Current repeaters solve loop woes

Edited by the Engineeringtalk editorial team Nov 20, 2003

Omniterm LPI and LPX current repeaters are designed to isolate instrument current loops from circulating ground currents that can cause system inaccuracies, or at worst instrument failure.

Instrumentation loop problems are frustrating at the best of times, and downright time consuming affairs for plant maintenance staff to deal with.

Most problems relate to isolation and ground faults, some of which present themselves intermittently or are hidden so deep in the plant wiring that tracing them becomes a full time job.

Omniflex's Omniterm range of DIN rail mount loop isolators use advanced electronic techniques to address the common problems associated with instrumentation loops using several specialised new products.

The Omniterm LPI and LPX are current repeaters specifically designed to isolate instrument current loops from circulating ground currents that can cause system inaccuracies, or at worst instrument failure.

The current applied to the input is repeated on the isolated output, and the load on the output is reflected back to the input.

No separate power source is required.

These second-generation products use advanced electronic techniques to achieve high accuracy with minimum loops losses and zero field calibration.

The LPI is optimised for lowest volt drop over 4-20mA, whereas the LPX is optimised for use with an extended current range from 0-50mA and load impedances down to zero ohms.

The Omniterm LPR current loop repeater and LPS current loop splitter products are specifically designed to create additional current loop signals from an existing current loop signal with minimal effect on the impedance of the existing loop.

The LPR has a single isolated output, whereas the LPS has two isolated outputs.

These 24V DC powered modules accept a 0-20 or 4-20mA input and create 0-20 or 4-20mA outputs.

The output current loops repeat the input signal and are isolated from the input signal and 24V DC power supply.

Impedance changes on the output loops have no effect on the input loop.

The module input is fully differential allowing the input to be connected anywhere in the input loop.