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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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We connect Centrifugal switch (CS) in series with auxiliary (starting) winding to _______________ and its ____________ type switch.
connect it after the starting period, NC
disconnect it after the starting period, NO
connect it after the starting period, NO
disconnect it after the starting period, NC
disconnect it after the starting period, NC
Quick Trick: Remember the core function of a Centrifugal Switch (CS) in single-phase motors: its job is to cut off (disconnect) the starting winding after reach ~75% speed, and it is normally closed (NC) at rest to allow initial current flow.
Remember the core function of a Centrifugal Switch (CS) in single-phase motors: its job is to cut off (disconnect) the starting winding after reach ~75% speed, and it is normally closed (NC) at rest to allow initial current flow.
Determine Function of Centrifugal Switch
The primary role of a centrifugal switch in a single-phase induction motor is to disconnect the auxiliary (starting) winding once the motor accelerates to approximately 70% to 80% of its rated speed. Thus, the first blank requires 'disconnect it after the starting period'.
Identify Switch Type (Initial State)
To allow current to flow through the starting winding when power is first applied, the switch contacts must be in a closed state initially. Therefore, it is a Normally Closed (NC) type switch at rest.
A: Wrong because the switch disconnects, not connects, and is NC, not NO. B: Wrong because although it disconnects, the switch is Normally Closed (NC), not Normally Open (NO). C: Wrong because it disconnects and is NC.
D is correct because a centrifugal switch is used to disconnect the starting winding after the motor reaches target speed and must be Normally Closed (NC) at stationary position.
Watch out for initial contact conditions vs. running conditions: switches that need to conduct at startup must be normally closed (NC) before motion begins.