About the K-51
K-51 is a Reliance Electric Voltage Relay. It is a small black square with two screws to attach it and two prongs that protrude out of the side. The K-51 is interchangeable for the 63807 (all symbols), the 63807-1 (all symbols), and the 69331 (all symbols). As a multi-voltage relay, this device can function is a wide range from 24 to 240 VAC and 24-240 VDC with a wide frequency range like 0 to 300Hz. These are meant to be used in areas that don’t have a steady voltage supply that is stable. Refer to manuals from Reliance Electric for intricate details.
