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What is MOV protection?

What is MOV protection?

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.

What does a MOV do in an electrical 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.

What happens when MOV fails?

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.

What is MOV fuse?

A Metal Oxide Varistor or MOV is the blue or orange-colored circular component that you can commonly spot on the AC Input side of any Power Supply Circuit. Hence MOVs are normally used in parallel with a fuse, to protect circuits from high voltage spikes.

What does a MOV look like?

A MOV contains a ceramic mass of zinc oxide grains, in a matrix of other metal oxides (such as small amounts of bismuth, cobalt, manganese) sandwiched between two metal plates (the electrodes). They can be connected in parallel for increased energy-handling capabilities.

Does MOV wear out?

The role of the MOV is to divert surge current. However, MOVs wear out with use. As more surges are diverted, the MOVs life span shortens, and failure becomes imminent.

How do I select a MOV varistor?

MOV Selection Guide | Power Supply Peripheral Design Series

  1. (1) Wide working voltage range (mainstream 18-1800V, divided into several grades).
  2. (3) Strong impulse current resistance (up to 100-15000A).
  3. (1) Step 1: VARISTOR VOLTAGE calculation.
  4. (2) Step 2: Calculation of MAXIMUM ALLOWABLE VOLTAGE.

How do you identify a varistor?

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. The MOV will always be close to the equipment’s power supply and wired to a fuse.

What is clamping voltage of MOV?

However, MOV manufacturers list their clamping voltage at 1 mA DC based on regulatory standards such as IEC 61643-331. Figure 2 – For an industry standard MOV with a surge rating of 8/20 µs, the current rises to a minimum of 90 % of peak (T1) within 8 µs and 50 % of current decay at 20 µs (T2).

MOVDefinition An MOV, or Metal Oxide Varistor,is a voltage suppression device that clamps a transient in an electrical circuit. It is also called a Varistor, or variable resistor, because its resistance changes with applied voltage. Sometimes they are referred to as a VDR, or Voltage Dependant Resistor, by some manufacturers.

What is MOV in surge protector?

In the most common type of surge protector, a component called a metal oxide varistor, or MOV, diverts the extra voltage. As you can see in the diagram below, an MOV forms a connection between the hot power line and the grounding line. An MOV has three parts: a piece of metal oxide material in the middle,…

What is circuit protector?

circuit protection. [′sər·kət prə′tek·shən] (electronics) Provision for automatically preventing excess or dangerous temperatures in a conductor and limiting the amount of energy liberated when an electrical failure occurs.

What is a MOV circuit?

A metal oxide varistor (MOV) is a device used as a component in electrical equipment. The word varistor is short for variable resistor. A resistor is a circuit that does not conduct electricity well. This is useful for controlling how much electric current travels to certain parts of electronic devices.

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