Report on Analog Leased Line Withdrawal of Service and Transition Options for Power System Applications (TR 116)

Protective relay communications (teleprotection) applied using audio tones over leased voice grade channels is still in use today. It has become common for phone companies to no longer offer voice grade leased lines. For the telcos thatstill offer the service, guaranteed performance of those lines, that are called for in IEEE Std C37.93TM-2004 (Reaff. 2010), are no longer supported. Transitioning to a new, dedicated, digital teleprotection system is ideal but may not be an option for users that need to lease circuits from a third-party provider. Alternatives to leased voice grade channels are still available and may be a good solution for power utilities.