1 General DNH5 series bar and fuse type isolating switch is applicable in the circuit of rated voltage AC 660V and below, rated current AC160A-630A, rated frequency of 50Hz. In the power distribution system of industrial enterprises, it is mainly used in distributor circuit and motor circuit with high short-circuit current for infrequency manual making, breaking and disconnecting the power supply. However, it is not suitable for starting and breaking of single motor. This product is according with the Standard of GB14048.3-2002, IEC947-3(1999). 2 Normal working and installation conditions 2.1 ambient temperature:-5 ^oC~+40^oC, the average temperature shall not exceed 35^oC in 24 hours. 2.2 Altitude: Shall not exceed 2000m. 2.3 Pollution condition: Grade3 2.4 Humidity: The relative humidity shall not exceed 50%when the environmental temperature is +40^oC in installing place: And the relative humidity may be higher at the lower temperature condition, The maximum humidity can up to 90% at +20^oC 2.5 The product shall be installed in the place without rain and snow, without remarkable shake and quiver. 2.6 The switch shall be installed vertically. 3 Structure and feature The switch is consisted of underpan, base, cover, handle and shield. NT series fuse link is installed in the cover to act as knife of active contact: the handle moves fan-shapely based on the pivot of underpan, makes the cover and fuse make and break together, it is with enough space and remarkable disconnection point which meets the requirement of isolating switch. And it is convenient to dismount the base and underpan, which is easy to mount the base to the busbar safely and reliably. There is arc extinguisher on the underpan, which ensures breaking capability of the switch.