Overview
The REL21704 is a Schneider MiCOM P127 voltage/current protection relay rated 1 A nominal, with 4 current inputs accepting X/5 A and X/1 A CTs plus 3 voltage inputs, 12 discrete inputs, and 9 discrete outputs. It supports DNP3, IEC 60870-5-103, and Modbus RTU protocols, runs on a 250 V DC supply, and is flush-mounted with a 103.0 mm width and 270 mm total depth.
Lifecycle and sourcing
Schneider lists the REL21704 as discontinued; remaining units are sourced through surplus and broker channels rather than current distribution. For a BOM freeze or line-down situation, an RFQ confirms available quantity and lead time for this exact build code.
Comparison with REL21201
The REL21704 has 12 discrete inputs and 9 discrete outputs; the REL21201 has 3 discrete inputs and 7 discrete outputs. The REL21704 also adds voltage inputs (3 voltage) and a broader protection suite including ANSI 79 recloser, ANSI 27 undervoltage, ANSI 59 overvoltage, and directional elements not present on the REL21201.