A controllable reactor is connected in series in the stator circuit of the three-phase asynchronous motor. During the start and stop of the asynchronous motor, the AC contactor is disconnected, and the starting current of the motor is controlled by the solenoid valve type controllable reactor device; During the normal operation of the motor, the AC contactor pulls in, and the three-phase AC power is directly added to the stator winding. The strength change of the current limiting effect of the reactor is realized by controlling the DC excitation current and changing the saturation of the iron core, so it is called the soft start of the magnetic control motor.
When the three-phase asynchronous motor is directly started, the three-phase alternating current is directly added to the short-circuit impedance. When the controllable reactor is connected in series on the stator side to start, it can be understood as increasing the value of the stator side reactance, or it can be understood as reducing the actual voltage applied to the stator, the purpose of which is to reduce the starting current.
Obviously, the starting of the stator string controllable reactor can significantly reduce the starting current of the motor, which is more suitable for no-load and light-load starting, as well as pump and fan load starting. When starting, the reactor is connected with the maximum inductance value, and then the conduction angle of the thyristor is changed to adjust the capacity of the controllable reactor smoothly and continuously. The climbing curve starts smoothly, and the electromagnetic torque rises rapidly, which shortens the starting time of the motor.
The iron core magnetic circuit of the solenoid valve type controllable reactor is connected in series with a large-area section and a small-area section. In the entire capacity adjustment range of the controllable reactor, the iron core of the large-area section is always in the unsaturated linear region of magnetism, and the magnetic resistance is negligible relative to the small-section section; the magnetic saturation of the small-area section can be designed to be close to the limit value. At this time, the harmonics generated by the controllable reactor are very small, about half of the harmonics generated by the thyristor-controlled reactor.
The volt-ampere characteristic of the solenoid valve type controllable reactor is approximately linear, so it can effectively eliminate the parameter oscillation phenomenon that may occur during its operation. The output current (capacity) of the controllable reactor increases with the increase of the conduction angle, and the current transition time from no-load to rated or from rated to no-load capacity is about 0.3s.
Compared with the magnetic saturation soft-start devices currently on the market, although the DC control current is used to control the saturation of the iron core to smoothly and continuously adjust the reactance value, the former uses the grid voltage itself through the winding autotransformation, and the thyristor is used. The components are rectified to obtain power without external excitation, but the latter requires a separate DC control power supply; the former organically combines the working winding and the control winding, which is conducive to reducing losses and simplifying the structure, while the working winding and control winding of the latter However, they are separate; the former has a reduced section of the iron core. In the
Tel/Fax: 0086-577-62840011
WhatsApp: 008613355775769
#softstarter #motorsoftstar #softstarters #softstartechnology #ZJSHUYI
#softstartermarket #softstarterprice #threephaseforacmotor
#builtinbypasssoftstarter #singlephasemotorsoftstarter