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How do you identify a varistor?
While it may look similar to a capacitor, you can identify the device by its color, markings and location. The MOV will always be close to the equipment’s power supply and wired to a fuse. Many MOVs have a bright, solid color and are usually coin-sized. Unplug the equipment from the electrical outlet.
How do I read varistor code?
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.
How does a multimeter detect metal oxide varistor?
Turn the multimeter on and set its function knob to read resistance. Touch the meter probe tips to the MOV’s leads and measure its resistance. If it has a resistance much under 100 ohms, it has blown. Desolder and remove the remaining lead and remove the MOV from the equipment.
What is an MOV in a circuit?
▪ An MOV is a voltage dependent device which has an electrical behavior similar to back to back zener diodes. ▪ When exposed to high voltage transients, the MOV’s resistance. changes from a near open circuit to a very low value, thus clamping the transient voltage to a safe level.
How do you test for a bad varistor?
Should a varistor have continuity?
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.
Do varistors have polarity?
Does a varistor have polarity? In the case of metal oxide varistor, a zinc-oxide layer is basically sandwiched between two metal electrodes. As a result, there is no polarity.
How do I find out the value of my MOV?
The current rating of the MOV could be twice that of the SMPS rating, meaning if the SMPS wattage is rated at 24 watts at the secondary, then the primary could be calculated as 24/285 = 0.084 amps, therefore the MOV current could be anywhere above 0.084 x 2 = 0.168 amps or 200mA.
Is there a way to identify a varistor?
The problem I am having is the markings, other than the voltage don’t seem to corrolate with anything. So I’m not sure if it is a varistor or if it just has obscure markings. The markings are : 05 K385 1146 I know the k385 is the voltage from what I can find, but have no idea what the current is or what part number it matches up with.
How can you tell a varistor from a capacitor?
A metal oxide varistor, or MOV, protects sensitive electronic equipment from voltage spikes in the power line. A gadget may have thousands of transistors, resistors and other components, but only one or two varistors. While it may look similar to a capacitor, you can identify the device by its color, markings and location.
How to tell if a varistor is an electric fence?
So I’m not sure if it is a varistor or if it just has obscure markings. The markings are : 05 K385 1146 I know the k385 is the voltage from what I can find, but have no idea what the current is or what part number it matches up with. It’s currently part of the 12v input on an electric fence energiser.
How do you find the fuse holder on a varistor?
Unplug the equipment from the electrical outlet. Using the screwdrivers, open the case or cover containing the electronics. Follow where the AC line cord enters the case. The cord will pass through a grommet and will connect to a circuit board. You should see a fuse holder on the board or mounted to the case.