C62.39-2012 - IEEE Standard for Test Methods and Preferred Values for Self-Restoring Current-Limiter Components Used in Telecommunication Surge Protection
This standard sets terms, test methods and measurement procedures for series connected, self-restoring current limiter components used in low-voltage telecommunication circuit surge protectors. It is only applicable for components in telecommunications circuits with voltages equal to or less than 1000 V rms or 1200 V dc. The self-restoring current limiters covered by this standard have the following properties: · Excessive current causes a transition from a low-resistance state to a high-resistance state · Reverts to a low-resistance state when the excessive current ends · Directly operated by the current flow through the component · Solid-state (no moving parts) · Withstands specified levels of impulse · Withstands specified AC voltage levels when in the high-resistance state Examples of this type of current limiter technology are positive temperature coefficient step-function thermistors of ceramic or polymeric material and silicon semiconductor based electronic circuits. This standard does not cover self-restoring current limiter components used in other applications, such as heaters, inrush-current limiters or sensing devices. Current interrupting type components, which reduce the current to zero by a mechanical circuit break, are not covered by this standard. In this standard, a telecommunications circuit is a circuit that uses metallic conductors to handle the remote transmission of information, such as data, communications and signalling.