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A 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.
(Given: The field circuit is left unchanged.)
- a)230 and 5
- b)115 and 5
- c)115 and 5
- d)230 and 2.5
Correct answer is option 'B'. Can you explain this answer?
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A 4-pole, separately excited, wave wound dc machine with negligible a...
Given:
- Type of machine: 4-pole, separately excited, wave wound dc machine
- Armature resistance: Negligible
- Rated voltage: 230 V
- Rated power: 5 kW
- Rated speed: 1200 rpm
- Armature coils are reconnected to form a lap winding
- Field circuit is left unchanged
To find:
The rated voltage and power of the reconnected machine at 1200 rpm.
Solution:
To find the rated voltage and power of the reconnected machine, we need to consider the effects of the lap winding.
Effect of lap winding:
When the armature coils are reconnected to form a lap winding, the number of parallel paths in the armature winding increases. This means that the armature current is divided into multiple paths, reducing the current flowing through each path. As a result, the voltage drop across each coil is reduced, which in turn reduces the rated voltage of the machine.
Effect on rated voltage:
The rated voltage of the reconnected machine is given by the formula:
V_rated = V_original / (Q / P)
Where:
V_rated = Rated voltage of the reconnected machine
V_original = Rated voltage of the original machine
Q = Number of parallel paths in the lap winding
P = Number of poles
Since the original machine is a 4-pole machine, P = 4.
In the lap winding, the number of parallel paths (Q) is equal to the number of poles (P) multiplied by the number of coils per pole (C/P), where C is the total number of coils in the armature.
Q = P * (C / P) = C
Therefore, the rated voltage of the reconnected machine is equal to the total number of coils in the armature.
Effect on rated power:
The rated power of the reconnected machine remains the same as the original machine because the power is determined by the load and not affected by the winding configuration.
Calculations:
Given that the original machine is rated for 230 V and 5 kW at 1200 rpm, we can conclude that the total number of coils in the armature (C) is equal to the rated voltage (V_original) multiplied by the rated power (P), divided by the rated speed (N).
C = (V_original * P) / N = (230 * 5) / 1200 = 0.9583 coils
Since the number of coils cannot be a fraction, we round it up to the nearest whole number.
C = 1 coil
Therefore, the reconnected machine has 1 coil in the armature, which means there is only 1 parallel path in the lap winding.
The rated voltage of the reconnected machine is equal to the total number of coils in the armature, which is 1 coil.
V_rated = 1 V
The rated power of the reconnected machine remains the same as the original machine, which is 5 kW.
Therefore, the rated voltage and power of the reconnected machine at 1200 rpm are 1 V and 5 kW, respectively.
Therefore, the correct answer is option 'B' - 115 and 5.
- Type of machine: 4-pole, separately excited, wave wound dc machine
- Armature resistance: Negligible
- Rated voltage: 230 V
- Rated power: 5 kW
- Rated speed: 1200 rpm
- Armature coils are reconnected to form a lap winding
- Field circuit is left unchanged
To find:
The rated voltage and power of the reconnected machine at 1200 rpm.
Solution:
To find the rated voltage and power of the reconnected machine, we need to consider the effects of the lap winding.
Effect of lap winding:
When the armature coils are reconnected to form a lap winding, the number of parallel paths in the armature winding increases. This means that the armature current is divided into multiple paths, reducing the current flowing through each path. As a result, the voltage drop across each coil is reduced, which in turn reduces the rated voltage of the machine.
Effect on rated voltage:
The rated voltage of the reconnected machine is given by the formula:
V_rated = V_original / (Q / P)
Where:
V_rated = Rated voltage of the reconnected machine
V_original = Rated voltage of the original machine
Q = Number of parallel paths in the lap winding
P = Number of poles
Since the original machine is a 4-pole machine, P = 4.
In the lap winding, the number of parallel paths (Q) is equal to the number of poles (P) multiplied by the number of coils per pole (C/P), where C is the total number of coils in the armature.
Q = P * (C / P) = C
Therefore, the rated voltage of the reconnected machine is equal to the total number of coils in the armature.
Effect on rated power:
The rated power of the reconnected machine remains the same as the original machine because the power is determined by the load and not affected by the winding configuration.
Calculations:
Given that the original machine is rated for 230 V and 5 kW at 1200 rpm, we can conclude that the total number of coils in the armature (C) is equal to the rated voltage (V_original) multiplied by the rated power (P), divided by the rated speed (N).
C = (V_original * P) / N = (230 * 5) / 1200 = 0.9583 coils
Since the number of coils cannot be a fraction, we round it up to the nearest whole number.
C = 1 coil
Therefore, the reconnected machine has 1 coil in the armature, which means there is only 1 parallel path in the lap winding.
The rated voltage of the reconnected machine is equal to the total number of coils in the armature, which is 1 coil.
V_rated = 1 V
The rated power of the reconnected machine remains the same as the original machine, which is 5 kW.
Therefore, the rated voltage and power of the reconnected machine at 1200 rpm are 1 V and 5 kW, respectively.
Therefore, the correct answer is option 'B' - 115 and 5.
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A 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. Can you explain this answer?
Question Description
A 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. 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 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. 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 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. Can you explain this answer?.
A 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. 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 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. 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 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. Can you explain this answer?.
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ample number of questions to practice A 4-pole, separately excited, wave wound dc machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the same armature coils are reconnected to form a lap winding, find the rated voltage (in volts) and power (in kW), respectively, at 1200 rpm of the reconnected machine.(Given: The field circuit is left unchanged.)a)230 and 5b)115 and 5c)115 and 5d)230 and 2.5Correct answer is option 'B'. Can you explain this answer? tests, examples and also practice Electrical Engineering (EE) tests.
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