Wednesday, December 9, 2020

Multimeter use EX3 OL display on multimeter meaning and measuring Example

OL  display   on  multimeter meaning  and   measuring 

What  does  OL  mean  on  a multimeter ,  this  is  the  frequency ask question  from digital  multimeter  user.   It  has many meaning ,  it  depends   on  what is  the test  function range  that you set.   I  have researched from many   multimeter manual and  found  that   OL = Over a  range  Limit  and  other detail at  measuring  explaination   when  LCD  display " OL"  mean  Over  Range  and  it  suggest user to change the range to higher range or  seek the appropriate range for  the measured amount.  For  example when  you measure  9VDC battery  and use 0.000V range  by manual selection , the testing result display OL as photo , it mean this range selected  is  not suitable for 9VDC and you have to change setting to higher range.  OL  display also displays with  other  test function  range such  as  resistor  measurement , current measurement  , capacitor test  , temperature measurement  etc.    View photo below  for   more understanding.


OL display  ,  measuring   example  for  range selection is not suitable.


check AA AAA  9V battery
        0.000   DC voltage range  set  by manual  range selection  for  9VDC battery


OL  display  on  multimeter
  It  display OL  because  this 0.000  DC voltage  range  is  not suitable for  9VDC.
The solution  is  setting to auto range  or  use higher range.  (For   OL display example only)



check AA AAA  9V battery
                      00.00V  range set  by manual  range selection  for  9VDC  battery



check AA AAA  9V battery
  It  displays  9.43V as  it  should be  (mean  00.00  DC voltage  range  is  suitable  for  9VDC )


The good measurement , you have to select the right range and right  test function before operating any measuring. Unknown value  it suggest to chose the highest range first.   For advance multimeter it has auto range , but , for low cost multimeter has only manual range selection and user need to study how to set    the  suitable  range  for  the target measurement.


OL display  when testing  condition of  components  =  not shorted ,  not connected.

The other meaning of  OL  display  on  test  function such as  diode test , continuity check . It  indicates the  condition  of component  "good"  or " bad" , defective.   OL  display  for  diode check , In case of  reverse bias it  means   diode is  not  shorted ,  2 terminal is not connected and when supply reverse bias to diode it  has to display  "OL"  as  it  should  be  =  good diode.   Example will be shown  by photo. 


OL  display  on  multimeter

                 Forward  bias  to  a   diode  ,  it  displays  0.3-08V  =  good diode.



check  Diode  with  万用表
   Reverse  bias to a  diode  ,  it displays   OL =  good diode  and  this  time  OL  mean  "not shorted "



OL  display when we  use  continuity check.   When checking switch  at  OFF position it  has to be not connected , not shorted condition. This time OL display  mean contact is  not shored (good contact).  Technical  term  NO  terminal ( Normally  open) it mean contact is not connected and the testing result get  " not connected " as it should be.  When changing   the  switch position to "ON"  it  means internal contact  is connected  or  shored , the display should be  0 ohm for good contact.  If  the display still show OL  it  means  internal contact is not connected as it should be condition ,  so OL = bad contact.


OL  display  on  multimeter
           OFF position , internal contact of  switch  is not connected , OL display means contact is not connected.  So  switch  contact  is  good  as   it  should  be.



0L  display  on  multimeter

ON position , internal contact is connected ,  the display has to show 0 ohm ( shorted) for a good switch
If   display  show  OL  it  means   not  connected  contact  , this case  it is  a  bad contact ( switch)


0L  display  on  multimeter

 ON  position  ,  the  internal contact  is  connected , but , multimeter  display   OL  means  internal contact is not connected  as  it  should   be  so this case   it  is  a   bad  switch  contact.