H92904CC0500 Foxboro Engineering Power Module

Description

The PLC system is divided into logic circuit grounding and power circuit grounding, with three methods: common grounding, floating grounding, shell common grounding, and circuit floating grounding. It is generally best to use separate grounding methods for controllers and other equipment. When grounding, attention should be paid to: the grounding wire should be as thick as possible, and generally larger than 2mm2 should be grounded; The grounding point should be as close as possible to the controller, and the distance between the grounding point and the controller should not exceed 50m; The grounding wire should try to avoid the wires of the strong current circuit and the main circuit as much as possible. If it cannot be avoided, it should intersect vertically and the length of parallel wiring should be minimized as much as possible.

Practice has proven that grounding is often an important means of suppressing noise and preventing interference. A good grounding method can greatly suppress the coupling of internal noise, prevent the invasion of external interference, and improve the anti-interference ability of the system.

Suppress interference introduced by input/output circuits
In order to achieve complete isolation on input and output circuits, optoelectronic coupling has been widely used in control systems in recent years and has become one of the most effective measures to prevent interference.

Photocouplers have the following characteristics: firstly, they are sealed in a tube shell and will not be affected by external light interference; Secondly, due to the use of light to transmit signals, the connection between the ground wires of various component circuits is cut off; Thirdly, the dynamic resistance of the light-emitting diode is very small, while the internal resistance of the interference source is generally large, making the interference signal that can be transmitted to the input and output of the optocoupler very small; Fourthly, the transmission ratio of optocouplers is generally small compared to the amplification factor of transistors, far less sensitive to interference signals than transistors, and the light-emitting diodes of optocouplers can only emit light when passing a certain current.

Therefore, even in the case of high interference voltage amplitude, due to insufficient energy, the light-emitting diode cannot emit light, which can effectively suppress the interference signal. Due to the fact that the linear region of optocouplers can generally only be within a specific range, it should be ensured that the variation range of the transmitted signal is always within the linear region. To ensure linear coupling, it is necessary to strictly select optocouplers and take corresponding nonlinear correction measures, otherwise significant errors will occur.

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SAFT -163
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3ADT306000R1
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4783335CV1