Podcast
Questions and Answers
In a delta connection, what is the relationship between line voltage and phase voltage?
In a delta connection, what is the relationship between line voltage and phase voltage?
- Line voltage is equal to the phase voltage. (correct)
- Line voltage is √3 times the phase voltage
- Line voltage is zero
- Line voltage is 1/√3 times the phase voltage
What quantity is measured when determining phase voltage?
What quantity is measured when determining phase voltage?
- Between line and neutral
- Between line and phase
- Between line and line
- Between phase and neutral (correct)
Which instrument is used to determine the power factor of a circuit?
Which instrument is used to determine the power factor of a circuit?
- Phase sequence indicator
- Ammeter
- Power factor meter (correct)
- Voltmeter
How is the neutral point achieved in a three-phase system?
How is the neutral point achieved in a three-phase system?
How many degrees represent one complete cycle?
How many degrees represent one complete cycle?
In a balanced three-phase system, what is the phase difference between the phase voltages?
In a balanced three-phase system, what is the phase difference between the phase voltages?
Which transformer connection is preferred for 3-phase, 4-wire service?
Which transformer connection is preferred for 3-phase, 4-wire service?
The energy in a star-delta combination is given by which expression, where $V_L$ is line voltage, $I_L$ is line current, and $\emptyset$ is the phase angle?
The energy in a star-delta combination is given by which expression, where $V_L$ is line voltage, $I_L$ is line current, and $\emptyset$ is the phase angle?
In a three-phase star-connected load, how is the line current related to the phase current?
In a three-phase star-connected load, how is the line current related to the phase current?
Which of the following combination doesn't have common neutral point?
Which of the following combination doesn't have common neutral point?
Flashcards
Delta Connection Current Relationship
Delta Connection Current Relationship
In a delta connection, Line current = √3 Phase current
Neutral Point Achievement
Neutral Point Achievement
Star connection allows for a neutral point, unlike delta connections.
Degrees in One Full Cycle
Degrees in One Full Cycle
360 degrees
Phase Difference in 3-Phase System
Phase Difference in 3-Phase System
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Neutral Current (Balanced System)
Neutral Current (Balanced System)
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Neutral Point in Delta Connection
Neutral Point in Delta Connection
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Bird on a high voltage power Line
Bird on a high voltage power Line
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Phase Voltage Measurement
Phase Voltage Measurement
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Neutral Wire Current
Neutral Wire Current
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Study Notes
- The provided text is about polyphase AC theory and includes multiple-choice questions (MCQs) for technician electricians in both Hindi and English.
Delta Connection
- In a delta connection, line current = √3 phase current.
Neutral Achievement
- A neutral is achieved by a star connection.
Phase Voltage Measurement
- Phase voltage can be measured between a line and neutral.
Power Factor Determination
- The power factor of a circuit can be determined by a power factor meter.
Phase Representation of a Full Cycle
- 360 degrees of phase represents one full cycle.
Phase Voltage Difference in a 3-Phase System
- The phase voltage differs by 120° in a 3-phase system.
Best Transformer Connection
- The best transformer connection for 3-phase, 4-wire services is delta-star.
Energy in Star-Delta Combination
- Energy in a star-delta combination is given by √3 VL x IL cos Ø.
Scott Combination Conversion
- Three phase to two phase can be converted into single phase supply.
Current in Neutral Wire
- The current in the neutral is zero when the three-phase load is balanced in a three-phase quadrilateral (4-wire system).
Three-Phase Balanced Star Connection
- With a three-phase balanced star connection, phase voltage = Line voltage /√3.
Three-Phase Star-Connected Load
- In a three-phase star-connected load, the line current is equal to the phase current.
Line Voltage in Three-Phase Star-Connected System
- In a three-phase star-connected system, the line voltage is equal to 1.732 times its phase voltage .
Relationship of Voltages in a Three-Phase Power System
- With a three-phase power system, the three voltages E, E, and E have the same magnitude and are displaced from each other at 120°.
Combination with a Common Neutral Point
- A star-delta combination has a common neutral point.
Neutral Wire in Star Connection
- In a star connection, the neutral wire is taken from the common point.
Current in Neutral of Three-Phase Star
- In a three-phase star connected to a balanced load, the current in the neutral is zero.
Bird on a Conducting Wire
- A bird sitting on a conducting wire (line) of a three-phase current carrying line is safe.
Color Codes for Conductors
- According to the Electric Code, the following colors are used for conductors: Phase – Red, Neutral – Green, Earth – Black.
Phase Voltage
- Phase voltage can be measured between Line and neutral
Current in Neutral Wire of Star
- In a balanced, 3 phase star connected system, 1 ampere of current flows through each phase, then the electric current in the neutral wire will be zero.
Three-Phase System Without Neutral
- The three-phase system that does not contain neutral is delta.
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