What measurement is correct when the 24 V DC contactor activates a 3-phase AC motor?

When a 24 V DC contactor activates a 3-phase AC motor, the voltage measurements across the motor terminals correspond to the supply voltage of the 3-phase system. In a typical 3-phase system, the line-to-line voltage is often around 400 V. Therefore, measuring 400 V between terminal 1 and terminal 4 aligns with the expected voltage configuration for a 3-phase motor, which is generally connected in such a way that it receives the full line voltage when energized.

The measure of 400 V indicates a line-to-line voltage, which is the voltage that the motor effectively uses during operation. This is standard in many industrial settings, where the standard three-phase AC voltage is often at this level, especially in regions following European electrical standards. Such a measurement confirms the correct operation of the contactor and motor system under normal conditions.

In contrast, the other options do not reflect typical 3-phase voltage scenarios. Measurements such as 230 V, 300 V, and potential configurations like terminals 2 and 6 would not normally correspond to a standard AC power supply for a three-phase motor in this context. Thus, the correct measurement reaffirming proper electrical connections and operational standards for a 3-phase motor being activated by