Kraus & Naimer KG251 Disconnect Switch

The Kraus & Naimer KG251 is a disconnect switch engineered for reliable isolation of electrical circuits in industrial settings. Rated for 250 A at 690 V nominal, it accommodates both 3-pole and 4-pole configurations and handles motor loads across utilization categories AC-3 and AC-23A. The switch provides forced opening and closing of main contacts, substantial creepage and clearance distances between terminals, and terminal shrouding on models rated 80 A to 250 A for simplified field wiring. ## Technical Specifications • Rated Thermal Current: 250 A (Iu/Ith and Ithe) • Rated Uninterrupted Current: 250 A • Nominal Voltage: 690 V • Rated Insulation Voltage: 600 V AC • Rated Impulse Withstand Voltage: 8 kV (Overvoltage Category III, Pollution Degree 3) • Rated Short-Time Withstand Current: 4600 A for 1 second • Maximum Fuse Rating: 250 A (gG characteristic) • Power Loss per Pole: 8 W • Poles: 3-pole and 4-pole models available • Auxiliary Contacts: Optional 2NO/2NC configurations ## Rated Operational Current • AC-20A: 250 A • AC-21A: 250 A at 20–690 V • AC-22A: 200 A at 220–500 V; 125 A at 660–690 V ## Motor Switching Power (AC-3 / AC-23A) • AC-3: 37 kW to 75 kW depending on voltage and phase configuration • AC-23A: 45 kW to 110 kW depending on voltage and phase configuration ## Key Features • Forced contact operation for main contacts • High dimensional clearance enabling straight-line terminal wiring • Terminal shrouds supplied on 80 A–250 A models • Screw or ring terminal options with specified torque requirements (16 Nm for M12) • IP65 enclosure protection on panel-mount variants ## Typical Applications • Main or maintenance isolation for machine tools • Distribution panels and switchboards • Motor load switching and starting circuits • Mixed resistive and inductive load control ## Compatibility & Integration Valid for grounded common neutral termination supply systems. Ring cable lug dimensions: 25.00 mm and 34.00 mm terminals. Panel-mount configurations supported.