🔍 Key Concepts
• Trace the control circuit in figure A from X1 to X2 and note which devices are in series (Stop, Start, coil, overloads).
• With a voltmeter referenced to X2 (grounded side of the secondary), points that are electrically connected (no open between them) should show the same voltage.
• Consider how voltage readings change across an open contact versus across a closed contact when the circuit is energized and the pushbuttons are operated.
💭 Think About
• With the start button depressed, which terminals in the circuit should be at the same potential as X1 if all series devices are good? Compare that expectation with the given readings at 1, 2, and 3.
• If you measure 115 VAC from a point to X2 on one side of a device, but 0 VAC on the other side (still to X2), what does that say about the condition of that device?
• Looking at the answer choices, which component, if open, would explain seeing 115 VAC at terminal 2 but 0 VAC at terminal 3 when the start button is pressed?
✅ Before You Answer
• Verify which contact (Stop or Start) is normally closed (NC) and which is normally open (NO) in the drawing.
• Confirm that X1, 1, and 2 should all be at the same voltage when the relevant contacts are closed; then decide whether terminal 3 should also be at that same voltage with the start button pressed.
• Before choosing, mentally ‘open’ each component in the answer choices (fuse, transformer secondary, stop, start) and see which one alone produces the exact pattern: 115 VAC at X1/1/2 and 0 VAC at 3.