What this 40 A MCCB does in a panel
The Siemens SENTRON 3VA2040-7KQ36-0AA0 is a 3-pole molded case circuit breaker rated for 40 A continuous current, with no derating required across its full operating range from -25 °C to 70 °C — it holds 40 A at every temperature step from 40 °C through 70 °C, so you don't lose capacity in a warm enclosure. The ETU860 electronic trip unit provides communication functionality, meaning this breaker can report status and trip events over a network — useful for a wind-turbine tower where climbing to read a mechanical flag costs time and risk. Interrupting capacity hits 330 kA at 240 V and 242 kA at 415 V — numbers that let you place this 40 A breaker deep in a high-fault-current distribution without worrying about cascading failure upstream.
Footprint and mounting
At 105 mm wide, 181 mm tall, and 86 mm deep, this breaker fits standard MCCB panel cutouts. The 86 mm depth leaves room behind the gland plate for wiring — no need to oversize the enclosure just to clear the back of the breaker. IP40 on the front face means it's protected against solid objects larger than 1 mm, but it's not sealed against moisture — mount it inside a weatherproof cabinet if the panel lives outdoors or in a nacelle.