Labour Officer • 2026 • Paper-II
The ratio of the primary to secondary voltage of a transformer is 2:1. The saving in terms of weight of copper required if an autotransformer is used instead of a two-winding transformer will be:
A)
50%
B)
33.33%
C)
66.67%
D)
97%
Option B is correct: 33.33%.
Labour Officer • 2026 • Paper-II
Voltage control in power systems is mainly achieved using:
A)
Circuit breakers
B)
Tap changing transformers
C)
Fuses
D)
Lightning arresters
Option B is correct: Tap changing transformers.
Labour Officer • 2026 • Paper-II
Load frequency control ensures:
A)
Constant voltage
B)
Constant frequency
C)
Constant power factor
D)
Maximum fault current
Load Frequency Control (LFC) is a system used in power system operation to maintain the system frequency at a specified value (e.g., 50 Hz or 60 Hz) and to maintain the scheduled power exchange between different control areas.
1. **Mechanism**: In a power system, the frequency is directly linked to the balance between total power generation and total load demand. If generation exceeds demand, the frequency increases; if demand exceeds generation, the frequency decreases. LFC adjusts the mechanical power input to the generators (via governor control) to balance this equation and keep the frequency constant.
2. **Why other options are incorrect**:
- **Option a (Constant voltage)**: Voltage is maintained by Automatic Voltage Regulators (AVR) and reactive power compensation (like capacitor banks or SVCs), not by LFC.
- **Option c (Constant power factor)**: Power factor is managed by controlling the reactive power flow at the load or generation end, not by frequency control.
- **Option d (Maximum fault current)**: Fault currents are determined by the system impedance and the nature of the fault; they are not 'ensured' or controlled by LFC, which is a steady-state/dynamic stability control mechanism.
Labour Officer • 2026 • Paper-II
Define load factor, capacity factor, and diversity factor.
Labour Officer • 2026 • Paper-II
State rules for block diagram reduction technique.
Labour Officer • 2026 • Paper-II
The phenomenon of squirrel-cage motors sometime showing a tendency to run at a very low speed is known as:
A)
cogging
B)
crawling
C)
damping
D)
skewing
Option B is correct: crawling.
Labour Officer • 2026 • Paper-II
The skin effect in transmission lines causes:
A)
Increase in inductance
B)
Increase in resistance
C)
Decrease in capacitance
D)
Decrease in voltage
Option B is correct: Increase in resistance.
Labour Officer • 2026 • Paper-I
Digital instruments generally have:
A)
Lower accuracy
B)
Higher accuracy
C)
No sensitivity
D)
No stability
Digital instruments generally provide higher accuracy because they display measurements in discrete numerical form, reducing reading errors such as parallax and estimation errors that are common in analog instruments. Option (a) is incorrect because digital instruments are usually more accurate, not less. Option (c) is incorrect because digital instruments do have sensitivity to small changes in input. Option (d) is incorrect because digital instruments can be stable and are often designed for reliable readings.
Labour Officer • 2026 • Paper-I
Discuss ferromagnetism and ferrimagnetism with suitable examples and magnetic domain explanation.
Labour Officer • 2026 • Paper-I
Mesh analysis is applicable to:
A)
Non-planar circuits only
B)
Planar circuits
C)
AC circuits only
D)
DC circuits only
Mesh analysis can be applied only to planar circuits, i.e., circuits that can be drawn on a plane without any branches crossing. This is because mesh currents are defined for the smallest loops in a planar network. It is not limited to AC or DC circuits; it works for both, as long as the circuit is planar. Non-planar circuits do not have well-defined meshes, so option (a) is incorrect.
Labour Officer • 2026 • Paper-I
Ampere’s circuital law relates magnetic field intensity to:
A)
Electric potential
B)
Electric flux
C)
Electric current
D)
Magnetic flux
Ampere’s circuital law states that the line integral of magnetic field intensity around a closed path is equal to the electric current enclosed by that path. Therefore, it directly relates magnetic field intensity to electric current. Electric potential and electric flux are not involved in Ampere’s law, and magnetic flux is related more to Faraday’s law.
Labour Officer • 2026 • Paper-I
In free space, electromagnetic waves are:
A)
Longitudinal
B)
Transverse
C)
Circular
D)
Random
In free space, an electromagnetic wave has electric field (E) and magnetic field (B) oscillating perpendicular to each other and also perpendicular to the direction of propagation. Hence, it is a transverse wave. Longitudinal waves have oscillations parallel to propagation, which is not the case here. Circular and random do not describe the basic nature of EM waves in free space.
