10kV Motor Soft Start device for vertical roller mill

Roller Mill Soft Start Project Overview:

Customer: a ceramic factory
Industry: Chemical

Load Type: Vertical Roller Mill

Vertical roller mill is a grinding equipment that integrates fine crushing, drying, grinding, powder selection and transportation. It is widely used in grinding and ultra-fine grinding of various solid materials in cement, building materials, electric power, metallurgy, chemical industry, non-metallic minerals and other industries.

Soft Starter model: CMV-710-10 (voltage class: 10kV, power: 710kW)

CMV series soft starter is used for starting, control, protection and soft stop of three-phase voltage 3kV, 6kV, 10kV  squirrel-cage AC asynchronous and synchronous motors.

Soft starter parameter setting:

Starting voltage: 40%

Current limit multiple: 350%Ie

Startup time: 10s

CMV high voltage soft starter Performance characteristics

• Multiple trigger modes

The combination of single-phase optical fiber and multi-point electromagnetic triggering technology realizes the isolation between the trigger detection of high-voltage thyristor and the low-voltage control loop, which is safe and reliable.

• Multiple communication interfaces
  

Equipped with RS-485 communication interface and standard Modbus communication protocol, it can communicate with the host computer or centralized control center.

• Friendly man-machine interface

LCD or touch screen display system, user-friendly operation interface.

• Multiple control methods

Adjust according to the load characteristics to meet the requirements of on-site working conditions.

• Redundant design

High reliability, the device is equipped with a vacuum contactor that can directly start the motor. If a fault occurs, the vacuum contactor is used to directly start the motor to ensure the continuity of production.

• Anti-interference

All circuit boards have undergone strict EMC electromagnetic compatibility, high and low temperature aging experiments, so as to have high anti-interference ability.

• Patented design of radiator

It greatly improves the heat dissipation efficiency of the radiator, ensures the safe use of the thyristor, and prolongs the service life of the equipment.

• Standardized design and manufacture

Reliable quality, design, production and delivery process are strictly in compliance with IS09001 standards.

• Remote communication monitoring function

Modbus communication function to realize remote monitoring and start-stop control. The running status and running parameters of the motor can be viewed through the relevant background system.

Brief description of 3-phase AC motor starting method

Because of its simple structure, reliable operation, convenient maintenance and low price, three-phase AC motors are widely used in the mechanical power of electric drive production, and are widely used in machinery, chemical industry, textile and petrochemical industries.

When the motor is directly started under constant voltage, the starting current is about 4-7 times of the rated current. Because the speed has to rise from 0 to the rated speed in a very short period of time, it will cause shock during the start-up process, which will easily lead to wear or even damage to the transmission mechanism. At the same time, under the impact of the large current at the moment of starting, the voltage of the grid is caused to drop, which affects the normal operation of other equipment in the grid. Due to the voltage reduction, the motor itself is difficult to start, resulting in the motor stall, and may burn out the motor in severe cases.

Therefore, how to reduce the large current impact of the instantaneous start of the asynchronous motor is the primary problem in the operation of the motor. To this end, we must try to improve the starting method of the motor, so that the motor can start smoothly, so there are various current-limiting starting methods.

Features of soft start

1. Smooth start, no inrush current. In the process of starting the motor, the soft starter gradually changes the conduction angle of the thyristor, so that the starting current of the motor rises smoothly from zero to the maximum value. The whole process runs smoothly, the reliability of the motor power supply is high, the impact torque on the mechanical load is reduced, the impact on the motor itself is small, and the service life of the motor and the entire equipment is prolonged.

2. It can realize smooth deceleration until stop, that is, it has the function of soft stop. It can overcome the disadvantages of sudden power failure on the mechanical part of the equipment, and prolong the service life of the equipment.

3. Various parameters of the soft starter are adjustable. It can be selected according to the load characteristics and grid characteristics to adjust to the best state.

Traditional motor starting method

1. The stator string resistance starts

   When the motor starts, a resistor is connected in series in the three-phase stator circuit, so that the voltage applied to the motor winding is lower than the grid voltage. After starting, the resistor is short-circuited and the motor runs at the rated voltage. This method applies to low-voltage motors. The disadvantage of this method is that the starting torque decreases with the square relationship of the stator voltage, and because it is a step-by-step starting, the starting characteristics are not smooth, so it is only suitable for no-load or light-load starting occasions. The energy is large, and it is not suitable for motors that are frequently started. This device requires a reload boot, so this method is not available.

2.  Y/△ start

   In normal operation, the load has no strict requirements on the starting torque of the motor, and the starting current of the motor must be limited, and the squirrel-cage asynchronous motor whose stator winding is connected into a triangle can be started by Y/△. When starting, connect the stator into a star shape, and then change it to a triangle when the motor is close to the rated speed. The motor is connected in a star shape, and the starting current is only 1/3 of the original delta connection. Y/△ is a step-down start, which is realized at the expense of power in exchange for low voltage. The main disadvantage is that when the startup is switched from star to delta connection, there will be large secondary current and torque fluctuations, which will easily cause mechanical and electrical stress and lead to failure. This method does not apply to this device.

3. Autotransformer startup

   Autotransformer starting is suitable both for delta-connected motors in normal operation and for star-connected electric starting. When starting, first reduce the motor stator voltage through the three-phase autotransformer, and then cut off the autotransformer after starting to restore the motor stator voltage to the rated value. The transformation ratio of the autotransformer is adjustable within a certain range, but its limited output voltage transformation ratio series limits the choice of ideal starting current, and the cost of the autotransformer is high.

Comparison of soft start and traditional start of motor

How to order

Please provide the following information when ordering:

• Topside Power Condition

• Motor model, rated power, rated voltage, rated current, rated speed

• Motor drag load type (fan, water pump, etc.)

• In and out wiring of equipment

• Installation position condition, cabinet color

• Equipment usage environment

Customers in plateau, high altitude (>2000m), high cold (<-15℃), high temperature (>+50℃), serious pollution by salt spray, and high humidity areas, please explain in advance

Note: If you have other special requirements (such as increasing the protection level), please contact us.