The Siemens 3VA9377-0TB10 is a SENTRON COM060 communication module — an accessory that snaps into the right switch pocket of a 3VA6 400/600 molded-case circuit breaker or a COM800 system, adding four slots for communication and measurement functions. It draws a maximum of 0.1 A from the breaker's internal supply and dissipates 2.4 W, so the thermal budget inside the enclosure barely moves — no derating concern for adjacent devices. The module powers the electronic trip unit and exchanges data with it, detects the breaker's switch position (On, Off, Tripped), and communicates with residual-current equipment — all over a single spur line via T-feeder, with a total bus length of 20 m.
Mounts in the right switch pocket of the breaker — no DIN rail required, no extra wiring for the backplane. The 33 mm depth and 29 mm width keep it inside the breaker's own envelope, so the panel layout stays unchanged. Rated IP20 per IEC 60529, pollution degree 3, overvoltage category I, and operating resource protection class III per IEC 61558 — suitable for standard industrial control panels where the breaker itself provides the enclosure seal.