Contents
What is a metal oxide varistor used for?
Varistors are used to protect a circuit from high voltage surges. When a high voltage surge is applied to a circuit, the outcome is usually catastrophic to the circuit.
How do I select a MOV varistor?
Application Guidelines
- Step 1: To find the voltage rating of the MOV, allow for 20% headroom to account for voltage swell and power-supply tolerances: 24 V dc × 1.2 = 28.8 V dc.
- Step 2: To determine which MOV disc size to use, first identify the MOV series that minimally meet the 1000-A surge requirement.
What is MOV capacitor?
An MOV is a voltage dependent device which has an electrical behavior similar to back to back zener diodes. pulse is absorbed by the Varistor, thereby protecting vulnerable circuit components.
Which is the best characteristic of a MOV?
The best characteristic of an MOV is its ability to absorb high current content accompanied with the voltage surge . Depending on the MOV specification the current absorbing capacity of an MOV could be anywhere between 1 amp to a massive 2500 amps
What is the current rating of a 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.
What causes the performance of a MOV to change?
Another main reason that affects the performance of a MOV is the energy rating. When there is an increase in the energy rating, there will be an exponential change in the life of the varistor. Thus, there will be a change in the transient pulses that the device can manage. This increases the clamping voltage when each transient breaks down.
How does a metal oxide varistor ( MOV ) work?
What is a MOV (Metal Oxide Varistor)? MOV is simply a variable resistor, but unlike potentiometers, MOVs can change its resistance based on the applied voltage. If the voltage across it increases the resistance decreases and vice versa.