FNR 14K561 Brand New High Quality Zinc Oxide Varistor

FNR 14K561 Zinc Oxide Varistor – Surge Protection for Mining PSU Input Stage

The FNR 14K561 is a zinc oxide metal-oxide varistor (MOV) providing surge protection on the AC input stage of mining power supplies. Its nonlinear resistance characteristic clamps voltage spikes — from lightning, load switching or grid disturbances — before they reach the PSU's primary electronics. The zinc oxide ceramic construction provides fast response and high energy absorption capacity per surge event.

Why Varistors Fail in Mining PSUs

Varistors are sacrificial protection devices. Each surge event degrades the MOV material slightly, shifting its clamping voltage downward over time. In mining environments with poor power quality — generators, overloaded grids, frequent on/off cycling — the varistor absorbs repeated transients until it begins conducting continuous leakage current, overheats and fails. Replacing the varistor restores input-side surge protection before the next event damages more expensive downstream components.

Replacement Procedure

Disconnect mains and open the PSU. Locate the varistor on the input filter board near the AC inlet — a disc-shaped radial component. Desolder both leads, remove, install the new FNR 14K561 observing the same lead spacing. Solder, reassemble and verify normal PSU startup. If the input fuse also blew, replace it before powering up.

FNR 14K561 Varistor Specifications

Related Varistors & PSU Surge Protection

• TVR14511 Varistor – APW12 PSU Repair
• 14D681K Varistor – Avalon PSU3300-03
• S14K300 MOV – APW9 PSU Repair
• TVR14471KSY 470V Varistor – Surge Protection

Repairing PSU input protection? Contact us at contact@lys-sz.com for varistors, thermistors and fuses.

Worldwide shipping from our Shenzhen warehouse.