The product is to service at the control circuit of the crane of AC 50~60Hz, AC380V, DC220V and current of 10A to serve as terminal protection of mechanism travel. The nominal service conditions include an ambient temperature of-30℃∽+40℃, ambient relative humidity of 85%, altitude of 1000m and protection degree of IP44. It complies with the standard of IEC337-1 and GB14048.5-2001.