In HYDRAN M2 medium- and high-voltage motor solid-state soft starting device [3], the weak part adopts DSP as the control chip, microcontroller as the management chip, and SPC3 as the communication chip; the high-voltage part consists of several groups of series/parallel thyristors, vacuum contactors, voltage transformers and current transformers. The PWM trigger pulse generated in the DSP is triggered by the optical fibre through the energy storage tube and short-circuit transformer to realize the triggering of the thyristor by the pulse transformer on the high-voltage side; in order to ensure that multiple groups of thyristors (a pair of anti-parallel thyristors connected in series) in each phase are balanced in terms of voltage distribution, each group of thyristors is connected in parallel with a set of dynamic and static equalization boards.

When the HYDRAN M2 soft starter starts, the controller DSP controls the vacuum contactor to turn on, and by controlling the conduction angle of the SCR, it makes the motor gradually increase the voltage according to a certain slope, and start smoothly; when it reaches the rated speed, it adds the full voltage, and at the same time, the bypass vacuum contactor is turned on, and then it turns off the trigger signal of the SCR and stops the power supply of the SCR. Motor starting is completed. After that, the soft starter continues to monitor the running status of the motor and provides a variety of fault protection. Its applicable objects are mainly the control and protection of starting, running and stopping of squirrel-cage asynchronous medium- and high-voltage motors.

HYDRAN M2 Its loads are mainly fans, centrifugal pumps, air compressors, belt conveyors, crushers, mixers and so on. The starting, running and stopping of the soft starter can be controlled and displayed by the upper computer through the PROFIBUS-DP bus, in which the medium- and high-voltage solid-state soft starter participates in the system configuration as an intelligent slave. The initialisation procedure mainly includes [4]: setting the interrupts allowed by SPC3, the slave address identification number, the mode register, the diagnostic buffer, the parameter buffer, the configuration buffer, the address buffer, the PRM telegrams, the CFG telegrams, the SSA telegrams, the initialisation data length, the initialisation user data length, setting the input and output buffer pointers, the diagnostic buffer pointer, the CFG buffer pointer, PRM buffer pointer, etc.