The Leakage Current Monitor (LCM) system measures the resistive component of continuous leakage current in gapless metal oxide surge arresters (MOSAs). The LCM is connected to the arrester and consists of three main parts:

* A current probe attached to the connector of either a clip-on current transformer or a toroid transformer (in permanent installations).
* A field probe connected to the current probe via a coaxial cable and an adapter positioned near the base of the arrester, to pick up the capacitive current component.
* A leakage current instrument that uses harmonic analysis of current and field probe signals to determine the resistive component of the leakage current.

The LCM will also measure metal-enclosed surge arresters for gas insulated substations (GIS). In this case, a capacitive GIS coupler is connected to the field probe.

* Portability. Lightweight, battery-operated instrument is easily transportable for inspecting surge arresters on a regular basis.
* Arrester ID. Provides unique identification of each surge arrester, making data management easy. The LCM can store 1000 surge arrester IDs and measurements performed in the field.
* Data Management. Define individual surge arrester types, including operational parameters. Software functions include evaluating groups of surge arresters by arrester type or by region.
* Cost-Effective. Inspecting a surge arrester takes less than 10 minutes on location and can be performed with the arrester in live operation, without disturbing power distribution.
* Continuous Monitoring. Permits investigating details in leakage current changes versus time. Can also be used for continuous registration in substations, which is important for system operation reliability. Available solutions include online configurations using modem communication between the LCM and PC software.