Measurement of Energy MCQ Quiz in मल्याळम - Objective Question with Answer for Measurement of Energy - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Last updated on Mar 11, 2025

നേടുക Measurement of Energy ഉത്തരങ്ങളും വിശദമായ പരിഹാരങ്ങളുമുള്ള മൾട്ടിപ്പിൾ ചോയ്സ് ചോദ്യങ്ങൾ (MCQ ക്വിസ്). ഇവ സൗജന്യമായി ഡൗൺലോഡ് ചെയ്യുക Measurement of Energy MCQ ക്വിസ് പിഡിഎഫ്, ബാങ്കിംഗ്, എസ്എസ്‌സി, റെയിൽവേ, യുപിഎസ്‌സി, സ്റ്റേറ്റ് പിഎസ്‌സി തുടങ്ങിയ നിങ്ങളുടെ വരാനിരിക്കുന്ന പരീക്ഷകൾക്കായി തയ്യാറെടുക്കുക

Latest Measurement of Energy MCQ Objective Questions

Top Measurement of Energy MCQ Objective Questions

Measurement of Energy Question 1:

A 230 V single-phase energy meter has a constant load current of 20 A at unity power factor. If the meter disc makes 2300 revolutions for 2 hours, the meter constant will be:

  1. 0.25 revolution/kWh
  2. 250 revolution/kWh
  3. 0.30 revolution/kWh
  4. 270 revolution/kWh

Answer (Detailed Solution Below)

Option 2 : 250 revolution/kWh

Measurement of Energy Question 1 Detailed Solution

Concept:

Meter constant \(= \frac{{no\;of\;revolution\;in\;1\;hr}}{{no\;of\;kw\;in\;1\;hr\;}}\)

Calculation:

Given, V = 230 volt

I = 20 amp at unity power factor

Power = VIcosϕ = 230 × 20 × 1 = 4600 watt = 4.6 kW

No of revolution in 1 hr = 2300/2 = 1150 revolution

Meter constant \(= \frac{{1150}}{{4.6}}\) = 250 revolution/kwh

Measurement of Energy Question 2:

Which energy meter system contains a rotating aluminium disc that is placed between the air gaps of series and shunt magnets and mounted on a shaft?

  1. Magnetic Flux
  2. Moving System
  3. Registering System
  4. Driving System

Answer (Detailed Solution Below)

Option 2 : Moving System

Measurement of Energy Question 2 Detailed Solution

Energy meter

  • Energy meter measures electrical energy in a kilowatt hour.
  • It is also known as kilowatt-hour meter or Induction type watt-hour meter.
  • It is a type of ''integrating instruments.''

 

F1 Jai 21.11.20 Pallavi D8

 

Component

Construction

Driving system

The components of this system are two silicon steel laminated electromagnet

Upper magnet→ Shunt magnet→ behave as potential coil

Lower magnet→ series magnet→ behave as current coil

Moving system

In this system a thin aluminum disk placed in the air gap between the two electromagnets and mounted on a vertical shaft which is free to rotate.

Registering system

It registers the number of rotation of the disk which is proportional to the energy consumed directly in kilowatt-hour

Braking system

This system has a permanent magnet called brake magnet. It is located near the disk so that eddy currents are induced and braking toque to the disk.

 

Measurement of Energy Question 3:

The adjustment of position of shading bands, in an energy meter is done to provide:

  1. Friction compensation
  2. Creep compensation
  3. Braking torque
  4. None of the given

Answer (Detailed Solution Below)

Option 1 : Friction compensation

Measurement of Energy Question 3 Detailed Solution

Friction Compensation (or) Friction Error:

  • Frictional forces at the rotor bearings and in the counting (or register) mechanism cause a noticeable error, especially at light loads.
  • At light loads, the torque due to friction adds considerably to the braking torque on the disc rotor.
  • Since friction torque is not proportional to the speed but is roughly constant it can cause a considerable error in meter reading.

 

Adjustment:

  • This error can be reduced by making the ratio of the shunt magnet flux φ2 and series magnet flux φ1 large with the help of two shading rings (or shading bands).
  • These bands embrace the flux contained in the two outer limbs of the shunt magnet and thus eddy currents are induced in them which cause a phase displacement between the enclosed flux and the main gap flux.
  • As a result, small driving torque is exerted on the disc rotor, this torque being adjusted by variation of the positions of these bands to compensate for friction in the instrument.
  • The correctness of friction compensation is achieved by running the meter at a high load of about 8 to 10% of full load when the disc should rotate correctly.
  • Overcompensation leads to creep. This adjustment is known as light load adjustment.

