Contents
How do you check if a varistor is working?
Touch one meter probe to the free varistor lead and the other probe to the connected lead. Read the resistance on the meter. If it reads nearly infinite resistance, the varistor is still good. If it reads very low resistance, the varistor is blown.
Are MOV polarity sensitive?
Are MOVs sensitive to polarity? A. No. Since MOVs provide bidirectional clamping, they are not a polarized device.
Does Ol mean infinite resistance?
open circuit
Infinite resistance (open circuit) is read as “OL” on the Fluke meter display, and means the resistance is greater than the meter can measure. Resistance measurements must be made with the circuit power off – otherwise, the meter or circuit could be damaged.
When does a varistor degrade with a DMM?
A varistor fully degrades typically when its “clamping voltage” has changed by 10%. A fully degraded varistor remains functional (no catastrophic failure) and is not visibly damaged. Click to expand… With a DMM you will read a very small capacitance or a VERY high resistance.
How can you test the resistance of a varistor?
With the varistor removed from the circuit, you can now measure its resistance. Turn the multimeter on and set it to read resistance times 1000 ohms. Touch one meter probe to the free varistor lead and the other probe to the connected lead.
How do you test a metal oxide varistor?
Heat the lead with the soldering iron until the solder melts, and remove the solder with the desoldering tool. Carefully pry the lead loose from the connection with the long-nosed pliers. With the varistor removed from the circuit, you can now measure its resistance. Turn the multimeter on and set it to read resistance times 1000 ohms.
Can a continuity test cause a beep on a varistor?
A continuity test shouldn’t cause a beep, because a varistor has much greater resistance than, say, a fuse. Try it on the Ohms range of the meter. The varistor is presumably an inrush current limiter whose resistance drops as it heats up.