Harmonious co-existence of Power and Telecommunication networks: A study on Low Frequency Induction (LFI) risks and Mitigation measures

While such co-location is the need of the hour and offers planning efficiency, it introduces the challenge of Low Frequency Induction (LFI), a phenomenon where unbalanced alternating currents in power lines induce voltages in a nearby telecom cables, especially during fault conditions. This LFI, if left unmitigated, can seriously affect the service continuity, equipment integrity, and operational safety of personnel across multiple sectors.

An important but often overlooked aspect is the phenomenon of the Earth Potential Rise (EPR) that occurs during ground fault events at substations and other High Voltage (HV) installations.

This can induce hazardous touch and step voltages, and transfer voltages onto nearby metallic structures, including telecommunication cables, joints, pipelines, and terminals. The presence of telecom assets within the EPR influence zone of substation and other High Voltage installations can result in equipment damage, signal distortion, and safety hazards for field personnel. Therefore, it is essential to identify and verify the extent of the EPR zone around substations and ensure the non-presence or adequate protection of telecommunication cables, joints, pipelines, and terminals within this region.

This paper aims to explore the mechanisms, risk scenarios, and mitigation strategies associated with LFI, with a focus on achieving harmonious coexistence between power and telecom systems. It will cover the following aspects:

• Physics of inductive coupling, including mutual impedance and Carson’s equations. • Existing International standards and prevailing guidelines for coordination of Power and

Telecommunication networks. • Parameters influencing the LFI such as parallel length, separation distance, soil resistivity and fault current magnitude and their impact. • Practical engineering mitigation measures, including shielding, optimized route planning, and conversion to fibre optics. • Engineering considerations and coordination protocols necessary to assess EPR zones and maintain safe separation between power and telecom systems. The paper will also highlight the role of institutional coordination mechanisms in ensuring proactive planning and conflict resolution between stakeholders.