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Maintenance and Simple Troubleshooting of 3/6/10KV Soft Starters

Views: 31     Author: Site Editor     Publish Time: 2022-06-24      Origin: Site

There are many disadvantages in the direct starting of electric motors, especially high-voltage electric motors:

The starting current can reach 5 to 7 times of the rated current, which is easy to cause the motor winding to overheat and cause insulation aging and shorten the service life of the motor, resulting in excessive voltage drop in the power supply network. When the voltage is less than 0.85 times the rated voltage, it can cause low voltage protection, resulting in a large energy loss and waste of electric energy during startup, especially the frequent startup of the motor and the impact of the mechanical part of the motor on the gearbox, accelerating its aging. Therefore, it is very necessary to use soft start for high-power high-voltage motors in actual production.


CMV High-voltage Soft Starter Working Principle

3_6_10_KV Soft Starter XiCHiElectricThe complete CMV series soft starter is a standard motor starting and protection device used to control and protect high voltage AC motors. Standard CMV products are mainly composed of the following components: 

 high-voltage thyristor modules, 

✔ thyristor protection components, 

 optical fiber trigger components, 

 vacuum switch components, 

✔ signal acquisition and protection components, 

✔ system control,

✔ display components.


The control core of the CMV series is the microprocessor CPU. The microprocessor performs phase angle trigger control on the SCR to reduce the voltage applied to the motor, and then smoothly increases the motor torque by slowly controlling the voltage and current applied to the motor until the motor accelerates to full speed. This starting method can reduce the starting impulse current of the motor and reduce the impact on the power grid and the motor itself. At the same time, the mechanical impact on the mechanical load device connected to the motor is also reduced, so as to prolong the service life of the equipment and reduce the fault and downtime detection time.

When the motor runs at full speed, the motor current drops to the current value of normal full speed operation. The CMV series soft starter has a bypass output relay, so that the bypass high-voltage vacuum contactor is closed, so that the motor current passes through the bypass contactor to prevent The heat loss caused by the voltage drop generated by the SCR conduction improves the work efficiency and reliability.


The products are widely used in electric power, building materials, chemical industry, metallurgy steel, papermaking and other industries with rated voltage of 3000-10000V. It can be well matched with various electromechanical equipments such as pumps, fans, compressors, pulverizers, conveyor belts, elevators, etc. It is an ideal high-voltage motor starting and protection equipment.


CMV Soft Starter Routine Maintenance

The industrial site needs to be cleaned regularly to reduce dust particles in the surrounding environment. The CMV series high-pressure soft-lifting device should regularly clean the high and low pressure warehouses. During cleaning, brushes or blowing equipment can be used to clean the dust particles in the warehouse as a whole (the cycle is less than 20 days).

The cleaning of the thyristor valve block is also very important. When cleaning, blowing equipment with higher power can be used to blow the valve body from top to bottom, and clean the site after cleaning (the cycle is less than 6 months).

If the site environment is humid, the CMV series high-voltage soft starter should be dehumidified regularly to ensure the safe and normal operation of the equipment (the cycle is determined according to the site conditions).

Considering the factors such as vibration at the start of industrial field equipment, the secondary control wiring of the CMV series high-voltage soft starter should be checked regularly to see if the connecting wire is loose or falling off, and the loose or falling off contacts should be tightened (period of 3 months).


Common faults and Solutions of CMV soft starter

The CMV series is designed as a maintenance-free product. However, like other electronic equipment, this product should be regularly checked for dust pollution, moisture and industrial production environment pollution. Serious pollution will cause high voltage discharge and affect the heat dissipation of the SCR radiator. The soft starter has a variety of protection functions. When the protection function of the soft starter is activated, the soft starter will stop immediately, and the current fault information will be displayed on the LCD screen, the touch screen, and the device panel. Users can perform fault analysis according to the fault content.

Fault name Fault cause Solution
Mains power phase loss Phase loss during startup or in progress? Check whether the three-phase power supply is reliable
Phase sequence error Phase sequence reversed Adjust phase sequence or set to not detect phase sequence
Parameter missing Setting parameters lost? Check the settings of each function item and reset
Freq error Poor quality of power grid? Check if power grid quality is out of range?
Overcurrent in operation

Sudden heavier load?

Load fluctuates too much?

Adjust the load operation condition

Adjust overcurrent protection parameters

Phase current imbalance Phase loss or phase voltage imbalance Adjust the phase current unbalance protection parameters
Start Timeout

Heavy load start time is too short?

Current limit is too small?

Adjust ramp time

Adjust the current limit multiplier value

Electronic thermal overload Does the high current last too long for overload operation?

Check whether the motor current setting of the function item is correct?

Is it overloaded?

Overvoltage protection The main circuit power supply voltage is higher than the set value Adjust the overvoltage protection value

Check if mains voltage is too high

Undervoltage protection The main circuit power supply voltage is lower than the set value Adjust the undervoltage protection value

Check if mains voltage is too low

Ground protection The ground current is greater than the allowable value Check for ground current
Start over-frequency protection Over frequency of starting Reduce start frequency


XiCHi  CMV-S series soft start control device is mainly suitable for the control and protection of the start and stop of squirrel-cage asynchronous and synchronous motors.

The valve group is installed in the withdrawable KYN28 central high-pressure cabinet, and the thyristor valve body adopts the trolley installation method, which is convenient for users to check, test and maintain.


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