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What Is The Function Of The Terminal Block?

2022-10-22

In the power electronic wiring, when the equipment inside the screen and the equipment outside the screen are connected, they must pass through some special terminals. The combination of these terminals is called a Terminal Block. The function of the terminal block is to connect the lines of the equipment inside and outside the screen, and play the role of signal (current and voltage) transmission. With the terminal block, the wiring is beautiful and the maintenance is convenient. The connection between the long-distance lines is mainly reliable, and the construction and maintenance are convenient.

General equipment is controlled by PLC and upper computer. The input/output points of the PLC of the equipment are generally not directly connected to the actuator. Most of the input/output points are connected to the terminal block before/after entering/exiting the PLC. Looking at the circuit diagram, I found that these circuit boards are generally conversion circuits, which are finally connected to the actuator.

In fact, I found that it is also possible to directly connect to the actuator, why is it so troublesome to connect it to the circuit board? Is it to save input/output points? (For example: one output point controls one group of relays, and this relay controls multiple signals.)
The terminal block mainly has the following functions:
1. Isolation function. Generally, the PLC controls other equipment in the form of weak current control and strong current. Through the intermediate relay, the strong current equipment can be isolated from the PLC, but at the same time, it can also play a control role. In addition, if the external signal is short-circuited, if it is directly connected to the module, it may burn the module, and even if the circuit board or relay is burned, the cost is small.

2. Anti-interference, such as some loads are of the nature of interference sources, such as frequency converters, which have high-frequency harmonics, which are easy to interfere with the control of plc.

3. It is recommended to refer to the design requirements of the product in detail before making the design. The design method suggested in the manual is the design method that conforms to safety, isolation and anti-interference.

However, the function of the terminal block is mainly to isolate the signal, and the isolation includes the isolation of the module channel and the backplane bus and the isolation of the channel and the module power supply. Most modules have these two isolations. For details, please refer to the module specification. If the channel is not isolated from the backplane bus, the power supply of the CPU needs to share the ground with the module common terminal MANA. If the module L+ is not isolated from the channel, the module 24V power supply M needs to share the ground with the module common terminal MANA.

If the non-isolated module does not do the above points, the common mode voltage between different power supplies will affect the normal measurement, and even the reading overflow phenomenon will occur. If the sensor is not isolated, the power supply of the sensor also needs to be grounded with the common terminal of the module. The specific method is to short-circuit the negative terminal of the signal and the common terminal MANA of the module when measuring the current or voltage of the four-wire system.

We specialize in the production of terminal blocks, there are different types, Pcb Terminal Block and Din Rail Terminal Block. You can go to our website to browse. More Spring Terminal is on sale, which can be customized according to your needs. If you are interested, you can consult us. If you need some Terminal Pins or other Terminal Block Accessories, you can also consult us, we support customization and wholesale.

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