Mechanical Relay Not Functioning When Apply Voltage?

[elevmike]

Forgive me for being very crass , but I believe there is a base level of "knowledge" and below this , we should study a bit more before "hands on" .
like i said , I don't want to be hard , but this is a very simple problem , and OK if this is in a classroom , then there is no harm in "playing" , but if on a real machine where real fingers can get hurt , please learn a little more about basic electric circuits before going back to the machine.

Good Advise!!

 

[rsdoran]

I never saw a classroom mentioned. The original poster asked a valid question. Anyone that works on machinery has at one time or another found a component not working and replaced it and the machine starts working. LATER you find out the old part was not bad but then again I have been told that and too put it back and it still wouldnt work.

I dont know about fingers getting hurt, electricity can kill but at some point in life a person has to DO TO TRULY LEARN.

Poster, the valve you mentioned changing because you read voltage going to it but it was not working. I can think of at least 2 things that could happen to make it seem like the valve was bad.
1. Loose connection (bad wire)may not allow enough current for the valve.
2. Depending on type of valve "trash" can block them from opening or closing, removal of the valve sometimes removes the "trash". This is more common on hydraulic (fluid) systems.

As was mentioned, sometimes things will happen that do not make sense...ie a relay doesnt work but swap it with another in the machine and both work fine.

Do not be ashamed to keep a journal of what you find, what you do and why you did it. You never know when your own notes will help you in the fututre.

 

[Unregistered]

OK , time for crass .
This guy has demonstated that he doesn't have the most basic understand of circuits and fault finding - as mentioned , this seems to be on a running machine , therefore there is the possibility of injury or damage .
This is not "TRULY LEARNING" , but uneducated blundering . I complete diasgree with this method of twiddling things until something happens .
I did try to suggest that some basic course might have been more appropriate , as there is a base level necessary -what would be the case if this guy can't read the multimeter properly and frys himself ? Would you put your head in the machine while he is playing ? I think the answer to that is NO . Please remember that we owe people we give advice to a duty of care , and in this case , we should advise extreme caution for obvious reasons.

 

[TConnolly]

Do not be ashamed to keep a journal of what you find, what you do and why you did it. You never know when your own notes will help you in the fututre.

So far, the best adivce given in this thread.

All the indicator does is tell you if there's power on the coil terminals. The indicator could light, but the relay still might not be functioning.

Mike, the ice cubes I use have both an LED indicator and a mechanical flag attached to the relay mechanism, thay way you can see the state of the relay contacts even without power, they also have a manual operation button that allows you to check the contact function (also great for "forcing" without dragging out the laptop.) These are the ones I use most often: http://www.turck-usa.com/Products/Relays/ I've had excellent luck with them.