Current loop surge protectors (surge protective devices) are used in industrial, manufacturing, and commercial facilities to measure speed, volume, weight, flow or other variables.  The current loop utilizes a continuous voltage with a varying current level that changes in direct proportion to the measured variable.  The vast majority of current loop units are 24 Vdc, 4-20 mA.  Other, non-standard voltages are available.

The current travels from the meter or scale to the sensor (motion, load, volume, etc.) and back.  As the variable increases the current changes in direct correlation.  This current is then measured and the resulting change in current indicates the variable to be measured. SSI manufactures surge protectors for both standard current loop and HART digital data systems.

Each current loop is 2 wire, with or without shield, plus a ground wire.  We offer both conduit type and NEMA 1 (indoor use) enclosures depending on the desired location of the current loop surge protector.  

Typical applications for current loop surge protective devices include wastewater treatment facilities, truck scales, and concrete plants.

Current Loop SPD Data Sheets