First, several factors must be determined in the selection of the proximity switch?
- Is it inductive or capacitive? (Inductive metal, capacitive metal, wood, paper, oil, plastic, etc.)
- Do you need a round or square shape? (How big is the diameter of the circle?)
- How big is the sensing distance?
- Is it front-end or upper-end?
- Is there a requirement for the line length? We are generally 2 meters? Large quantity can be customized)
- Is it DC or AC? (AC 2 line, DC 3 line)
- Is it normally open or normally closed?
- What is the length of the wire near the switch? The standard wire length is 1.5 meters, and can also be customized according to customer requirements.
Second, inductive proximity switch
- Principle: The inductor consists of an inductor, a capacitor and a transistor, and generates an alternating magnetic field. When a metal object approaches the magnetic field, an eddy current is generated in the metal object, causing the oscillation to stop. After the amplification process, it is converted into a transistor switch signal output.
- Features: A, good anti-interference performance, high switching frequency, greater than 200HZ. B, can only sense metal
- Application on various mechanical equipment for position detection, counting signal picking, etc.
Third, capacitive proximity switch
- Principle: When an object approaches the induction pole piece, the pole piece and the object form a capacitor, which causes the state of the oscillation pole to change, and the rear pole amplifies the change and outputs a transistor switching signal.
(1) It can detect not only metals but also plastics, glass, water, oil and other substances.
(2) It is susceptible to interference and pay attention to the installation location.
(3) The sensing distance can be adjusted.
(4) The frequency is about 50HZ.
(5) Application: According to its characteristics, it is especially suitable for the detection of non-metallic materials, such as food, chemical and other industries.
Fourth, the main technical parameters of the proximity switch
- Detection distance: The distance between the detected object and the detection surface of the proximity switch when the detected object moves to the proximity switch detection surface in the specified direction.
- Hysteresis (differential distance): The difference between the detection distance and the return distance.
- Response frequency: The output frequency that the switch can react in every second.
- Working voltage: the voltage allowed for normal operation
- Load capacity: maximum allowable output current
- Output form: NPN normally open, NPN normally closed, PNP normally open, PNP normally closed