Noker Ac Drives 10kV 1000kW Medium Voltage Vfd Motor Soft Starters

The high voltage motor soft starter with many start ways: current current-limiting starting, voltage ramp + current limit flow , jog, kick + voltage ramp startup mode etc, A variety of parking: parking free and parking soft. The user can choose according to difference of load and the specific conditions of use different ways of start and stop.
1.Current limiting current soft start
According to the "current-limiting magnification" Settings, after the soft starter to get Start the instruction, the output voltage rapid increase and the current increases. While the soft starter detecting the output current, and adjust the output voltage, until the output current reaches the set current limiting value.at this time the output current no longer increases, the current began to decline after motor speed for some time, the output voltage the rapid increase until the total output, then input the bypass contactor, the start process is completed. Startup current changes as shown on the right. Under current limiter method, the actual start time is associated with multiple current limit and the load. Current limiting characteristics can make the large inertia load with minimum current start, acceleration, and suitable for many of the constant torque load started, ensure that the situations of the limited power grid capacity.

2.Voltage ramp + current limit flow
Starting from the initial voltage， output voltage according to set the "start time by the index properties of rise . at the same time, output current at a certain rate increase until the Start process finished. Current in the process of start is limited in the "current limit flow ratio" below. Start the process of voltage, current changes such as shown in the picture on the right. In a ramp voltage limiter startup mode, the actual start time is related to current limiting ratio, load, initial start-up voltage, the startup time set. This way has the early start current is small, the advantages of the maximum current controlled, suitable for grid limited capacity under pump load startup, fan etc.

3. Jog
Press start button to start jog, the out voltage increased to the set voltage as the fixed rate, press the stop button to end jog. After the start, the output voltage is constant value (" the jog voltage setting values), motor rotated under the voltage. Jog mode is mainly used for debugging stage.

4.Kick + voltage ramp
In order to overcome the bigger of the two static friction, in the initial stages of start to large pulse torque load motor, its amplitude and time by the parameter "step voltage" and "sudden jump time" decision, and then according to the voltage ramp start way start motor.

5.Free stop
Soft starting device after receiving halt instruction, the first block of bypass contactor control relay and immediately sealed off the main circuit of thyristor output, load inertia motor free downtime.

6.Soft stop
When soft stop time is not set to zero, in a Full voltage state of parking is soft parking, stop on this way, the soft starter first disconnect bypass contactor, soft starter of the output voltage as the setting of the soft parking time gradually reduced until to zero. In the process of parking voltage curve as pictured. Voltage slope soft parking characteristics can effectively reduce the reverse impact torque, is often used to alleviate the water hammer in pump load effect.