The RCU220KN is a panel-mounting earth fault indicator: a signal unit that gives a visible red indication when an associated earth fault relay detects a fault, so the condition is shown at the board front rather than only on the relay itself or in a control system. It accepts a wide operating voltage of 12 to 230 V AC, which is what allows it to be driven either from a relay's low-voltage annunciator output or directly from a mains auxiliary supply. It has a single red flat lens, screw terminals and IP20 protection. Manufactured in Spain and supplied under the Function brand. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.