20D391K MOV Varistor 390V

20D391K MOV varistor (390V), also known as VDR-20D391K, is engineered for surge protection in low to medium voltage AC power systems where stable clamping performance and high reliability are required.

It is typically applied in 220V–250VAC power lines, providing effective protection against transient overvoltage caused by lightning strikes, switching operations and grid disturbances.

Compared with lower voltage MOVs, 20D391K offers a higher operating margin, making it suitable for applications requiring improved surge tolerance and long-term durability.

The 20mm disc construction enables strong surge current handling capability, making it ideal for repeated surge environments.

Key Electrical Characteristics:

Varistor Voltage (1mA): 390V ±10%  

Maximum Continuous Voltage: 250VAC / 320VDC  

Maximum Clamping Voltage: approx. 650V  

Peak Surge Current (8/20μs): 8kA  

Maximum Energy (2ms): 150J  

Capacitance (1kHz): approx. 750pF  

Application Focus:

AC mains surge protection  

Switching power supplies  

Industrial control systems  

Home appliances and consumer electronics  

Power adapters and chargers  

Design Tips:

- Choose MOV voltage based on AC mains level (220V–250VAC systems)  

- Ensure adequate surge current rating for long-term operation  

- Consider coordination with fuse or thermal protection device  

Related MOV Varistor Models:

20D361K MOV Varistor 

20D561K MOV Varistor

20D621K MOV Varistor

20D Series 20mm MOV Varistors

Replacement and Cross Reference

S20K250 (TDK EPCOS)  

B72220S0251K101 (TDK EPCOS)  

All trademarks and part numbers mentioned are for reference only.

For datasheet, quotation or sample request:

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