pulled in, this is where the full inductance comes into play to limit the current.
Effectively the resistance is in series with the inductive reactance (ohms).
Max.

 

Measure the voltage on one of the other operational solenoids (other valves). That'll clue you in on what voltage you need as a source for the solenoid circuit you're tracing out. (remember my drawing) Then disconnect the solenoid you're measuring for voltage. Check the coil resistance itself (no voltage applied, isolated from all other circuits and sources). The resistance won't give you a definitive answer, but it should give you a clue as to how much current the solenoid draws.

I'm certainly no expert on coils and magnetics, but I believe the resistance is lowest with DC and only goes higher with AC - the higher the frequency the higher the resistance. Actually I believe it's called impedance. Similar to resistance but varies with frequency.

Someone here must be knowledgeable enough to be able to clue you in on how many amps the solenoid will draw - likely at 60 Hertz. If it's DC (doubtful) then your resistance reading will be definitive. Apply a little "Ohm's Law" to the circuit and you'll be able to figure how many amps it draws. (keep in mind I'm talking about measuring an active solenoid. and also keep in mind the solenoid under measurement needs to be disconnected from all electricity. I don't want to be responsible for shocking your azz)

That's the first thing. The second thing is - is there a voltage source for your relay contacts to connect to? If not then it may be that someone before you has de-energized the system to prevent accidental injury, fire or death. If your relay has a control voltage (for the coil) but no power source for the contacts then that may be something in addition you need to repair.

The problem was none of the solenoids was working in fact there were no solenoids available, the leads were not connected to any power source. The wires were just hanging and the relays were isolated from the power source. The strange thing as well was that, the machine was running when I was asked to work on it. I saw a wire disappear into an area where I couldn't see and that required me to remove a panel and I also knew there were moving parts behind it.
I asked myself if the manager wanted me to ask the operator to shut down the system for me to carryout the task but I decided to work alongside the live machine.

 

If the machine is working happily with solenoids missing, what is the purpose of trying to identify and replace them? If the purpose is to magically improve the machine's performance, then surely that will require re-programming the PLC, the spec of which is missing?

 

If the machine is working happily with solenoids missing, what is the purpose of trying to identify and replace them? If the purpose is to magically improve the machine's performance, then surely that will require re-programming the PLC, the spec of which is missing?

I just had to follow instructions and do as I'm told. My suspicion is, they bypassed the taps to temporarily get them working until they get to replace them which is why they were working. There were at least 4 bare taps which needed this mystical component that had to be fitted.

 

Max, I have followed your post and been impressed by your knowledge of theory and systems for a long time. However, I must comment on your response in post #55 of this thread. Are you sure you wanted to say, "When voltage is first applied to a relay or solenoid, the current is virtually limited by the resistance, so current is relatively high until after one cycle and also the armature of the relay/solenoid has pulled in, this is where the full inductance comes into play to limit the current."?
I was sure that an coil opposed a change in current, therefore when voltage is first applied, the current would be minimum and rise at an exponential rate. Of course that would be for DC. For AC, the current would still rise at a rate that would, time wise, lag the voltage applied, hence ELI the ICE man.

 

The only advantage a AC relay or solenoid has is the much faster pull in than its DC counterpart, this is due to the very high initial current only limited by the resistance until the inductive reactance comes into play, lowering the current, also aggravating this and prolonging the higher current is the time it takes for the armature to move in to final position, up to this point the inductive reactance level (ohms) will be less than the final value.
After the device has completely pulled in, then it is less efficient than its DC counterpart, and requires such as shading rings to ensure the armature is retained as the AC alternates through the zero point.
IOW the drop out/hysteresis values are quite different between AC & DC coils. After engaged, a DC device can tolerate a much lower voltage and stay retained, as opposed to AC version where the tolerance is minimal.
If you have such as a Variac, it can be easily displayed by empirical testing on a sample of AC & DC relays.
I have a PDF on it if you wish me to look it up and post it.
Max.