Why can the motor start only when the soft starter is reset?

- Dec 26, 2019-

The first thing to understand is "reset."In the electronic circuit, in order to make the microcomputer or single-chip microcomputer can work normally (including the sequential digital circuit, clock signal circuit), when there are other problems in the process of operation, to restore its original state (or known as the initial state), there is a manual reset open key.

It works, on the RST pin of integrated circuit and integrated circuit of power supply between Vcc access a normally open button, when the fault occurs later generations to press a button, the voltage Vcc voltage directly to the RST side, the digital circuit caused by failure to release before stop vibration phenomenon, restores the initialization state to start work again.The next step is to understand the construction of the soft starter.

The soft starter USES a 16-bit single-chip microcomputer as the core and many signal acquisition sensors to control the motor intelligently.It can conduct stepless voltage regulation to the optimal starting current required by the motor.Simply put, it is an alternative to the traditional Y/△ step-down startup device.Soft starter with the help of single-chip microcomputer for all-round control, it usually has the following functions;

(1) self-test function.After the soft starter is powered on, the internal system will conduct self-inspection. If there is any fault, it will immediately alarm.

(2) set the rated current.It is matched with the rating of the supporting motor, once the rated current of the soft starter is determined, the tripping level of the electronic overload protector is also determined.Soft start function.When it receives the start command, it will automatically enter the start program and output a linearly rising voltage to the motor within a specified time (generally between 0.5 and 60s).

The initial starting voltage is 10%~60% of the rated voltage of the motor, and the voltage after starting is the rated voltage of the motor.Before starting the operation, the size of the starting voltage can be set on the operation panelSet, including startup time).

Medium and large motors need to start energy saving, and consider the initial investment situation, the power of the motor below 75KW using self-coupling voltage reduction Y/△ start more economic.It is more economical to use a soft starter for motors of 75~250KW.In the case of self-willed economic conditions, we can directly choose the frequency converter to start the motor with variable frequency and reduced voltage.In general, the voltage drop is less than 10%Ue, which must be paid attention to in the use process.

Many protection functions are set in the soft starter, including energy saving function, overheating protection function, bidirectional thyristor damage protection function, missing phase protection function and so on.After any problem occurs in any link, its corresponding sensor will timely feedback the fault situation to the single-chip chip, and the chip will issue instructions to automatically stop the work of the circuit.

Under normal circumstances, the alarm signal sent by it has the corresponding fault code. The purpose of this is to let the operator to correct the fault code according to the instructions and restart the work in a timely manner.Failure is not eliminated, not reset, it will always be stopped to ensure the safety of the motor.