Iron shell fuse type load switch HH12D-20/3

型号：

HH12D-20/3

电流：

20A

种类：

铁壳开关

The official name of the iron shell fuse type load switch/3 is a closed load switch or a fuse type load switch. It is a casing made of steel plate or cast iron, equipped with a fuse for cutting off short-circuit current, a knife switch for connecting and breaking the circuit, and an operating mechanism for operating the knife switch. It can therefore be manually operated for infrequent making and breaking of circuits and for short-circuit protection. Iron shell fuse type load switch/3 is widely used in electrical installations in industrial and mining enterprises, electric heating lighting and rural power drainage and irrigation, and can be used for infrequent direct starting and stopping of small induction motors.
The fuse installed in iron shell fuse type load switch/3 has a relatively low ultimate breaking capacity (generally type R), so it should be installed at the end of the line where the short-circuit current is not large, otherwise it will act as an iron fuse. When a short circuit occurs in the circuit below the shell switch, the short-circuit current exceeds the breaking capacity of the fuse, and the fuse will explode, exacerbating the accident.
The knife switch of the iron shell fuse type load switch/3 is equipped with an energy-storage operating mechanism, which allows the knife to quickly open and close. An arc extinguishing cover is also installed on the contact, so the switching capacity is improved. And because it is protected by an iron shell, it is not easy to cause arc light accidents that can cause injuries when switching on and off.
When the iron case fuse type load switch/3 is used to directly start and stop small induction motors infrequently, it is generally recommended to control motors below 300 kW. It is also used to control motors below 100 kW. This is because most users have gained a lot of experience in controlling motors below 3.0 liters. When used to control motors above . It is easy to break, which often causes the motor to run out of phase. Therefore, the capacity of the iron-cased fuse-type load switch/3 direct-start motor should not be used too much. From the comparison of technical and economic indicators, the iron-cased switch is only used for It is more economical to start the motor directly than to automatically shut down the motor below .
In general electric heating and lighting circuits, iron-clad switches can be selected according to the rated current of the load. When used to control the full-voltage starting of a squirrel-cage asynchronous motor, it is necessary to consider the possibility of using an iron-cased fuse type load switch/3 to cut off the circuit when the motor is blocked, so the iron-cased switch must cut off the starting current of the motor, which is twice the rated value. current. When controlling the motor, choose the iron case switch according to this principle. For example, the rated current of an electric motor is...