What it is and what it guards
The RM4JA32Q is a Harmony current measurement relay from Schneider Electric — it watches for overcurrent or undercurrent conditions on a monitored line and trips its output contacts when the measured current crosses the set threshold. It covers six measurement ranges: 1–5 A AC/DC, 3–15 A AC/DC, and 300–1500 mA AC/DC, so it fits motor feeder monitoring, pump protection, or heater circuit supervision in a single device. Two C/O (changeover) relay contacts give you both a normally-open and normally-closed signal path per channel — enough to drive an alarm and a trip in the same relay.
Setting the trip point and delay
The adjustable time delay from 0.05 to 30 seconds lets you ride through inrush or transient events before the relay trips — critical for motor start-up or transformer energisation where a short overcurrent is normal. The output relay trips when measured current exceeds the set threshold (overcurrent) or falls below it (undercurrent), configurable by the front-panel dials. Maximum measuring cycle is 80 ms, so the relay responds fast enough for most protection schemes without nuisance tripping on sub-cycle noise.
Panel fit and environmental tolerance
The RM4JA32Q measures 80 mm deep, 45 mm wide, and 78 mm high — a compact DIN-rail footprint that fits standard control-panel enclosures without crowding adjacent devices. IP20 on the terminals and IP50 on the casing means it's protected against dust ingress inside a panel but not for washdown environments — keep it in a sealed cabinet. Screw terminals accept 1.5 mm² flexible with cable end or 2.5 mm² flexible without — standard for panel wiring up to 14 AWG.