Working principle
Voltage ramp start mode: In the early stage of the soft start cabinet, by controlling power electronic devices such as thyristors, the output voltage rises slowly according to the preset ramp curve, gradually increasing from the lower voltage to the rated voltage of the motor. The motor current also gradually increases, avoiding the sharp rise of the current during direct start, thereby reducing the impact on the power grid and the motor itself.
Limit viewership of start mode: set a limit viewership of value, in the start process, the soft start cabinet real-time monitoring of motor current, when the current reaches the limit viewership of the value, by controlling the conduction angle of the thyristor, limiting the further increase of current, so that the motor does not exceed the set limit viewership of the case where the value of gradually accelerating start, until the rated speed.
product structure
Power cabinet: As the shell of the entire soft-start cabinet, it protects the internal electrical components and provides installation support. The protection level can be selected according to the use environment. The common ones are IP40, etc. It is generally made of cold-rolled steel plate or aluminum-zinc-coated steel plate, which has good strength and corrosion resistance.
Bypass soft starter: It is the core control component of the soft start cabinet. It usually uses thyristors or other power electronic devices as switching components to adjust the output voltage and current by controlling its conduction angle to achieve the soft start function of the motor. Its power should be selected according to the power of the driven motor. For a 37kW motor, a soft starter with corresponding power or slightly higher power is generally selected.
Bypass contactor: After the motor is started, the soft starter is short-circuited, allowing the motor to be directly connected to the power grid for operation, reducing the loss and heat generation of the soft starter, and improving the efficiency and reliability of the system.
Voltmeter and ammeter: used to monitor the voltage and current values during the operation of the motor in real time, so that the operator can understand the operation status of the motor and detect abnormal situations in time.
Molded case circuit breaker: plays the role of overload, short circuit and undervoltage protection in the circuit, and can automatically cut off the circuit when overload, short circuit or undervoltage faults occur in the circuit to protect the safety of motors and other electrical equipment.
Current transformer: used to measure the running current of the motor, convert large currents into small current signals, so as to facilitate the measurement and display of the ammeter, and also provide signal input for the current detection and protection functions of the soft starter.
Control circuit and other accessories: including control buttons, indicator lights, knobs, relays, fuses, etc., used to realize manual/automatic motor control, status indication, fault alarm and other functions.
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