scope:

INTRODUCTION

The Sleeper Insulation Tester (SIT) is designed to detect leakage of TI21 track circuit signals into the sleepers. It provides the operator with an aud ible and visual indication of leakage level. The SIT allows a specific TI21 frequency to be checked witho ut interference from any other TI21 track circuits or any other frequency.

The SIT also has an AC detection mode that can be used to detect any AC signal up to approx. 3 kHz ; this mode is useful to detect high levels of harmonic leakage in DC 3rd rail, electrified areas. Note that the visual indication is not available to the operator in this mode.