Checking an energized relay

[speedtronic]

How can we check normally open and normally closed contact of an energized relay using multimeter?

 

[Guest123]

Hi.

Dont know if I'm understanding your post correctly but the NO and NC terminals on and energised relay will be the opposite of what they are on a de-energised one in relation to the Common terminal.

I.e the NC terminal will be open if the relay is energised and vice versa.

Just a continuity test with any loads disconnected from C, NO and NC will confirm this.


Or have I completely misunderstood your post???

 

[speedtronic]

YES Lenny, you have misunderstood my post. My question is how to check whether some contact is open or closed in an energized relay/circuit using multimeter?

 

[Jurasic Spark]

YES Lenny, you have misunderstood my post. My question is how to check whether some contact is open or closed in an energized relay/circuit using multimeter?

I think you are asking how to check using your multimeter as a voltage tester on your energised relay:

Connect 1 probe to 0v of the circuit.
Test at the feed side of your n/o contact to make sure you have a voltage there. Then test at the other side of the n/o contact and if the voltage is also there then the relay contact has worked.

Similar for n/c but when energised this contact will be open circuit.

You could also connect the volt tester across a contact. A reading of 0v will indicate no potential difference, a closed circuit at that point


A better way would be to isolate the circuit and test the contacts with a continuity tester.

 

[Darkwood]

Think i get your jist, if you look on the side or top of the relay it will have a diagram as to what terminal leads to its counter-part, common to n/o and common n/c there may be 2 or 3 seperate channels eg 8pin or 11pin respectively if the relay isnt energised then the terminals will link as per diagram and vice versa when energised use a stardard ohms range to check this, but dont check this way if its got wires connected other than the coil supply disconnect to prove this way or use a voltage reference to check when any wires are connected.

Be careful if testing live as the circuits going through the relay or connect to it may be via transformer and could be isolated from earth, you need to understand the circuit layout before understanding your results.

 

[thepurple1]

This is basic fault finding, does it need to be explained

 

[Darkwood]

We all start somewhere, i remember my first attempt to fault a direct on line contactor it was just like a mind bomb of complication but after you've done it a few times it all fits into place and becomes second nature and this is when its simplicity shows.

 

[thepurple1]

We all start somewhere, i remember my first attempt to fault a direct on line contactor it was just like a mind bomb of complication but after you've done it a few times it all fits into place and becomes second nature and this is when its simplicity shows.

My point is, that it comes down to training and if you have not been trained then things should be left alone. Electrically qualified does not mean fully trained.

I bet when you was doing fault finding for the first time you were not alone