The start mode of the soft starter mainly includes: current limit start mode, voltage ramp start mode, kick mode, current ramp start, voltage limit current double closed loop start.
1 current limit start mode, start process: When the motor starts, the output voltage increases rapidly until the motor current reaches the set current limit value, and keeps the motor current not greater than the set current limit value, and then The output voltage gradually rises and the motor gradually accelerates. When the motor reaches the rated speed, the bypass contactor pulls in, the output current drops rapidly to the rated current of the motor or below, and the startup process is completed.
When the motor load is light or the set current limit value is large, the maximum current that can be started may not reach the set current limit value. The current limit mode is generally used in applications where the starting current is strictly limited.
2 Voltage harmonic start: When the motor starts, if the motor current does not exceed 4 times of the rated value, the soft start output voltage rises rapidly to the starting voltage value at startup, and then the output voltage gradually rises according to the set starting parameter. The motor continuously accelerates smoothly with the rise of the voltage. When the voltage reaches the rated voltage, the motor reaches the rated speed, the bypass contactor pulls in, and the starting process is completed.
In general, the voltage ramp start mode is suitable for applications where the startup current is not critical and the start stability is high.
3 Kick mode: In some heavy-duty situations, this mode can be selected due to the influence of mechanical friction and the motor cannot be started. At start-up, a higher fixed voltage is applied to the motor for a limited period of time to overcome the static friction of the motor load to cause the motor to rotate and then start by limiting current or fixed voltage ramp.
Before using this mode, the motor should be started in non-bump mode. If the motor cannot be rotated due to too much static friction, select this mode. Otherwise, avoid using this mode to reduce unnecessary high current surge.
4 current ramp start mode; this mode has a strong acceleration capability, suitable for two-stage motors, can shorten the start-up time within a certain range.
5 voltage current limiting double closed loop start
The voltage ramp and the current limiting double closed loop control are a comprehensive starting mode that requires smooth starting and strict current limiting, and a prediction algorithm for estimating the working state of the motor is adopted.
The voltage waveform output from this mode will vary depending on the motor and load conditions.