Magnetic switches are a special type of switch. We often see automatic doors in some shopping malls or office buildings. When someone approaches a door, the door will open automatically. This is actually a kind of magnetic switch. Today, we mainly understand how to connect the magnetic switch.
Magnetic switch function
The magnetic proximity switch is a kind of proximity switch. The proximity switch is one of the many types in the sensor family. It is a position sensor that uses an electromagnetic working principle and is manufactured with advanced technology. It can change the positional relationship between the sensor and the object, convert the non-electricity or electromagnetic quantity into the desired electrical signal, so as to achieve the purpose of control or measurement.
How to connect the magnetic switch
1. The proximity switch has the difference between the two-wire system and the three-wire system. The three-wire proximity switch is divided into NPN type and PNP type. Their wiring is different.
2. The wiring of the two-wire proximity switch is relatively simple, and the proximity switch and the load can be connected to the power supply in series.
3. Connection of three-wire proximity switch: Red (brown) wire is connected to the positive terminal of the power supply; blue wire is connected to the power supply 0V terminal; yellow (black) wire is the signal and should be connected to the load. The other end of the load is connected in the following way: For the NPN type proximity switch, it should be connected to the positive terminal of the power supply; for the PNP type proximity switch, it should be connected to the 0V terminal of the power supply.
4. The load of the proximity switch can be a signal lamp, a relay coil, or a digital input module of a programmable controller PLC.
5. Special attention must be paid to the type selection of the three-wire proximity switch connected to the PLC digital input module. PLC digital input module can generally be divided into two categories: a common input is the power supply 0V, the current flows from the input module (Japanese mode), this time, we must use NPN type proximity switches; another type of common input For the positive terminal of the power supply, the current flows into the input module, ie the well-type input (European mode). At this time, the PNP type proximity switch must be used. Do not choose the wrong one.
6. The two-wire proximity switch is limited by the working conditions. When the switch is turned on, the switch itself generates a certain voltage drop. When the switch is turned off, there is a certain amount of residual current flowing. The selection should be considered. Although the three-wire proximity switch has one more line, it is not affected by the unfavorable factors such as residual current and the operation is more reliable.
7, some manufacturers will be close to the switch "normally open" and "normally closed" signal at the same time lead out, or add other features, such a situation, please follow the product specification specific wiring.