Labour Officer • 2026 • Paper-I
In a 3-phase power measurement by two wattmeter method, both the watt meters had identical readings. The power factor of the load was:
A)
Unity
B)
0.8 lagging
C)
0.8 leading
D)
zero
In the two-wattmeter method for a balanced 3-phase load, the wattmeter readings are equal when the load power factor angle is 0°. That means the current is in phase with the voltage, so the power factor is 1 (unity). For any lagging or leading power factor other than unity, the two readings will differ.
Labour Officer • 2026 • Paper-I
For the given network find the branch current in 8Ω and voltage across the 3Ω by applying KVL.
Labour Officer • 2026 • Paper-I
Velocity of EM wave in free space is:
A)
3×106 m/s
B)
3×108 m/s
C)
3×1010 m/s
D)
3×104 m/s
The velocity of an electromagnetic wave in free space is equal to the speed of light, which is approximately 3 × 10^8 m/s. Option (a) is too low, option (c) is too high, and option (d) is far too low.
Labour Officer • 2026 • Paper-I
The natural response of a circuit depends on:
A)
External excitation
B)
Stored energy in reactive elements
C)
Load resistance
D)
Source voltage
The natural response of a circuit is the response that occurs when all independent sources are removed. It is determined by the energy initially stored in reactive elements like inductors and capacitors. Therefore, the circuit’s natural response depends on stored energy in reactive elements, not on external excitation, load resistance, or source voltage.
Labour Officer • 2026 • Paper-I
Explain the operating principle of PMMC instruments.
Labour Officer • 2026 • Paper-I
Explain superconductivity, its properties, and applications in electrical engineering.
Labour Officer • 2026 • Paper-I
Explain the measurement of capacitance using Schering bridge.
Labour Officer • 2026 • Paper-I
Describe the working principle of Analog to Digital Converter.
Labour Officer • 2026 • Paper-I
The Maxwell bridge is used for measurement of:
A)
Resistance
B)
Capacitance
C)
Inductance
D)
Frequency
The Maxwell bridge is an AC bridge used to measure an unknown inductance by comparing it with a known capacitance and resistances. It is especially suitable for measuring medium-quality inductors.
Why not the others?
- Resistance is measured by Wheatstone bridge.
- Capacitance is measured by De Sauty bridge or Schering bridge.
- Frequency is not the primary quantity measured by Maxwell bridge.
Therefore, the correct answer is Inductance.
Labour Officer • 2026 • Paper-I
Flow rate in pipes is commonly measured using:
A)
Flow meter
B)
Wattmeter
C)
Voltmeter
D)
Ammeter
Flow rate in pipes is measured using a flow meter, which is specifically designed to measure the quantity of fluid flowing through a pipe per unit time. A wattmeter measures electrical power, a voltmeter measures voltage, and an ammeter measures electric current, so these are not suitable for pipe flow measurement.
Labour Officer • 2026 • Paper-I
A balanced delta connected load has, phase impedance = 10 Ω, line voltage = 400 V. Phase current is:
A)
23 A
B)
40 A
C)
69 A
D)
80 A
For a delta-connected load, phase voltage equals line voltage: Vph = VL = 400 V. The phase current is Iph = Vph / Zph = 400 / 10 = 40 A. However, the option that matches 40 A is (b), not (a). If the question intended line current, then IL = √3 × Iph = 1.732 × 40 ≈ 69 A, which matches option (c). Since the question specifically asks for phase current, the correct value is 40 A, so option (b) is correct.
Labour Officer • 2026 • Paper-I
Explain the properties of electric field inside conductors under electrostatic conditions.
Labour Officer • 2026 • Paper-I
The steady-state response of a circuit refers to:
A)
Initial condition
B)
Transient state
C)
Long-term behavior
D)
Zero response
The steady-state response is the part of the circuit response that remains after all transient effects have died out. It describes the circuit’s long-term behavior as time becomes large.
- (a) Initial condition: This relates to the circuit state at the beginning, not steady state.
- (b) Transient state: Transients are the temporary changes before steady state is reached.
- (c) Long-term behavior: Correct, because steady-state response is what persists in the long run.
- (d) Zero response: Zero-input or zero-state response are specific components, not the definition of steady state.
So, the correct answer is long-term behavior.
