A single-channel adjustable earth leakage relay. It measures the residual current — the difference between the current flowing out to a load and the current returning from it, which is only non-zero when some of it is escaping to earth — and signals a separate switching device to open, rather than breaking the circuit itself. That split is what lets it protect circuits far larger than a self-contained RCD could switch. Sensitivity is adjustable from 30 mA to 10 A and the tripping delay from 0 to 3 seconds, which together allow it to be set for genuine selectivity against devices downstream of it. It provides a 6 A change-over output contact and runs from a 230 V AC supply. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.