D138-002-001 MOOG 穆格控制器 加密狗系列 D138-002-002

D138-002-001 MOOG 穆格控制器 加密狗系列 D138-002-002

为了安全和抑制干扰，系统一般要正确接地。系统接地方式一般有浮地方式、直接接地方式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。

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20mm2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，接地极最好埋在距建筑物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。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点。

For safety and suppression of interference, the system is generally properly grounded. The system grounding methods generally include 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 centrally arranged plc system 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 series one-point grounding method should be used. Use a large section copper bus bar (or insulated cable) to connect the cabinet center ground point of each device, and then connect the ground bus directly to the ground pole. Use a copper conductor with a cross section greater than 20mm2 for the ground cable, and a copper bar with a cross section greater than 60mm2 for the main bus bar.