The 3UG4981-0C is a sealable cover from the Siemens SIRIUS family, designed specifically for the 3UG4581 and 3UG4582 insulation monitoring relays. It snaps onto a 22.5 mm wide relay housing and adds a tamper-proof seal over the front adjustment dials and wiring access — a common requirement on mining, water, and process lines where an inspector or authority needs to lock the setpoint after commissioning.
Mounts in any orientation, so it fits tight gland plates or vertical backplane runs without derating.