MOV-20D201K 20ohm 4A 20mm Radial Leaded Varistor - Avalon PSU

MOV-20D201K Metal-Oxide Varistor | 20mm Radial-Leaded Surge Suppressor for Avalon Miner PSU

The MOV-20D201K is a 20mm radial-leaded metal-oxide varistor (MOV) used on Avalon Miner power supplies for AC-line surge protection. Defends downstream PSU circuitry against transient overvoltages — lightning strikes, power contact events, and inductive transients on the mains supply. Fast response time, high energy absorption, low clamping ratio, and no freewheeling current after clamp release.

Drop-in replacement when the original sacrifices itself absorbing a surge (its job) or degrades from years of mains transients. The 20mm disc has higher energy capacity than the smaller 14mm class — better for the Avalon PSU input stage where surge tolerance matters across multi-kW switching.

When to Replace the MOV-20D201K

• PSU dead after a known voltage event — surge, lightning, utility transient — varistor often sacrifices itself and shorts to protect downstream circuitry.
• Input fuse blown with no other visible damage — varistor shorted, took out the fuse on the next surge.
• Visible cracking, blackening, or charring on the disc body or epoxy coating.
• Burn marks on the PCB around the varistor footprint after a fault event.
• Preventive replacement on Avalon PSUs returning from sites with poor mains quality.

MOV-20D201K Specifications

FAQ — MOV-20D201K Varistor

Q: Why does the varistor short when it absorbs a surge?
A: That's its design behaviour — a MOV clamps overvoltage by conducting the surge to neutral. Big surges fuse the internal granular structure into a low-impedance path, sacrificing the part to save the rest of the PSU. Always replace a sacrificed varistor along with the input fuse.

Q: 20mm vs 14mm MOV — does the size matter?
A: Yes — disc diameter sets the energy capacity. The 20mm class handles higher single-event energy than the 14mm equivalent. For the Avalon PSU input stage, stick with 20mm — substituting smaller risks under-rated protection.

Q: How do I test if the existing varistor is still healthy?
A: Power off and isolated, measure resistance across the leads with a high-range DMM. Healthy MOV reads OL (megohms+). Shorted or partially-conducting reading = degraded varistor, replace.

Q: Bulk pricing for Avalon PSU repair benches?
A: Yes — email contact@lys-sz.com for volume pricing on MOV-20D201K plus matched input fuses for Avalon PSU repair kits.

Related products

• 14D681K Varistor (Avalon PSU3300-03)
• S14K300 Varistor (Bitmain APW9)
• TVR 14511 Varistor (Bitmain APW12)
• Avalon PSU3300-03 Plus (A1066 / A1166 / A1246)

Avalon PSU repair benches stocking MOV-20D201K varistors by the strip? Email contact@lys-sz.com for bulk pricing. Worldwide shipping from our Shenzhen warehouse.