CCr

What does 071 mean?

A system failure has occurred due to strong interference injection on the control cables. This can be caused by inadequate shielding or ground/earth loops in the wiring, leading to unstable operation.

• Inadequate cable shielding: Control cables (e.g., encoder cables, analog signal cables) are not properly shielded, or their shields are not terminated correctly at both ends (or single-ended where required).
• Ground loops: Multiple grounding points for the same circuit create differential potentials, leading to circulating currents and noise injection into signal lines.
• Proximity to noise sources: Control cables routed too close to high-current power cables, VFD output cables, contactors, or other sources of electromagnetic interference (EMI).
• Faulty grounding connections: Loose or corroded ground connections on the control panel, device chassis, or motor frame, impairing effective noise dissipation.
• Unfiltered power supply: The power supply for the control system (e.g., 24VDC for inputs/outputs) has insufficient filtering, allowing mains-borne noise to propagate.

Click steps to track your progress.

1. 1

   Verify all control cable shields (e.g., for terminals X2/AI1, X4/ENC_A) are correctly terminated at the device's chassis ground and, if applicable, at the sensor/encoder end (single-point grounding is often preferred for analog).

2. 2

   Inspect cable routing to ensure control cables are separated from power cables (e.g., motor cables, AC input) by a minimum distance (e.g., 200mm) or by using metal conduit/trays.

3. 3

   Measure potential differences between various ground points in the control panel and machine frame (e.g., device chassis, motor frame, PLC ground) to identify ground loops.

4. 4

   Check the integrity of all grounding connections, including the main protective earth (PE) connection to the control panel and device (e.g., resistance from PE terminal to chassis).

5. 5

   Install ferrite cores on control signal cables (e.g., analog input/output, encoder feedback) near the device to attenuate high-frequency interference.