Working principle of magnetic switch, magnetic switch wiring diagram

Working principle of magnetic switch

1. The reed switch in the magnetic switch is also called a magnetron. It is a switching element controlled by magnetic field signals. When there is no magnetism, the circuit is disconnected and can be used to detect mechanical movement or the status of the circuit. When the magnetic switch is not in working condition, the two reeds in the glass tube are not in contact. If a magnetic substance approaches the glass tube, under the action of the magnetic field, the two reeds will be magnetized and attracted to each other, thus completing the circuit. When the magnetic material disappears, without the influence of external magnetic force, the two reeds will separate due to their own elasticity, breaking the circuit.

2. There is a kind of magnetic switch, which is a reed switch with multiple points or one point set inside a closed plastic tube or metal. The entire container is hollow, and a floating ball with a ring magnet is installed inside. The reed switch and the floating ball are controlled by a fixed ring. Position, the float can float within a certain range. The on and off action of the switch is generated by the magnet in the float attracting the contacts of the reed switch.

3. There is another kind of magnetic switch, which is often called a proximity switch, also called a door magnetic switch or an induction switch. It has a standard size plastic shell. The reed switch is potted inside the black shell. The wire is led out and the other half of the plastic shell with magnet is fixed at the other end. When a magnetic substance approaches the switch with the wire at a distance of about 10mm, the switch will Send a switch signal.



Principle of magnetic switch cylinder

It installs a permanent magnetic ring on the cylinder piston and a reed switch on the cylinder shell. The switch is equipped with a reed, a protection circuit, an action indicator light, etc., which are all sealed in a box with resin. When the piston equipped with a permanent magnet moves near the reed, the magnetic field lines pass through the reed to magnetize it, and the two reeds are attracted to contact, and the switch is turned on. When the permanent magnet returns and leaves, the magnetic field weakens, the two reeds spring open, and the switch is turned off. As the switch is turned on or off, the solenoid valve is reversed, thereby realizing the reciprocating motion of the cylinder.



How to wire a magnetic switch and the magnetic switch wiring diagram

1. There are two-wire and three-wire magnetic switches. Three-wire magnetic switches are divided into NPN type and PNP type. Their wiring is different.

2. The wiring of the two-wire magnetic switch is relatively simple. The magnetic switch is connected in series with the load and then connected to the power supply.

3. The wiring of the three-wire magnetic switch: the red (brown) wire is connected to the positive terminal of the power supply;the blue wire is connected to the 0V terminal of the power supply;the yellow (black) wire is the signal and should be connected to the load. The other end of the load is connected like this: for NPN type magnetic switch, it should be connected to the positive terminal of the power supply;for PNP type magnetic switch, it should be connected to the 0V terminal of the power supply.

4. The load of the magnetic switch can be a signal lamp, a relay coil or a digital input module of a programmable controller PLC.

5. Special attention needs to be paid to the type selection of the three-wire magnetic switch connected to the PLC digital input module. PLC digital input modules can generally be divided into two categories: the public input terminal of one type is the power supply 0V, and the current flows out from the input module (Japanese model). At this time, an NPN type magnetic switch must be selected;the public input terminal of the other type It is the positive terminal of the power supply, and the current flows into the input module, that is, well input (European mode). At this time, a PNP type magnetic switch must be selected. Don't make the wrong choice.

6. The two-wire magnetic switch is limited by the working conditions. When it is turned on, the switch itself produces a certain voltage drop, and when it is turned off, a certain residual current flows. This should be considered when selecting. Although the three-wire magnetic switch has one more wire, it is not troubled by unfavorable factors such as residual current and works more reliably.

7. Some manufacturers lead out the "normally open" and "normally closed" signals of the magnetic switch at the same time, or add other functions. In this case, please follow the product manual for specific wiring.