As shown in the illustration of an...

Question 1 of 2921866636eed28f7522a1c51db4e

As shown in the illustration of an electrically operated watertight door controller, how is reversal of the direction of motor rotation achieved? Illustration EL-0115

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Question 1 of 29218

As shown in the illustration of an electrically operated watertight door controller, how is reversal of the direction of motor rotation achieved? Illustration EL-0115

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🔍 Key Concepts

• Examine how many separate windings the door motor has in this diagram and how they are connected to the supply when the OPEN and CLOSE contactors pick up. • Recall that for a DC motor, reversing rotation requires changing the polarity of either the field or the armature, but not both at the same time. • Look closely at which leads are actually swapped when the circuit changes from OPEN to CLOSE, and whether the series field, shunt field, or armature connections are the ones being interchanged.

💭 Think About

• When the OPEN pushbutton is pressed, which contacts close to feed the motor, and which motor leads go to L1 and L2? Sketch that connection. • When the CLOSE pushbutton is pressed, how do those same motor leads get reconnected? Are they simply swapped, or does only one part of the motor (field or armature) change polarity? • Ask yourself: in a series DC motor, what happens to direction if both the field and armature are reversed together versus only one of them being reversed?

✅ Before You Answer

• Verify from the diagram whether the motor is drawn with a series field (in line with the armature) or a shunt field (in parallel across the supply). • Trace the circuit for both the OPEN and CLOSE positions and mark which specific winding terminals change connection to L1 and L2. • Confirm whether the reversal is applied to only one winding set or to both field and armature together before choosing the option.