What it is and what it does
The Siemens 3VM9214-0RS20 is a SENTRON RCD210 residual current protection module, type A, designed as a side-mounted accessory for 3VM basic breakers. It handles a rated operational current of 250 A at AC across 4 poles, with adjustable residual current settings from 0.03 A up to 5 A and a selectable non-tripping time delay from 0 to 3000 ms. That range covers both fast fault clearing for personnel protection and delayed coordination with downstream RCDs.
Where it fits and how it mounts
This module mounts via screw fixing to the side of a 3VM molded-case breaker. The infeed can land on either the top or bottom of the RCD component, which simplifies panel layout when busbar routing or cable entry dictates the feed direction. Front protection is IP40, so it's suited for enclosed panel mounting where dust ingress is minimal but not sealed against hose-down.
Key ratings and what they mean for your panel
The 250 A rating at AC matches the full-load current of a 3VM breaker frame, so this module doesn't derate the breaker's main path. The type A classification means it detects both sinusoidal AC residual currents and pulsed DC residual currents up to 6 mA — common in single-phase rectifier loads like switching power supplies and variable-speed drives. The pre-alarm indication at 30% of the set residual current gives an early warning before a nuisance trip shuts the line.
Physical footprint
Dimensions are 170 mm wide, 228 mm high, and 70 mm deep. That depth is the key clearance number when fitting this side-mounted module inside an enclosure — you need at least 70 mm of free space beside the breaker to accommodate the RCD body and cable connections.