The LC3D115E7 is a TeSys D star delta starter from Schneider Electric, designed for motor control applications under AC-3 utilisation category. It is a pre-wired assembly with 3 x 3P (3 NO) power poles, rated at 115 A with a 48 V AC coil. This configuration is used to reduce inrush current during motor start-up by first connecting the motor windings in star configuration, then transitioning to delta for full-load running.
The 115 A rating under AC-3 duty means this starter is sized for switching squirrel-cage induction motors where the making current is typically 5–8 times the rated current, but breaking current is low — the contactor only interrupts the motor's running current, not the start surge. For a 400 V three-phase supply, 115 A AC-3 corresponds roughly to a 55 kW motor, though exact sizing depends on the motor's full-load current and duty cycle. The 48 V AC coil is a low-voltage control circuit standard, common in panels where safety extra-low voltage (SELV) is not required but a lower control voltage reduces shock risk and allows smaller control transformers. Coil pickup and dropout characteristics follow the TeSys D family curve — verify the control transformer can deliver the inrush VA at 48 V. Rated operational voltage is specified for the power circuit, and the signalling circuit is tested to 10 MOhm insulation resistance. The starter operates without derating up to 3000 m altitude, which covers most industrial sites outside high-altitude mining or mountain installations.
Mechanical and environmental robustness
The starter withstands vibrations of 2 Gn (5–300 Hz) when open and 4 Gn when closed, with shock resistance of 15 Gn for 11 ms when closed and 6 Gn for 11 ms when open. Protective treatment TH conforming to IEC 60068-2-30 indicates the starter is tested for damp heat cyclic conditions, meaning it can tolerate high-humidity environments common in food processing or textile plants without corrosion or insulation degradation.