Thyristor is the most critical power device in motor soft starters, switch cabinets, etc. Whether the whole device works reliably has a great relationship with the correct selection of thyristor rated current, rated voltage and other parameters.

The principle of selection should first consider the reliability of work, that is, the current and voltage must have sufficient margin multiples. Secondly, the economy, that is, the price/performance ratio, should be considered, and finally, the installation should be beautiful, and the volume should be minimized.

For 6kv, 10kv high-voltage motors, due to the high voltage, it is necessary to connect the thyristors in anti-parallel and then in series. Each phase of 6kv requires 6 thyristors (2 anti-parallel, 3 groups in series), 10kv each phase requires 10 thyristors (2 anti-parallel, 5 groups in series). In this way, the voltage that each thyristor bears is about 2000v, so the forward and reverse non-repetitive rated voltage vdsm.vrsm of the selected thyristor should be above 6500v.

For the selection of the rated current of the thyristor, the rated working current of the motor must be considered. Generally speaking, the current of the thyristor should be 3~4 times of the rated current of the motor. In the soft starter of the thyristor high-voltage motor, an AC phase-controlled voltage regulation composed of two independent thyristor devices is used in reverse wells, and the positive and negative half cycles correspond to 1 The two thyristors work, so the consistency of the parameters of the two reverse well-connected devices is relatively high. Including the thyristor trigger parameters, the maintenance current parameters, etc. are also required to be selected as consistent as possible. Try to make the positive and negative half-wave symmetrical, otherwise there will be a DC component current. Flow through the motor. Since the motor is inductive for the winding load, the excessively high DC content will cause the motor stator to heat up seriously, and even burn the motor windings, thus making the motor scrapped. Should be above 6500v.

For the selection of the rated current of the thyristor, the rated working current of the motor must be considered. Generally speaking, the current of the thyristor should be 3~4 times of the rated current of the motor. In the soft starter of the thyristor high-voltage motor, an AC phase-controlled voltage regulation composed of two independent thyristor devices is used in reverse wells, and the positive and negative half cycles correspond to 1 The two thyristors work, so the consistency of the parameters of the two reverse well-connected devices is relatively high. Including the thyristor trigger parameters, the maintenance current parameters, etc. are also required to be selected as consistent as possible. Try to make the positive and negative half-wave symmetrical, otherwise there will be a DC component current. Flow through the motor. Since the motor is inductive for the winding load, the excessively high DC content will cause the motor stator to heat up seriously, and even burn the motor windings, thus making the motor scrapped.