9065CT9701R03/21

Melting Alloy Overload Relays

In melting alloy overload relays, the motor current passes through a small heater winding. The heater is combined with a solder pot in a one-piece, nontamperable thermal unit. During overload conditions, the heater causes the special solder to melt, allowing a ratchet wheel to spin free. This action opens the control circuit contacts, and the overload relay trips.

Melting alloy thermal overload relays must be reset manually after they trip. A reset button is usually mounted on the cover of enclosed starters.

Thermal units (heaters) are rated in amperes and are selected on the basis of motor full-load current, not horsepower. To obtain the appropriate tripping current for motors of different sizes, or different full-load currents, a range of thermal units is available.

Melting Alloy Thermal Unit

QR Code is a registered trademark of DENSO WAVE INCORPORATED in Japan and other countries.

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