The N-frame OPTIM Series C circuit breaker (Figure 1-1) types ND, HND, and NDC are 600 VAC maximum rated devices with Digitrip OPTIM Models 550, 750 or 1050 trip units rated 800A or maximum continuous current. They are for AC applications only and can be reverse fed. They are listed in accordance with Underwriters Laboratories, Inc. Standard UL 489 and satisfy the requirements of International Electrotechnical Commission Recommendations No. IEC OPTIM 750 and 1050 N-Frame circuit breakers are equipped with zone interlocking and an auxiliary switch and alarm switch for customer usage. Other internal accessories are available but must be factory installed since they are factory sealed. Model 550 is not sealed and can accommodate field installed accessories, including an communications kit. Agency advantages supply the following brands: ①Allen-Bradley( Rockwell Automation)Series ②Square D（Schneider Electric） Series ③Eaton - Cutler Hammer (Westinghouse )Series ④SIEMENS PLC Series，Siemens CNC system ⑤Eaton moller Series