We are no stranger to resistors but when it comes to braking resistor, many people are still quite vague. So what is a braking resistor? How many types is it? How is the application? All will be answer in the following article.
What is a braking resistor?
Braking resistor is a type of resistor installed for inverters in motor control applications that require short deceleration time, abrupt stop, large inertial load, changing moment, reversing load continuously, all kinds of lifting…
Braking resistors are usually classified by structure. There are 2 types of it that commonly used which are braking resistor with ceramic shell and with aluminum shell.
Ceramic shell braking resistor
This type is composed of an outer shell made of porcelain. With a capacity of 300W – 6000W.
- Large size.
- The durability is not as high as that of aluminum shell.
- Less heat dissipation than aluminum housing discharge resistance.
Aluminum shell discharge resistance
The shell is made of pure aluminum capable of withstanding the harsh environments of heat and dirt. Aluminum resistors are strong, safe and widely used in power circuits, inverters, AC Servo systems.
- Compact size.
- Withstands agitation.
- Good heat dissipation.
Working principle of discharge resistor
When the motor is subjected to fast braking, or has great inertia, the actual speed of the motor is higher than that of the inverter. At this time the inverter cannot brake the motor according to the pre-set time. The motor turns into a generator to discharge the energy back to the DC bus. Typically, the inverter will control the braking time of the motor reasonably so that no overload condition occurs. If the engine needs to stop quickly, this energy source will have to be consumed.
The braking resistor helps the inverter consume that power. When the DC bus voltage rises to a certain value, the inverter drives the transistor to apply DC bus voltage through the braking resistor. Resistors convert electricity into heat.
If there is no resistance, every time decelerates or brakes, the inverter may report an error due to over voltage on the DC bus.
How to choose braking resistors for the inverter
Imagine the braking resistor as a container when the voltage on the DC bus goes up it will discharge into the braking resistors and resistance parameters. If we choose the resistance parameter that is too small, the inverter discharges will slowly, in some cases, there will be errors or even affect the device and its life. If you choose the resistance parameter that is too large, discharge resistance too quickly causes the braking resistor to catch on fire.
Therefore, to choose the appropriate discharge resistance must rely on many factors such as: the capacity of the motor, the load of the motor, the inverter firm ….
In addition, when selecting discharge resistors, follow the instructions of the inverter manufacturer.
Where to buy discharge resistor?
Hao Phuong is the No. 1 unit in Vietnam specializing in distributing all industrial electrical equipment from leading brands such as Fuji Electric, Idec, Kansai, Circutor, … and also an integrator of industrial automation systems leading businesses in Vietnam. We have headquarters, branches in all major cities: Hanoi, Ho Chi Minh City, … and with 15 years of experience in supplying and handling inverter problems, we are ready to serve all requirements on discharge resistors for customers.
For further information, please contact the hotline: 18006547.