How to Measure SCR (Silicon Controlled Rectifier) with Multimeter – SCR or Silicon Controlled Rectifier is basically a Diode that has 3 terminal legs. Two legs are an anode and cathode which function the same as diode in general, while the third foot functions as a controller or often called “gate”. To find out more about the working principles of SCR, please read: Understanding SCR and Its Working Principles.
An important thing to note is that a SCR can only conduct electricity like a normal diode when given forward-biased voltage and get a positive voltage at the control leg (gate). Therefore, there is little difference between SCR testing and normal Diode testing in general. But we can still use Multimuter in measuring or testing whether a SCR can function properly or not.
How to Measure SCR with a Multimeter
To test or measure a SCR, the equipment that needs to be prepared is a Multimeter and one short cable that we will use as a jumper or connector. The following are the steps to measure SCR using a multimeter.
Read also How to Measure Relays Using Multimeters
- Set the position of the Multimeter switch to R or Ohm (Ω) x10,000.
- Connect the Black Multimeter (Negative) Probe to the LEGS OF THE SCR Anode and the Multimeter Red Probe (Positive) to the scr cathode leg.
- Read the measurement results on the Multimeter screen, the measurement results must show a high resistance value.*If the measurement results show a very low resistance value, then the SCR is declared short/damaged.
- Connect the Multimeter Red Probe (Positive) to the legs of the SCR Anode and the Multimeter Black Probe (Negative) to the scr cathode leg.
- Read the measurement results on the Multimeter screen, the measurement results must also show a high resistance value.*If the measurement results show a very low resistance value, then the SCR is declared short circuit (Short)/damaged.
- In the condition of the Red Probe and the Black Probe are still connected at the SCR leg as in the 4th step, connect the Anoda leg and gate leg on the SCR using a connecting cable (jumper). If the SCR works properly then the resistance value that appears on the Multimeter screen will show a very low resistance value. This resistance value will remain low even if the jumper connecting cable is removed. Jumper or connecting cable serves to provide current to the legs of the “Gate” SCR or as a trigger “Trigger” SCR.
Note:
- We can also use a Digital Multimeter to measure SCR as mentioned above.
- Each type of SCR has different characteristics and specifications, if the current provided by the Multimeter is not enough to activate scr, then we can try to change the position setting of the switch to Ohm (Ω) x1,000 or x100.
