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A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage induction motor has following equivalent circuit parameters per phase referred to the stator:R1 = 0.3Ω, R2 = 0.3Ω, X1 = 0.41Ω, X2 = 0.41Ω. Neglect shunt branch in the equivalent circuit. The starting current (in Ampere) for this motor when connected to an 80 V (line), 20 Hz, 3-phase AC source is __________.
Correct answer is between '69,71'. Can you explain this answer?
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A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage ...
Reactance offered by stator and Rotor will be changes, because of change in frequency.
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A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage ...
Starting current in an induction motor is higher than its rated current due to the high impedance of the rotor windings at standstill. To determine the starting current of the motor, we need to calculate the equivalent impedance of the motor at the given frequency and voltage.
Given Data:
- Power rating of the motor, P = 12.5 kW
- Line voltage, V = 208 V
- Frequency, f = 60 Hz
- Equivalent circuit parameters per phase referred to the stator: R1 = 0.3, R2 = 0.3, X1 = 0.41, X2 = 0.41
- Supply voltage during starting, Vs = 80 V
- Starting frequency, fs = 20 Hz
Calculating Equivalent Impedance:
The equivalent impedance per phase (Zeq) of the motor at the given frequency and voltage can be calculated using the following formula:
Zeq = R1 + jX1 + (R2 / s) + j(X2 / s)
Where:
- s = fs / f = 20 / 60 = 1/3 (slip)
Zeq = 0.3 + j0.41 + (0.3 / 1/3) + j(0.41 / 1/3)
= 0.3 + j0.41 + 0.9 + j1.23
= 1.2 + j1.64 (ohms)
Calculating Starting Current:
The starting current (Is) can be calculated using Ohm's law:
Is = Vs / |Zeq|
Where:
- Vs = 80 V (supply voltage during starting)
- |Zeq| = magnitude of Zeq = sqrt(1.2^2 + 1.64^2) = sqrt(1.44 + 2.6896) = sqrt(4.1296) = 2.03 ohms
Is = 80 / 2.03
≈ 39.41 A
The starting current of the motor when connected to an 80 V, 20 Hz, 3-phase AC source is approximately 39.41 A.
The correct answer is between '69,71'. However, the calculated starting current is significantly lower than the given range. It is possible that there is an error in the calculation or additional information is required to determine the correct answer.
Given Data:
- Power rating of the motor, P = 12.5 kW
- Line voltage, V = 208 V
- Frequency, f = 60 Hz
- Equivalent circuit parameters per phase referred to the stator: R1 = 0.3, R2 = 0.3, X1 = 0.41, X2 = 0.41
- Supply voltage during starting, Vs = 80 V
- Starting frequency, fs = 20 Hz
Calculating Equivalent Impedance:
The equivalent impedance per phase (Zeq) of the motor at the given frequency and voltage can be calculated using the following formula:
Zeq = R1 + jX1 + (R2 / s) + j(X2 / s)
Where:
- s = fs / f = 20 / 60 = 1/3 (slip)
Zeq = 0.3 + j0.41 + (0.3 / 1/3) + j(0.41 / 1/3)
= 0.3 + j0.41 + 0.9 + j1.23
= 1.2 + j1.64 (ohms)
Calculating Starting Current:
The starting current (Is) can be calculated using Ohm's law:
Is = Vs / |Zeq|
Where:
- Vs = 80 V (supply voltage during starting)
- |Zeq| = magnitude of Zeq = sqrt(1.2^2 + 1.64^2) = sqrt(1.44 + 2.6896) = sqrt(4.1296) = 2.03 ohms
Is = 80 / 2.03
≈ 39.41 A
The starting current of the motor when connected to an 80 V, 20 Hz, 3-phase AC source is approximately 39.41 A.
The correct answer is between '69,71'. However, the calculated starting current is significantly lower than the given range. It is possible that there is an error in the calculation or additional information is required to determine the correct answer.
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A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage induction motor has following equivalent circuit parameters per phase referred to the stator:R1 = 0.3Ω, R2 = 0.3Ω, X1 = 0.41Ω, X2 = 0.41Ω. Neglect shunt branch in the equivalent circuit. The starting current (in Ampere) for this motor when connected to an 80 V (line), 20 Hz, 3-phase AC source is __________.Correct answer is between '69,71'. Can you explain this answer?
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A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage induction motor has following equivalent circuit parameters per phase referred to the stator:R1 = 0.3Ω, R2 = 0.3Ω, X1 = 0.41Ω, X2 = 0.41Ω. Neglect shunt branch in the equivalent circuit. The starting current (in Ampere) for this motor when connected to an 80 V (line), 20 Hz, 3-phase AC source is __________.Correct answer is between '69,71'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage induction motor has following equivalent circuit parameters per phase referred to the stator:R1 = 0.3Ω, R2 = 0.3Ω, X1 = 0.41Ω, X2 = 0.41Ω. Neglect shunt branch in the equivalent circuit. The starting current (in Ampere) for this motor when connected to an 80 V (line), 20 Hz, 3-phase AC source is __________.Correct answer is between '69,71'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A star-connected, 12.5 kW, 208 V (line), 3-phase, 60 Hz squirrel cage induction motor has following equivalent circuit parameters per phase referred to the stator:R1 = 0.3Ω, R2 = 0.3Ω, X1 = 0.41Ω, X2 = 0.41Ω. Neglect shunt branch in the equivalent circuit. The starting current (in Ampere) for this motor when connected to an 80 V (line), 20 Hz, 3-phase AC source is __________.Correct answer is between '69,71'. Can you explain this answer?.
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