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Permanent magnetic soft starter


Soft starter is the motor control equipment which integrates soft start, soft stop, light load energy-saving and multiple-function protection, realizing smooth motor starting without any impact in the whole starting progress. Various parameters can be adjusted during starting such as current limit and starting time according to load characteristics of the motor. Soft start under heavy load is always one of the problems of large-scale motor start. Resolving the problem is significantly helpful in a serious of problems faced with highly large-scale industrial production such as energy-saving motor selection, power grid protection, safe starting and running of the motor and dragging the load machine.

Jiangsu Magnet Valley Technologies Co., Ltd. is the first company in China which is engaged in applied research and development of permanent magnetic coupling soft starter. By utilizing non-contact and non-action clutch function of the winding permanent magnetic coupling soft starter, start the motor without any load first, and then start the load with the largest overload torque of motor (220% rated torque). That is a new concept of starting under heavy load. We adopt the most advanced permanent magnetic circuit technology and the newest motor manufacturing technology to achieve small structure and size but large transmission torque.

Ⅱ、System composition of permanent magnetic coupling soft starter

Ⅲ、Working principle and features

1、Working principle


2-shaft one

3-shell, forming the permanent magnetic outer rotor

4-iron core of winding rotor

5-coil winding

8-shaft two, forming the winding rotor

9-the air gap between p-m rotor and winding rotor

6-electric brush

7-collecting ring

When there is rate differential between the p-m rotor and the winding rotor, induced electromotive force will appear:

Connection of winding forms current loop, interaction between electromagnetic field caused by the current in the winding and the original permanent magnetic field transmits torque (the clutch is closed). When winding is disconnected, no current in the winding will transmit torque (the clutch is open). There is no mechanical action or no friction and abrasion.

By controlling the current in the winding, the transmission torque can be controlled to achieve speed control and soft start.

The slip power produced in the winding can be back to the supply terminal to achieve energy saving and guarantee temperature rise for normal work. For transmission of soft speed control or small power in a short time, it is not necessary for the user to save power, and the slip power can be consumed in the resistance inside of the cabinet.


● The function of clutch

There is no mechanical action, no friction or abrasion, and no need to start and stop the motor frequently.

● Starting torque reaches 220%

For normal asynchronous motor (including variable frequency motor), starting torque = (60%~80%)*rated torque. But the maximum overload torque of the motor = (180%~220%)*rated torque. Because of the clutch function of this soft starter, it can start the motor without any load first and then start the load with motor’s overload torque.

When it is beyond the maximum rated torque, the permanent magnetic coupling soft starter will slip but keep the maximum rated torque transmission.

3. Starting time can be adjusted on the scene

For the large moment of inertia load, extend the starting time to start the load on the scene and reduce motor selecting power.

4. Slipping protection under overload and overload quantity can be adjusted on the scene

When the system load changes, transmission of the maximum torque can be set flexibly. When it is beyond the maximum setting torque, the permanent magnetic coupling soft starter will keep slipping at the maximum torque, and the slipping process will not damage any components and it can last long.

5.The starting torque can be adjusted on the scene according to the load. Multiple starting curves can be preset in advance to be chosen on the scene according to the load.

6.The structure is simple and can be made into explosion-proof style which can be adaptable to harsh environments such as flammable, explosive, dusty, high or low temperature. There is no need of air conditioning and dust-free workshop.

Ⅳ、Product model and meaning

Example: YOTQ400/21

Permanent magnetic coupling soft starter

Height of frame center:400mm

Rated torque:2100 N•m

Ⅴ、Appearance, installation size and parameters

Remarks:1.D2, E2, F2 and G2 in the above table can be manufactured according to the actual size provided by the users.

2.The above table does not contain all the data; please contact us for more applications.

Table 1 form and dimension of YORQ short series permanent magnetic coupling governor (base number 355 ~ 630)

Table 2 : YORQ short series permanent magnet coupling speed regulator and matched motor power meter

Click to download information collection table