A-B模块 6176M-17PT 输出模块

A-B模块 6176M-17PT 输出模块

6176M-17PT接地的目的通常有两个，一为了安全，二是为了抑制干扰。完善的接地系统是PLC控制系统抗电磁干扰的重要措施之一。

系统接地有浮地、直接接地和电容接地三种方式。对PLC控制系统而言，它属高速低电平控制装置，应采用直接接地方式。由于信号电缆分布电容和输入装置滤波等的影响，装置之间的信号交换频率一般都低于1MHz，所以PLC控制系统接地线采用一点接地和串联一点接地方式。

6176M-17PT集中布置的PLC系统适于并联一点接地方式，各装置的柜体中心接地点以单独的接地线引向接地极。如果装置间距较大，应采用串联一点接地方式，用一根大截面铜母线(或绝缘电缆)连接各装置的柜体中心接地点，然后将接地母线直接连接接地极。

接地线采用截面大于22mm2的铜导线，总母线使用截面大于60mm2的铜排。接地极的接地电阻小于2Ω，接地极好埋在距建筑物10～15m远处，而且PLC系统接地点必须与强电设备接地点相距10m以上。

6176M-17PT信号源接地时，屏蔽层应在信号侧接地；不接地时，应在PLC侧接地；信号线中间有接头时，屏蔽层应牢固连接并进行绝缘处理，一定要避免多点接地。多个测点信号的屏蔽双绞线与多芯对绞总屏蔽电缆连接时，各屏蔽层应相互连接好，并经绝缘处理，选择适当的接地处单点接地。

The purpose of 6176M-17PT grounding is usually two, one is for safety, and the other is to suppress interference. Perfect grounding system is one of the important measures for PLC control system to resist electromagnetic interference.

The system can be grounded by floating ground, direct ground and capacitive ground. For PLC control system, it is a high-speed low-level control device, should use direct grounding mode. Due to the influence of the signal cable distribution capacitance and the input device filter, the signal exchange frequency between the devices is generally lower than 1MHz, so the grounding wire of the PLC control system uses one-point grounding and one-point grounding in series.

The PLC system with 6176M-17PT centralized arrangement is suitable for parallel one-point grounding, and the central ground point of each device is led to the grounding pole by a separate grounding wire. If the distance between the devices is large, the one-point grounding method should be used in series. Connect the cabinet center ground point of each device with a large-section copper bus (or insulated cable), and then connect the ground bus directly to the ground pole.

Use copper wires with a cross section greater than 22mm2 for the ground cable and copper bars with a cross section greater than 60mm2 for the main bus bar. The grounding resistance of the grounding pole is less than 2Ω, the grounding pole is best buried 10 to 15m away from the building, and the PLC system ground point must be more than 10m away from the ground point of the strong current equipment.

When the 61766-17PT signal source is grounded, the shielding layer should be grounded on the signal side; When not grounded, should be grounded on the PLC side; When there is a joint in the middle of the signal line, the shielding layer should be firmly connected and insulated, and multi-point grounding must be avoided. When the shielded twisted pair of multiple measuring points signals is connected to the multi-core twisted total shielded cable, the shielding layers should be connected to each other, and be insulated, and the appropriate grounding point should be selected.