The loads on 3 phase 4 wire distributors are usually

A. Balanced
B. Unbalanced
C. Either of the above
D. None of the above

Answer: B. Unbalanced

Explanation:

1-phase 2-wire: 

• In this, one of the two wires is earthed or the mid-point of phase winding is earthed.
• This system is used for very short distances

1-phase 3-wire: 

• This system is identical in principle to the 3-wire dc distribution system.
• The neutral wire is center-tapped from the secondary winding of the transformer and earthed.
• This system is also called a split-phase electricity distribution system

 

2-phase 3-wire: 

• In this system, the neutral wire is taken from the junction of two-phase windings whose voltages are in quadrature with each other.
• The voltage between the neutral wire and either of the outer phase wires is V whereas, the voltage between outer phase wires is √2V. 
• As compared to a two-phase 4-wire system, this system suffers from voltage imbalance due to unsymmetrical voltage in the neutral

3-phase 4-wire: 

• This system uses star-connected phase windings and the fourth wire or neutral wire is taken from the star point.
• If the voltage of each winding is V, then the line-to-line voltage (line voltage) is √3V and the line-to-neutral voltage (phase voltage) is V. 
• This type of distribution system is widely used in India for secondary distribution.
• Loads on 3 phase 4 wire distributors are usually unbalanced.

Power System MCQs With Explanation 

 

• The advantages of high transmission voltage are
• The charging current drawn by the cable is
• The fact that current density is higher at the surface when compared to the center is known as
• In which of the following transmission lines capacitance effect is negligible?
• The distribution constant of the transmission line is
• Proximity effect is more in case of
• If the frequency is increased, then the skin effect will
• Bundled conductors in EHV transmission lines help in
• Which of the following produces radio interference in communication lines?
• Telecommunication lines are transposed to reduce the
• What is the function of economizer in Thermal Power Plant 
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• Corona is accompanied by
• The conductor carries more current on the surface as compared to the core. This is called as
• Critical disruptive voltage is a voltage at which
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• Low power factor is usually not due to
• Bonding is done at both ends of the cable to reduce the
• For Improving power factor
• Stock bridge dampers are used to
• Which of the following insulator is practically used for railway crossings?
• Which of the following decides the insulation level of 400 kV, EHV line?
• When earth fault occurs
• The minimum length of pipe electrode used for earthing should not be less than
• A ground wire is used to
• Earth resistance in typical domestic wiring is
• By which of the following systems electric power may be transmitted?
• Which of the following equipment will be most economical for regulating the voltage in the distribution feeder?

Transformer MCQs With Explanation 

• In a transformer the primary flux is 
• The noise of the transformer is mainly due to
• Buchholz relay is used for the protection
• Iron loss in a transformer can be determined by
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• Minimum voltage regulation occurs in transformer when the power factor of the load is
• The chemical used in the breather of a transformer should have the property of
• The power transformer can be termed as a constant
• In a transformer, which of the following losses are zero?
• Which of the following Transformer can have a tap changer?
• If the supply frequency (f) of a transformer decreases, the effect of frequency on the transformer's secondary output voltage?
• The primary winding of a transformer has a 120 V ac supply. What is the value of secondary voltage if the turn ratio is 10?
• The efficiency of a power transformer is _____ at full load.
• In a transformer the relation between the input frequency and the output voltage on secondary winding is _____.
• In a current transformer, _____ winding is closed.
• A transformer is a _____ device.
• A step-down transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
• A step-up transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
• Transformer works on ______ principle.
• Shell Type Transformer is mainly used for 
• A Magnetic Oil level Guage (MOG) is used in the Transformer to 
• The Function Of Power Transformer is/are
• The Radiators are used in transformers for 

Synchronous Motor MCQs With Explanation 

• In 3 -Φ synchronous motor if one of the phases is short-circuited the motor will
• The speed regulation of a synchronous motor is
• The negative phase sequence in a three-phase synchronous motor exists when the motor is
• What happens if the field winding of the synchronous motor is short-circuited?
• For power factor correction, synchronous motors operate at

Induction Motor MCQs With Explanation 

• In a capacitor start and run the motor the function of the running capacitor in series with the auxiliary winding is to
• A split-phase motor has
• If the capacitor of a single-phase motor is short-circuited
• In a split-phase motor, the running winding should have