Question 1 of 292185eccefa4bacbc34ba4d48386

As shown in figure "A" of the illustrated automatic secondary resistance motor controller, at how many operating speeds does the motor run from start-up to rated speed? See illustration EL-0144.

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Question 1 of 29218
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Q

As shown in figure "A" of the illustrated automatic secondary resistance motor controller, at how many operating speeds does the motor run from start-up to rated speed? See illustration EL-0144.

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🔍 Key Concepts

• Secondary-resistance wound-rotor induction motor starting – each resistor step usually corresponds to a different running speed during acceleration • In figure A, note the contactors labeled 1S and 2S and the separate time relays TR1 and TR2 that cut out rotor resistance in steps • The motor runs through a sequence: full resistance in circuit, partial resistance, then no added resistance (rated speed condition)

💭 Think About

• Count how many distinct rotor-resistance conditions the motor passes through from the moment you press START until all automatic timing sequences are complete • Ask yourself: when each time relay (TR1 and TR2) operates, what changes in the rotor circuit, and does that create a new speed point? • Consider whether the initial condition (all resistance in) plus each subsequent contactor operation represent separate operating speeds

✅ Before You Answer

• Identify all positions of the rotor circuit: all resistance in, intermediate resistance, and all resistance out • Verify how many separate contactor / switch operations (1S, 2S) actually change the amount of resistance in the rotor, not just seal in the circuit • Make sure you count the initial starting condition as one of the speed points if the rotor resistance there is different from later steps