ABB CM-SFS.21S electrical relay

The CM-SFS.21S is a single-functional current monitoring relay from the CM single-phase monitors range. This monitoring relay operates with a rated control supply voltage of 24 - 240 V AC / DC and has a 2 c/o (SPDT) output with contacts rated at 250 V / 4 A. It provides a RMS measuring principle for DC and AC currents with 3 measuring ranges: 3-30 mA, 10-100 mA and 0.1-1 A. The CM-SFS.21S offers window (over- and undercurrent) monitoring as well as selection of ON- or OFF-delay, open- or closed-circuit operating principle, with or without latching function. The output contacts can be configured as 1x2 c/o (SPDT) (common signal) or 2x1 c/o (SPDT) (separate signal for minimum and maximum thresholds) operation. The hysteresis is fixed at 5 % of the threshold value. The tripping delay and the start-up delay are adjustable over a range of instantaneous to 30 s (0, 0.1-30 s). A sealable transparent cover for protection against unauthorized changes is available as accessory. The device offers screw connection technology with double-chamber cage connection terminals.