Measurement of Energy Question 4:

Consider the following statements:

Adjustment is required in an induction type energy meter in the following manner so that it can be compensated for the slow down of speed on the specified load due to some unspecified reason:

1) Adjusting the position of the braking magnet and moving it away from the center of the disc.

2) Adjusting the position of the braking magnet and moving it closer to the center of the disc.

3) Adjusting the load.

Which of these statements are correct?

  1. 1,2 and 3
  2. 1 only
  3. 2 only
  4. 3 only

Answer (Detailed Solution Below)

Option 2 : 1 only

Measurement of Energy Question 4 Detailed Solution

Energy meter:

F1 Jai 21.11.20 Pallavi D8

In an induction type energy meter, a braking magnet is used to control the speed of the rotating disc. The braking magnet interacts with the disc by producing eddy currents, which create an opposing torque to slow down the disc. If the energy meter slows down unexpectedly on a specified load, adjustments can be made by:

  • Adjusting the position of the braking magnet and moving it away from the center of the disc: 
    Correct: Moving the braking magnet away from the center reduces the braking torque, allowing the disc to rotate faster and compensate for the slowdown.
    Also, 

    \({T_B} \propto N\phi _m^2d\) ⇒ N ∝ 1 / d

  • Adjusting the position of the braking magnet and moving it closer to the center of the disc:
    Incorrect: Moving the magnet closer to the center increases the braking torque, further slowing down the disc, which is not desired if the meter is already running slow.
  • Adjusting the load:
    Incorrect: Adjusting the load does not compensate for the internal slowdown of the energy meter. The meter's performance should not depend on changing the external load conditions.

Measurement of Energy Question 5:

The permanent magnet in an a.c. energy meter provides:

  1. Damping torque
  2. Deflecting torque
  3. Breaking torque
  4. All of these

Answer (Detailed Solution Below)

Option 3 : Breaking torque

Measurement of Energy Question 5 Detailed Solution

In an AC energy meter, there are 4 types of system

Driving system:

Performed by 2 silicon steel laminated electromagnets.

Moving system:

Performed by aluminum disc, placed between these 2 electromagnets.

Braking system:

  • The main part of this system is a permanent magnet called brake magnet. 
  • It is located near the disk so that eddy currents are induced in it due to the movement of the rotating disk through the magnetic field.
  • This eddy current reacts with the flux and exerts a braking torque which opposes the motion of the disk.
  • The speed of the disk can be controlled by changing flux.

 

Registering system: 

It registers the number of rotations of the disk which is proportional to the energy consumed.

Measurement of Energy Question 6:

A Single Phase 250 V induction watthour meter has a meter constant of 400 revolutions per kWh. Determine the speed of the disc in rpm, for a current of 15 A at a unity power factor

  1. 400
  2. 250
  3. 25
  4. 50

Answer (Detailed Solution Below)

Option 3 : 25

Measurement of Energy Question 6 Detailed Solution

Formula Used:

Meter Constant (K) = \(\frac{R}{E}\)

Here, R is revolution per hour

E is energy in kWh

Application:

We have,

V = 250 volts

I = 15 A

In one hour,

Energy consumed (E) = (250 × 15 × 1) Wh = (250 × 15 × 10-3) kWh

K = 400

From above concept,

R = KE = 400 × (250 × 15 × 10-3) = 1500 rev/hour

Here question has concern with revolution in rpm.

Hence, R(rpm)\(\frac{1500}{60}=25\)

Measurement of Energy Question 7:

A 230-V, 50-A energy meter on full load test makes 61 revolutions in 37 seconds. If the meter constant is 520 rev/kwh, what is the percentage error?

  1. 0.67%
  2. 0.76%
  3. 1%
  4. 0.24%

Answer (Detailed Solution Below)

Option 2 : 0.76%

Measurement of Energy Question 7 Detailed Solution

Given that, current (I) = 50 A

Voltage (V) = 230 V

Time (t) = 37 seconds

Energy \(E = VIt = 230 \times 50 \times \frac{{37}}{{3600}} \times {10^{ - 3}} = 0.1182\;kWh\)

Meter constant, 1 kWh = 520 revolutions

Energy recorded by meter during the test period = 61/520 = 0.1173 kWh

Percentage error \(= \frac{{0.1173 - 0.1182}}{{0.1182}} \times 100 = -0.76\;\%\)

Measurement of Energy Question 8:

‘Creeping’ is a term related to _____ instruments.

