AC overvoltage protection circuit

1. A power converter for operation from an AC power source, comprising:

a bridge rectifier having an input to receive an AC input voltage and an output to provide a DC voltage, the AC input voltage received from the AC power source through a fuse;

a relay having a relay coil and normally open contacts, the normally open contacts connected across the AC input voltage; and

one or more zener diodes in series connection with the relay coil, the series connection of the one or more zener diodes and the relay coil connected across the DC voltage, wherein

the one or more zener diodes and the relay coil are configured such that the normally open contacts are closed to cause a short circuit across the AC input voltage when the DC voltage exceeds a predetermined voltage value for a predetermined period of time.

2. The power converter of claim 1 , wherein the relay is configured to maintain the short circuit across the AC input voltage until the fuse opens.

3. The power converter of claim 1 , wherein the predetermined period of time is equal to an actuation response time of the relay.

4. The power converter of claim 1 , further comprising:

a capacitor to filter the DC voltage, wherein

the predetermined voltage is less than a voltage that causes a hazardous failure of the capacitor.

5. The power converter of claim 4 , wherein

the capacitor is an electrolytic capacitor, and

the predetermined voltage is less than a voltage that causes venting of liquid electrolyte from the electrolytic capacitor.