MiCOM Alstom P541/P542 series provide high-speed current differential unit protection. The P541, P542 are designed for all overhead line and cable applications, interfacing readily with the longitudinal (end-end) communications channel between line terminals. The interface options support direct fibre optic or multiplexed digital links.

Optimum selectivity is assured, as the scheme measures the currents entering and leaving the protected plant item. Instantaneous tripping results for an internal fault, with stability for any out-of-zone fault. Tripping uses a proven characteristic comparing differential current with through current, for ease of testing. Phase differential elements of this type offer consistent detection of solid and resistive faults, with optimum faulted phase selection, tripping, and indication. 

Basic description:

• Line differential protection with overcurrent backup protection and autoreclose
• Application fields: distribution lines and cables