Fault detector for a tip and ring circuit, a method of protecting such a circuit and a power supply including the fault detector

A method of protecting a telecommunications network including a telephone wire-pair having a return conductor and an output conductor, comprising:

• detecting a ground fault on said wire-pair;
• characterizing said ground fault in terms of a value;
• determining, based on said value, if said ground fault is a fault of said return conductor or a fault of said output conductor;
• selecting a threshold based on said determining;
• and
• comparing said value to said selected threshold to determine if said ground fault violates a safety limit, wherein said determining, said selecting and said comparing are performed by a processor.

A power supply for a telecommunications network, comprising:

• a power converter configured to provide power to a telephone wire-pair having a return conductor and an output conductor, and
• a fault detector including:
• a passive sensor coupled between Earth and said wire-pair to detect a ground fault thereof;
• an amplifier having inputs coupled across said passive sensor and configured to characterize said ground fault in terms of a value;
• and
• a controller configured to receive said value via an output of said amplifier and compare said value to a threshold to determine if said ground fault exceeds a safety limit, said controller further configured to direct said power converter to reduce power provided to said wire-pair based on said compare.