Knife switch is also known as knife switch or isolation switch, it is the most simple and widely used low voltage electrical appliance in manual control. So, how to choose the board knife switch? The following is an introduction to the selection of panel knife switch:
1. Selection of structural forms
Its structure is determined according to its function in the line and its installation position in the distribution set. When only used to isolate the power supply, only use the product without the arc extinguishing cover. If it is used to break off the load, the product with an arc extinguishing cover should be selected and operated by means of a lever. If the central handle knife switch cannot cut off the load current, other forms can cut off a certain load current, but must choose the knife switch with the arc extinguishing cover. In addition, still answer a root to be opposite operation or side operation, it is direct operation or lever drive, it is board before wiring or board after wiring to choose structural form.
HD11 and HS11 are used in magnetic stations. They do not cut off the circuit with load and are only used for isolating current.
HD12 and HS12 are used for front side operation of the front maintenance switch cabinet, where the tool switch with the arc extinguishing device can cut off the load circuit below the rated current.
HD13 and HS13 are used in the switch cabinet for maintenance after front operation, in which the knife switch with arc extinguishing device can cut off the load circuit below the rated current.
HD14 is used in power distribution box, in which tool switch with arc extinguishing device can operate with load.
2. Selection of rated current
The rated current of knife switch should not be less than the sum of the rated current of each load in the closed circuit. If the load is a motor, it must be considered whether the maximum short circuit peak current in the circuit is below the peak electric stability current corresponding to the rated current level.
When short circuit accident, if the knife switch can pass with a maximum short-circuit current, is not produced because of its huge electric effect and produce the deformation, damage or touch the knife automatically pop up phenomenon, is a short-circuit current peak peak current is the electric knife switch stability. In case of exceeding the rated current, a knife switch with a higher rated current should be selected.
