Line protection MCCB with TM240 release
The Siemens SENTRON 3VA1140-5EF36-0DA0 is a 3-pole molded case circuit breaker (MCCB) rated for 40 A continuous current at up to 50 °C ambient, with the TM240 thermal-magnetic overcurrent release. It carries an interrupting capacity of 187 kA at 240 V, 121 kA at 415 V, and 75.6 kA at 440 V — figures that cover high-fault utility feeds and transformer secondaries without cascading upstream.
SCCR headroom and selectivity planning
The TM240 release has no electronic adjustment, so coordination studies rely on the fixed thermal-magnetic curve; the manufacturer publishes time-current curves for the 3VA series. The 15000-cycle latching endurance is typical for a distribution MCCB — adequate for infrequent switching, not for motor-starting duty cycles.
The 3VA1140-5EF36-0DA0 measures 76.2 mm wide, 130 mm high, and 70 mm deep. No auxiliary contacts are present on this variant, so status feedback to a PLC requires an add-on module.
Above 50 °C, derating applies: 38.4 A at 55 °C, 37.6 A at 60 °C, 36.8 A at 65 °C, and 36 A at 70 °C (–). The TM240 release's thermal element responds to self-heating plus ambient — a panel with poor airflow at 60 °C must be loaded to no more than 37.6 A.