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Download NJ-series CPU Unit Hardware User's Manual
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4 Installation and Wiring z Precautions when Grounding • If the same ground is used for both the signal lines and the enclosure, isolate the channel base (a grounded metal plate inside a control panel) with an insulating material Independent ground Insulating material Channel base Example: Insulating and Grounding an Enclosure • To prevent influence from leakage current from other electrical devices, electrically isolate the panel in which the Controller is housed from other devices. • If high-frequency equipment is present, then ground not only the high-frequency equipment but also the panel itself in which the Controller is housed. • As shown in the following diagram, when using shielded cable for I/O wiring, connect the shield near the Controller to the enclosure ground terminal. Follow the instructions in the Communications Unit manual for preparing shielded communications cable. Controller Output Common Common Shielded Cable Ground z Controller Ground Terminals The Controller has the following two ground terminals. Protective ground terminal: Always connected to the Controller chassis to prevent electrical shock. Functional ground terminal: Connected to a neutral point in the noise filter to provide a ground when power supply noise causes malfunctioning. When the functional ground terminal is correctly grounded, it is generally effective in suppressing power supply common noise. Occasionally, however, grounding this terminal will result in picking up more noise, so be careful when using it. AC side Controller side Controller Ground Terminals z Grounding for AC Power Supply Units When wiring to an AC Power Supply Unit, if one power supply phase of the equipment is grounded, always connect the grounded phase to the L2/N terminal. L1 L2/N NJ-series CPU Unit Hardware User’s Manual (W500) 4 4-5-6 Grounding Input 4-5 Control Panel Installation The NJ-series Controllers are designed to be mounted so that they are isolated (separated) from the mounting surface to protect them from the effects of noise in the installation environment (e.g., the control panel). 4-57