  1. Dynamometer type
  2. PMMC type
  3. Induction type
  4. Moving iron type

Answer (Detailed Solution Below)

Option 3 : Induction type

Measurement of Energy Question 8 Detailed Solution

Creeping in the induction type energy meter is the phenomenon in which the aluminum disc rotates continuously when only the voltage is supplied to the pressure coil and no current flows through the current coil. It is the kind of error in which the energy meter consumes a very small amount of energy even when no load is attached to the meter.

The creeping increases the speed of the disc even under the light load condition which increases the meter reading. Vibration, stray magnetic field and the extra voltage across the potential coil are also responsible for the creeping.

The creeping error occurs because of excessive friction. The main driving torque is absent at no load. Hence the disc rotates because of the additional torque provided by the compensating vane.

Measurement of Energy Question 9:

If an energy meter makes 5 revolutions in 100 seconds, when a load of 225 W is connected, the meter constant is

  1. 800 rev/kWh
  2. 222 rev/kWh
  3. 147 rev/kWh
  4. 13 rev/kWh

Answer (Detailed Solution Below)

Option 1 : 800 rev/kWh

Measurement of Energy Question 9 Detailed Solution

Concept:

  • The number of revolutions made by the energy meter per kilowatt-hour is known as the meter constant of an energy meter.
  • Unit of meter constant is revolution per kilowatt-hour (rev/kWh)
  • It is constant for a particular energy meter.

 

Meter constant (K) = No. of revolution by meter / Energy consumed (E)

E (in kWh) = voltage x current x cos ϕ × time x 10-3 = Load × time x 10-3

Where, cos ϕ = power factor

Calculation:

Load power = 225 W, time = 100 sec, Number of revolutions = 5

Energy supplied in 100 seconds \(= 225 \times \frac{{100}}{{3600}} \times {10^{ - 3}} = 6.25 \times {10^{ - 3}}\;kWh\)

Number of revolutions in 100 seconds = 5

Meter constant = number of revolutions / kWh

Meter constant \( = \frac{5}{{6.25 \times {{10}^{ - 3}}}} = 800\;rev/kWh\)

Measurement of Energy Question 10:

The speed of the aluminum disc in an energy meter is controlled by __________.

  1. shunt and series magnets
  2. series magnet
  3. shunt magnet
  4. braking magnet 

Answer (Detailed Solution Below)

Option 4 : braking magnet 

Measurement of Energy Question 10 Detailed Solution

Energy meter

The meter which is used for measuring the energy utilized by the electric load is known as the energy meter. 

It is a type of integrating instrument.

Construction of Energy Meter

F1 Savita Engineering 10-5-22 D19

1.) Driving System 

  • The electromagnet is the main component of the driving system.
  • The driving system has two electromagnets. The upper one is called the shunt electromagnet, and the lower one is called the series electromagnet.
  • The series electromagnet is excited by the load current flow through the current coil.
  • The coil of the shunt electromagnet is directly connected with the supply and hence carries the current proportional to the shunt voltage. This coil is called the pressure coil.
  • The center limb of the magnet has a copper band. These bands are adjustable. The main function of the copper band is to align the flux produced by the shunt magnet in such a way that it is exactly perpendicular to the supplied voltage.

2.) Moving System

  • The moving system is the aluminum disc mounted on the shaft of the alloy.
  • The disc is placed in the air gap of the two electromagnets.
  • The eddy current is induced in the disc because of the change in the magnetic field. This eddy current is cut by the magnetic flux. The interaction of the flux and the disc induces the deflecting torque.
  • When the devices consume power, the aluminum disc starts rotating, and after some number of rotations, the disc displays the unit used by the load.

3.) Braking system

  • The permanent magnet is used for reducing the rotation of the aluminum disc. 
  • The braking torque opposes the movement of the disc, thus reducing its speed.
  • The permanent magnet is adjustable due to which the braking torque is also adjusted by shifting the magnet to the other radial position.

4.) Registration (Counting Mechanism)

  • The main function of the registration or counting mechanism is to record the number of rotations of the aluminum disc.
  • Their rotation is directly proportional to the energy consumed by the loads in the kilowatt hour.
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