NEWS
NEWS
LATEST NEWS
- Where can use it?
- Our Team
- Munich Electronic Exhibition
- Hannover Messe 2019
- Hannover Messe 2018
CONTACT US
Tel: 86-577-62840011
Fax:86-577-62840011
Mobile Phone:+8613355775769
WhatsApp:8613355775769
E-mail:win@winelectrical.com
Necessity and difference of built-in and external bypass contactor of soft starter
The contactor connected in parallel with the soft starter is called a bypass contactor, because the long-term use of the soft starter to start will cause a lot of pressure on the thyristor. Excessive current of the thyristor for a long time is not good for it. At the same time, it is also easy to cause problems by relying on the circuit board to trigger the thyristor. It is better to use a traditional contactor to maintain it, because the soft start is only useful during the motor starting process and runs at the power frequency. It is the same as the usage of ordinary motors, so it is still reliable to use traditional contactors. Due to the shortcomings and technical difficulties of the online operation of the motor soft starter, the manufacturer has directly developed a bypass softstarter, that is, the motor is bypassed to run on the contactor after the motor is started. Its advantage is that it avoids the shortcomings of on-line operation of thyristors, especially without mechanical air cooling. However, it also brings disadvantages: the circuit is complicated and the system reliability is reduced; the powerful intelligent controller cannot be fully utilized, and some cannot protect the motor; Soft start is a device that can reduce the starting current of the AC motor when starting. When the motor completes the starting process, the device can start the bypass contactor according to the set time to remove the soft start from the main circuit of the motor, and the bypass contactor is used. The main contactor of the motor and the motor is connected to the motor power circuit. There are also two types of soft starters. One does not use an extenal contactor and runs directly after starting. It is a built-in bypass contactor. The other is that an external bypass contactor is required, which is cheaper and automatically switches to contactor operation after startup. This soft start can start multiple motors at the same time, so that one machine can be used for multiple purposes. www.shuyitop.com;Tel/Fax: 0086-577-62840011 WhatsApp: 008613355775769
Why is the starting current still large after the motor uses a soft starter?
When a high-power motor starts, the starting current is large, which will cause serious fluctuations in the grid voltage. In order to solve this problem, when the speed regulation is generally not required, a soft starter can be used to reduce the voltage. However, the reduction of the starting current during the step-down starting will also greatly reduce the starting torque, so it is not suitable for starting with a rated load, but generally suitable for no-load or light-load starting. When the motor needs to be started with load or has high requirements for speed regulation, the frequency converter is generally used to start, which can reduce the starting current under the premise of ensuring a larger starting torque. In addition, both step-down and constant voltage-frequency ratio (constant air-gap magnetic flux) can adjust the speed, but the step-down speed adjustment will soften the mechanical characteristics of the motor, and the speed adjustment range is small. The constant voltage frequency ratio has a large speed regulation range, and the mechanical characteristics of the motor are hard. The constant voltage frequency ratio speed regulation has so many excellent special effects, why not apply it on a large scale, the answer is that the cost of the soft starter is very low, the AC power voltage regulation circuit can be realized, and the high-power inverter is expensive. The possible reasons why the starting current of the motor is still relatively large after the soft starter is used are as follows: 1. Because of the motor system controlled by soft start, the capacity of the motor is relatively large, mostly ranging from more than 75KW to several hundred kilowatts; 2. Most of the motor systems controlled by soft start are hard loads. If the current limit start method is adopted, it should be set to at least twice the rated value of the motor or three times the rated current value, so as to basically meet the technological requirements of the system. Reasons why the motor soft starter cannot start: The parameter setting is unreasonable Solution: Re-adjust the parameters, increase the initial voltage appropriately, and lengthen the time appropriately. Full load start at start Solution: try to reduce the load when starting. Motor phase loss Solution: Check the motor and peripheral circuits. The main component thyristor in the soft starter is short-circuited Solution: Check whether the motor and grid voltage are abnormal, and contact the manufacturer to replace the thyristor. Filter board breakdown short circuit Solution: replace the filter board. www.shuyitop.com; Tel/Fax: 0086-577-62840011 WhatsApp: 008613355775769 #softstarter #motorsoftstar #softstarters #softstartechnology #softstartermarket #softstarterprice #builtinbypasssoftstarter #ZJSHUYI #Chinashuyi #acmotorsoftstarter #3phasestarter #3phasesmotorsoftstarter #durablesoftstarter #bypassmotorsoftstarter #onlinesoftstarter #acsoftstarter Leave a Reply Your email address will not be published. Required fields are marked * However, the reduction of the starting current during the step-down starting will also greatly reduce the starting torque, so it is not suitable for starting with a rated load, but generally suitable for no-load or light-load starting. When the motor needs to be started with load or has high requirements for speed regulation, the frequency converter is generally used to start, which can reduce the starting current under the premise of ensuring a larger starting torque. In addition, both step-down and constant voltage-frequency ratio (constant air-gap magnetic flux) can adjust the speed, but the step-down speed adjustment will soften the mechanical characteristics of the motor, and the speed adjustment range is small. The constant voltage frequency ratio has a large speed regulation range, and the mechanical characteristics of the motor are hard. The constant voltage frequency ratio speed regulation has so many excellent special effects, why not apply it on a large scale, the answer is that the cost of the soft starter is very low, the AC power voltage regulation circuit can be realized, and the high-power inverter is expensive. The possible reasons why the starting current of the motor is still relatively large after the soft starter is used are as follows: 1. Because of the motor system controlled by soft start, the capacity of the motor is relatively large, mostly ranging from more than 75KW to several hundred kilowatts; 2. Most of the motor systems controlled by soft start are hard loads. If the current limit start method is adopted, it should be set to at least twice the rated value of the motor or three times the rated current value, so as to basically meet the technological requirements of the system.
- Vivian
- 11 5 月, 2023
- 6:57 下午
Your needs are my pursuit, your trust is my responsibility
We have an experienced team to provide services for you.
