A two-channel adjustable earth leakage relay with a pre-alarm. 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. Sensitivity is adjustable from 30 mA to 10 A and the tripping delay from 0 to 3 seconds. The distinguishing feature against the single-channel 1660560 is the pre-alarm at 50 % of the set threshold: it reports a circuit that is drifting toward a trip while it is still running, which turns a developing insulation fault into a planned repair instead of an unplanned outage. A 6 A change-over output contact is provided; supply is 230 V AC. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.