As shown in the illustrated reduced voltage three phase squirrel cage induction motor controller, what is the functional purpose of the "R" contactor? See illustration EL-0116.
• Wye-delta starting sequence: which contactors are closed during START, TRANSITION, and RUN • How the motor leads T1–T6 are connected to form wye versus delta in this diagram • Role of the R contactor and resistors in changing from reduced-voltage to full-voltage operation
• Identify which contacts (M, S1, S2, R) are energized immediately after you press START, and how that connects the motor windings • During the transition period (when the timer CR(TC) operates), which contactors must change state so the motor moves from wye to delta without being disconnected from the line? • When the motor is in its final RUN condition, trace whether current still passes through any resistors or only through solid contactor paths
• On the power diagram, carefully trace the path from L1, L2, L3 to T1–T6 with R open and then with R closed • Confirm in which periods (START, TRANSITION, RUN) the R coil is energized by reading the control diagram at the bottom • Be sure whether R is associated with the delta connection, the wye connection, or only with inserting/removing resistors during a specific period
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