There are many ways to start the pump, such as direct start, star triangle start or buck start. The starting method of these three control cabinets is relatively cheap, and if the frequency conversion is selected, the cost will be relatively high. Today we are talking about the soft start of the pump.
The pump soft starter is a novel motor control device that integrates motor soft start, soft stop, light load energy saving and various protection functions. It is called SoftStarter in foreign countries. Its main component is a three-phase parallel thyristor connected in series between the power source and the controlled motor and its electronic control circuit. Different methods are used to control the conduction angle of the three opposite parallel thyristors, so that the input voltage of the controlled motor changes according to different requirements, and different functions can be realized. Soft starters and frequency converters are two completely different applications.
The frequency converter is used for speed regulation. The output not only changes the voltage but also changes the frequency. The soft starter is actually a voltage regulator. When the motor starts, the output only changes the voltage and does not change the frequency. The frequency converter has all the soft starter functions, but it is much more expensive than the soft starter and the structure is much more complicated. The motor soft starter uses a soft starter connected in series between the power supply and the controlled motor to control the conduction angle of the internal thyristor, so that the input voltage of the motor gradually rises from zero with a preset function relationship until the end of the start, and the motor is given to the motor.
The full voltage, that is, the soft start, during the soft start process, the motor starting torque is gradually increased, and the rotational speed is gradually increased. When the function of the pump soft starter is directly activated, the current may reach 6-7 times of the rated current, which will cause problems for other power-consuming equipment in the factory. When using soft start, the starting current is about 2-3 times of the rated current. For the pump, there is also a soft stop to allow the water to slowly fall back and eliminate the water hammer effect. Simply put, it is slowly started and slowly stopped. This slow time can be adjusted, about 1-60 seconds.
