How do you choose varistor voltage?
For example, selecting a MOV or silicon varistor for that matter, for voltage, its maximum continuous rms voltage rating should be just above the highest expected supply voltage, say 130 volts rms for a 120 volt supply, and 260 volts rms for a 230 volt supply.
What is the symbol of varistor?
Varistor symbol The varistor circuit symbol can be seen to be very similar to that of a thermistor. It consists of the basic resistor symbol of a rectangle with a diagonal line through it that has a small added section parallel to the body of the resistor symbol. This indicates the no-linear nature of the varistor.
Can a varistor go bad?
If the varistor is visibly burnt through or broken, it is bad; replace it. If it appears intact, proceed to Step 3. A varistor is an electronic component that acts as a shock absorber, protecting expensive devices from harmful power surges. The varistor will likely be wired to a fuse holder.
How do you size a varistor?
What is maximum clamping voltage varistor?
Varistor Voltage (Max): Sometimes called clamping voltage (MAX), is the approximate max voltage the varistor will conduct (or pass through to the circuit) for a specified peak pulse duration without causing device failure if operated within spec.
How do I select varistor value?
Consider the maximum continuous voltage that will be applied to the varistor including any high line conditions (i.e., 110% or more of nominal voltage). Ratings are given for continuous sinusoidal AC and DC voltages. If a nonsinusoidal waveform is applied, the recurrent peak voltage should be limited to √2x VM(AC).
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.
What is the characteristic curve of a varistor?
Therefore, the current-voltage characteristic curve of a varistor is highly non-linear: high resistance at low voltage and low resistance at high voltage. Metal oxide varistors are currently the most common voltage clamping devices and can be used for various voltages and currents.
How does a varistor respond to a power surge?
For example if there is a power surge, the varistor, normally having a very high resistance, responds to the voltage spike by absorbing its energy with a very low resistance. This may blow the equipment’s fuse, but it will protect the expensive electronics.
How is a varistor like a shock absorber?
How to Test a Varistor. A varistor is an electronic component that protects expensive devices from harmful power surges, much like a shock absorber. For example if there is a power surge, the varistor, normally having a very high resistance, responds to the voltage spike by absorbing its energy with a very low resistance.