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What does MOV stand for in surge protection?
Metal Oxide Varistors
4032. 09/20 • e/GDT2020. Metal Oxide Varistors (MOVs) are bidirectional and non-linear surge suppressor devices that are widely used for limiting voltage during a surge or transient event in a broad variety of applications.
What is an MOV in an electrical 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.
What is function of MOV?
This type is commonly known as the metal-oxide varistor (MOV). Varistors are used as control or compensation elements in circuits either to provide optimal operating conditions or to protect against excessive transient voltages.
Why we use MOV in circuit?
A Metal Oxide Varistor (MOV) is a protection component used in power supply circuits that is powered directly from AC mains. It is used to protect the circuit from high voltage spikes by varying its resistance.
When to use a fuse to prevent failure of a MOV?
When subjected to stresses above its ratings, an MOV can fail as a short circuit. If applied conditions significantly exceed the energy rating of the device, and current is not limited, the MOV may be completely destroyed. For this reason, the use of current-limiting fuses is suggested. Q. How do you select a fuse to prevent failure of an MOV?
How does a MOV fail as a short circuit?
Q. How does an MOV fail? When subjected to stresses above its ratings, an MOV can fail as a short circuit. If applied conditions significantly exceed the energy rating of the device, and current is not limited, the MOV may be completely destroyed. For this reason, the use of current-limiting fuses is suggested.
Can a MOV be used for sustained surge protection?
The MOVs can only be used for short surge protection, they can’t handle sustained surges. If the MOVs are exposed to repeated surges their properties might slightly get degraded. Whenever they experience a surge the clamping voltage drops a little lower, after some time this can even lead to their destruction.
What kind of current does a MOV conduct?
An MOV is a 2-terminal device that has bidirectional electrical behavior similar to a configuration of back-to-back avalanche diodes. For example, an MOV rated to stand off 400 Vdc will typically conduct less than 1 mA at 400 Vdc, but it will conduct progressively more current at higher applied voltages.