It is often thought that the electric motor turns up as a success. But if the caused power grid pressure drop is too big, the occurrence of the other equipment due to undervoltage tripping, the running equipment blocking and so on, which is also unacceptable. Therefore, the definition of soft start success should be to complete the motor start within a set time frame, and the impact on other electrical equipment in the co-network is limited to the permitted limits.
First, the reason for the failure of the start-up
1, parameter setting problem
For example, for some of the motor's starting parameters to be mis-adjusted, such as, this problem only needto be modified under the parameters can be solved.
2, the load is too heavy
This problem is sometimes a problem with the design of the electrical drivetrain, for example, the motor capacity is too small and the drive torque is not sufficient to start the load. The treatment is done by replacing a larger motor, reducing the load or changing the starting mode, and another situation where the load is too heavy is the use of problems, such as forgetting to shut the door of the fan being driven.
3, the power grid pressure drop is too big
If the power supply capacity is too small, the line cable is too thin, then the pressure drop is too large when starting, the motor can not start naturally. The soft starter can only lower the voltage and does not increase the voltage. Consideration should be given to replacing a larger power transformer, using a larger cross-sectional cable, moving the power supply transformer near the motor load and other measures.
4, other electrical equipment and soft starting device is not suitable for the coordination
During the start-up process, equipment such as low-voltage short-circuit-recitals, fuses, thermal relays, etc. are tripped or fused. At this time, according to the system conditions, re-adjust the fixed value of electrical equipment or another configuration of suitable electrical equipment.
5, it may also be a non-suitable use of buck soft start applications
The congenital weakness of the buck soft starter is that the motor torque is proportional to the square of the motor voltage or current, after minimizing the load, the maximum starting current limited by the short-circuit capacity of the power grid cannot be used within the time limit of the motor load, so that the motor speed is raised to its rating.
Second, to ensure the conditions for the success of soft starting
1, to ensure that the electrical drive system design is correct, motor drive torque is sufficient.
2, the power grid capacity is sufficient to meet the soft starting conditions.
3, soft starting device and other electrical equipment with the correct, normal work.
4, soft starting device hardware and software reliability is tested. 5, the feasibility of soft starting of the motor buck.