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Contactor is an automatic electromagnetic switch for long-distance frequently connected or disconnected AC and DC main circuit and high-capacity control circuit. The main control object of a contactor is the motor, it can be used to control other loads as well.
According to the current types that through the main contacts, contactor is divided into AC contactor and DC contactor. The structure and working principle of both are basically the same, which mainly consists of three parts, electromagnetic mechanism, contact system and arc-extinguishing equipment. In the electrical control circuit of machine tool, AC contactor is mainly used. This article focuses on the basic structure of the AC contactor.

DC contactor is mainly used for remotely connecting and disconnecting the DC circuit, as well as frequently starting, stopping, reversing and plug braking the DC motors. It's also widely used for connecting and disconnecting the lifting electromagnet, solenoid valve, clutch's magnetic coils. DC contactor has two structure of stereoscopic arrangement and plane arrangement, some products are derived on the basis of AC contactor. Therefore, structure and working principle of the DC contactor are basically the same as that of AC contactor, which mainly consists of three parts, electromagnetic mechanism, contact system and arc-extinguishing equipment.

What is a power line filter? What does a power line filter do? A power line filter, also called EMI power line filter, is a passive bi-directional network, electrical equipment which effectively filters the particular frequency point in the power line or the frequency out of the particular frequency point. Power line filter is to get a certain frequency power supply signal or the power supply signal after eliminating a certain frequency through connecting power supply filter in power line...

What is a solid state relay(SSR)? A solid state relay is a non-contact switch fully composed of solid state electrical-element, which can drive high-current load with a small control signal. It can achieve switching on and off with no contact and no spark due to the switching characteristics of electrical element (i.e. semiconductor components like switch transistor, triac and so on). Solid state relay has such following advantages over electromagnetic relays: high reliability, no contact, no spark, long life, fast switching speed, strong anti-interference ability, and small size.

What is a servo motor? Servo motor is the motor which controls mechanical components operation in servo system. Servo motor can convert voltage signal to torque and speed, then to drive the control object. The control speed and position accuracy is very high. In auto control system, servo motor can response rapidly as executing component, convert the receiving electrical signal to angular displacement or angular velocity output of motor axis. The main feature is, when signal voltage is zero and no self-rotation, rotation speed will descend at even speed along with the torque increasing. Servo motor has 2 types, DC servo motor and AC servo motor.

Stepper motors is used in open-loop control, thus it is simple, low cost and can be widely used. However, the open-loop control of the stepper motor cannot avoid the inherent disadvantages of the stepper motor itself, that is, resonance, oscillation, step loss and difficult to achieve high speed. Correspondingly, the closed-loop control of stepper motor can make up these shortcomings, and have the advantages of open-loop drive and brushless DC servo motor.

The servo drive is a kind of controller to control the servo system. Its function is similar to the frequency effect on ordinary AC motor, which belongs to a part of the servo system and is mainly applied in high-accuracy positioning system. Generally, the servo motor is controlled by three ways, location, speed and torque, so as to realize high precision positioning of transmission system.

Stepper motor is an actuator transforming electric pulse into angular displacement. Popularly, when receiving a pulse signal, the stepper motor will rotate a fixed angle (namely"stepping angle") according to the direction set for the stepper motor. The angular displacement volume can be controlled by controlling the pulse number to achieve the purpose of positioning accurately. In the meantime, the rotational velocity and acceleration of motor can be controlled by controlling the pulse frequency to achieve the purpose of speed control.

Nowadays, with the continuous development of technology, AC servo motor technology gradually replaced the DC motor as the leading executive motor with its excellent cost performance. The mature technology of AC servo system also makes the market develop rapidly and become one of the supporting technologies of industrial automation. So what are the main functions of servo system and how is it classified? Continue and you will learn about that.

Motion controller usually adapts two types of command mode to control servo motor:
Digital pulse
This mode is similar to the control mode of stepper motor. The motion controller sends"pulse/direction" type pulse command signal to servo driver, when servo driver operates in position control mode, position closed loop is completed by servo driver. This mode of servo motor has the advantages that system debugging is simple and is difficult to cause interference, but has the disadvantage that the response of servo system is slightly slow.
Analog signal
In this mode, motion control system sends/-10V analog voltage command to servo driver and receives position feedback signals from position detection elements, such as motor encoder or linear grating, etc., when servo driver operates in speed control mode, position closed loop is completed by motion controller. Europe and America servo products mostly adapt such operation mode, which has the advantage that response of servo is rapid, but the disadvantage is that they are sensitive to site interference and debugging is complex.

There are some notes for the users when installing and using the servo motor. Take care of servo motor and it can work better and longer. The article briefly illustrates some precations for installation and usage of servo motor from serveral aspects: oil and mater resistant protection, tension reduction for servo motor cable, allowable shaft terminal load and so on.

Users often feel confused about the three braking ways of servo motor: electromagnetic braking, regenerative braking, and dynamic braking. As a result, they selected the wrong accessories. The article will tell you the differences among them and give some tips about the accessories selection.