Multimeter test relay

 HOW   TO   TEST    RELAY    with   digital   multimeter

Test   RELAY  with  digital  multimeter

RELAY  TESTING.    There  are may model of  relay and  some model has many terminals.  The terminal of  relay is divided    into  2  section  ;   Section 1  is   coil  , for supplying  voltage to control to operate as  switch  ON  or  OFF.  The coil  of relay   has  some resistance so good coil will show some resistance when  testing with ohmmeter.   Section 2  is  output contacts  which  consists  of  NC  type contacts  ( Normally  Close )  and   NO type contacts ( Normally  open ).

NC  type contact  ( Normally Close )  , Terminal 1 and 2  is  connected

NO type contact ( Normally  open )  Terminal 1 and  2  is  not  connected
Basic output contacts   form   consist   of   NC and  NO contact.

Step to check relay.
As   you   have  learned from above there are to type of  basic circuit  of contacts , connected and open.   So we will use continuity test function of  digital  multimer  to test the contact ; connected contacts  must be connected  as it be  and  open contacts  must be disconnected.
1. Switch off  or  unplug circuit  that  want to test.  Make sure there is not any  voltage supply to relay before testing.
2.  Find circuit diagram  that  printed on relay then find where is the coil  terminals.
3.  Test  coil  terminals  , find coil terminal of  relay and connect test leads to it.   On the sample terminal 13  and  14   is   coil   terminals  of relay.
4. Turn rotary switch to resistance test function.
5.  Good coil   present   some  resistance  value when measuring  ,  but  bad coil of  relay display
" OL  " ( open circuit )
6.  Test  NO  and NC  contacts  of relay , check all set of  contacts.
7.  Set digital  multimeter to  continuity test  function.
8.  Connect test leads  to  the  NC contact.   The  meter  will  beep  if  it is  a  good NC contact.
Bad  NC contact  , the meter does not beep.
9. Connect  the  test leads to  the  NO  contact.   The  meter  will  not  beep  if  it is  a  good NO contact.   Bad  NO  contact  , the meter will  beep ( short).
10. Test  every NO and NC contact set.  If  there is   1 contact    is bad , the relay is not good.
then find the replacement.

Find circuit diagram  of    relay under test that printed on relay's   body.

 Test coil  terminals    no. 13 and  14.
Good coil  must  present  some  measured  resistance  value. 

Test   relay
Test NC contact this example is terminals   No. 10  and  No.  2.
Connect test leads to  the  NC contact.   The  meter  will  beep  if  it is  a   good NC contact.

Test  NO  contact   this  example  is   terminals  No. 10 and  No.  6.
Connect test leads to  the  NO contact.   The  meter  will  not   beep  if  it is  a   good NO contact.

Test    IGBT   Part   2