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. The 800 V rated insulation voltage (Ui) suits it for 690 V line-to-line systems where the 17 kA interrupting rating applies. This is a line-protection variant, not a motor-protector; the TM240 release provides fixed thermal and magnetic trip thresholds for feeder and distribution duty.
SCCR headroom and selectivity planning
For a site electrical engineer coordinating selectivity, the 187 kA at 240 V and 121 kA at 415 V ratings mean this MCCB can be applied downstream of a transformer with minimal let-through energy — the high interrupting capacity reduces the need for current-limiting fuses upstream. 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.
Panel integration and mounting
The 3VA1140-5EF36-0DA0 measures 76.2 mm wide, 130 mm high, and 70 mm deep. It mounts on a DIN rail or directly to a backplate via the screw terminals. The IP40 front protection means it is protected against tools and wires >1 mm — suitable for enclosed panel installation, not for washdown environments. The undervoltage release (UVR) is fitted as standard, so the breaker trips on loss of control voltage; the auxiliary trip accessory (3VA9608-0BB25) is available but not included. No auxiliary contacts are present on this variant, so status feedback to a PLC requires an add-on module.
Thermal derating and ambient limits
The 40 A rating holds flat from 40 °C to 50 °C. 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 operating ambient range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. For a panel builder, this means the breaker can be placed near heat-generating components (drives, transformers) as long as the ambient at the breaker's inlet stays within the derated current. 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.