JB 8591.1-1997 This standard complies with the requirements of GB 14048.4-1993 "Low-voltage starting equipment and control equipment low-voltage electromechanical contactors and motor starters". This standard specifies the general basic rules and requirements for CJ20 series AC contactors (hereinafter referred to as contactors), including: terminology, characteristics, normal operating and installation conditions, structural and performance requirements, verification of characteristics and performance, etc. This standard applies to contactors with AC 50Hz, rated voltage 660V (1140V), and current up to 630A. Contactors are mainly used to frequently connect and break circuits over long distances, and are combined with appropriate thermal relays or electronic protection devices to form motor starters to protect circuits that may be overloaded.