Metal Oxide Varistor · 390 V varistor voltage 20 mm disc 6.5 kA surge · Through-hole MOV · Bourns MOV-20D391K
Bourns MOV-20D391K is a 20 mm through-hole metal oxide varistor with 390 V varistor voltage, 250 VAC maximum continuous rating, 320 VDC maximum continuous rating, and 6.5 kA surge current capability. Commonly used for equipment-level surge suppression on power input stages, control boards, and panel assemblies where a disc MOV is specified.
What this product is for
This metal oxide varistor (MOV) is used to clamp transient overvoltage events and help protect electronic circuits and equipment power inputs from short-duration surges. It is a through-hole 20 mm disc component commonly selected for OEM assemblies, repair work, and replacement on boards designed around a 390 V MOV.
Use for
Use for surge suppression on AC line input sections, control boards, power supplies, industrial electronics, and panel-mounted equipment where the design calls for a 250 VAC maximum continuous MOV with 390 V nominal varistor voltage. Typical applications include equipment-level protection used together with proper fusing and thermal protection.
Avoid for
Avoid using this part as a substitute where a different disc size, lead spacing, clamping level, energy rating, or agency-approved surge device is required. It is not a complete surge protective device on its own and should not be treated as a standalone panel SPD.
Best for
Best for technicians, panel builders, and electronics buyers who need a standard 20 mm through-hole MOV in the 20D391K class for board repair, maintenance stock, or original equipment builds.
Installed in
Typically installed on printed circuit boards, power entry sections, control assemblies, and enclosed equipment. The body is approximately 20 mm (about 0.79 in) diameter.
Why this product exists
This component exists to absorb short transient energy and reduce the voltage seen by downstream circuitry during surge events. As a rule of thumb, MOVs are commonly paired with upstream overcurrent protection because actual surge performance depends on installation conditions, source impedance, and the overall protection design.
Compared with similar products
Compared with smaller disc MOVs, a 20 mm MOV in this class is typically chosen when higher surge current and energy handling are needed. Compared with a complete DIN rail or panel surge protective device, this part is a board-level component intended for integration into equipment rather than finished service-entrance protection.
Specifications
- Manufacturer: Bourns
- Manufacturer part number: MOV-20D391K
- Product type: Metal oxide varistor
- Mounting: Through-hole
- Disc size: 20 mm (about 0.79 in)
- Varistor voltage: 390 V
- Varistor tolerance: +/-10%
- Maximum continuous voltage: 250 VAC / 320 VDC
- Maximum clamping voltage: 650 V
- Peak surge current: 6.5 kA
- Typical energy rating: approximately 180 J
- Typical capacitance: approximately 1000 pF
- Series: 20D
Estimated values such as energy and capacitance can vary by source listing and test method. Confirm the current manufacturer datasheet before final design-in.
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