Guidelines for Grounding the FX2N
The best way to ground your application is to ensure that all the common and ground connections of your FX2N and related equipment are grounded to a single point。 This single point should be connected directly to the earth ground for your system。
For improved electrical noise protection, it is recommended that all DC common returns be connected to the same single-point earth ground。 Connect the 24 VDC sensor supply common to earth ground。
All ground wires should be as short as possible and should use a large wire size, such as 2 mm2 (14 AWG)。
When locating grounds, remember to consider safety grounding requirements and the proper operation of protective interrupting devices。
Guidelines for Wiring the FX2N
When designing the wiring for your FX2N, provide a single disconnect switch that simultaneously removes power from the FX2N CPU power supply, from all input circuits, and from all output circuits。 Provide over current protection, such as a fuse or circuit breaker, to limit fault currents on supply wiring。 You might want to provide additional protection by placing a fuse or other current limit in each output circuit。
Install appropriate surge suppression devices for any wiring that could be subject to lightning surges。
Avoid placing low-voltage signal wires and communications cables in the same wire tray with AC wires and high-energy, rapidly switched DC wires。 Always route wires in pairs, with the neutral or common wire paired with the hot or signal-carrying wire。
Use the shortest wire possible and ensure that the wire is sized properly to carry the required current。 The connector accepts wire sizes from 2 mm2 to 0。3 mm2 (14 AWG to 22 AWG)。 Use shielded wires for optimum protection against electrical noise。 Typically, grounding the shield at the FX2N gives the best results。
When wiring input circuits that are powered by an external power supply, include an over current protection device in that circuit。 External protection is not necessary for circuits that are powered by the 24 VDC sensor supply from the FX2N because the sensor supply is already current-limited。
Most FX2N modules have removable connectors for user wiring。 (Refer to Appendix A to determine if your module has removable connectors。) To prevent loose connections, ensure that the connector is seated securely and that the wire is installed securely into the connector。 To avoid damaging the connector, be careful that you do not over-tighten the screws。 The maximum torque for the connector screw is 0。56 N-m (5 inch-pounds)。
To help prevent unwanted current flows in your installation, the FX2N provides isolation boundaries at certain points。 When you plan the wiring for your system, you should consider these isolation boundaries。 Isolation boundaries rated less than 1500 VAC must not be depended on as safety boundaries。
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