Single chip microcomputer STM32L151CCU6

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

Mobile phone crystal 3.2*2.5mm 3225 26M (26.000MHZ)

100V, 250mA, surface mount, high speed switching diode

SMD aluminum electrolytic capacitor

According to the capacity of the three-phase squirrel cage asynchronous motor, the calculation method for selecting the open, contactor, thermal element and wire is as follows:
1. When the capacity of the motor is set to N KW, the rated current of the motor is: 2N A. Under normal circumstances, it is almost the same as the rated current on the motor nameplate! If you don't believe it, you can check it with the motor manual. This formula can be said to be very accurate!
For example: motor power 7.5KW, the rated current is 15A ;
When the motor power is 55 KW, the rated current is 110A ;
The rated current is the most important basis for selecting the open, contactor and wire!
2. Choose to open as follows:
When the capacity of the motor is set to N KW, the rated current of the motor is: 2N A. In general, the capacity to select the open air is about 4N A;
For example: motor power 7.5KW, the rated current is 15A The open capacity should be 32 A ;
When the motor power is 55 KW, the rated current is 110A The open capacity should be 250 A ;
Note: The air blower and pump type of the fan and pump are selected to be larger because they have a longer starting time and a larger starting torque.
3, the contactor is selected as above, ie (3.5-4) NA;
4, wire selection: according to the rated current of the motor to choose, generally 1.5 times the rated current, but to consider the laying environment, laying methods, etc., multiplied by the appropriate coefficient.