Q.1 Which communication protocol is specifically designed for real‑time data exchange in power system automation?
MQTT
Modbus TCP
IEC 61850
CoAP
Explanation - IEC 61850 defines a set of standards for communication within substations, providing high‑speed, real‑time data exchange for protection, control, and monitoring.
Correct answer is: IEC 61850
Q.2 In a smart grid, which wireless technology typically operates in the 2.4 GHz ISM band and supports mesh networking for low‑power devices?
ZigBee
Wi‑MAX
Bluetooth LE
LTE‑Advanced
Explanation - ZigBee is a low‑power, low‑data‑rate wireless protocol that uses the 2.4 GHz ISM band and can form self‑healing mesh networks, making it suitable for smart meters and sensors.
Correct answer is: ZigBee
Q.3 Which of the following is a key advantage of Power Line Communication (PLC) in smart grid applications?
Unlimited bandwidth
Utilizes existing electrical wiring
Zero latency
Operates without any interference
Explanation - PLC leverages the existing power cables for data transmission, reducing the need for additional communication infrastructure.
Correct answer is: Utilizes existing electrical wiring
Q.4 The protocol MQTT is most suitable for which type of smart‑grid communication?
High‑speed, time‑critical protection relays
Low‑bandwidth, event‑driven telemetry
Wide‑area synchronous phasor measurement
Direct control of high‑voltage circuit breakers
Explanation - MQTT is a lightweight publish/subscribe protocol designed for low‑bandwidth, high‑latency networks, ideal for telemetry and IoT sensor data.
Correct answer is: Low‑bandwidth, event‑driven telemetry
Q.5 Which communication standard is used for Wide Area Measurement Systems (WAMS) to transmit synchrophasor data?
DNP3
IEEE C37.118
Modbus RTU
OPC UA
Explanation - IEEE C37.118 defines the format and communication methods for synchrophasor data used in WAMS.
Correct answer is: IEEE C37.118
Q.6 LoRaWAN is particularly well suited for which smart‑grid application?
High‑speed video surveillance
Real‑time protection relay coordination
Long‑range, low‑power metering data collection
In‑house Ethernet networking
Explanation - LoRaWAN offers kilometer‑scale range with very low power consumption, making it ideal for transmitting meter readings from dispersed locations.
Correct answer is: Long‑range, low‑power metering data collection
Q.7 Which layer of the OSI model does the IEC 61850 GOOSE message operate on?
Physical
Data Link
Network
Application
Explanation - GOOSE (Generic Object Oriented Substation Event) is an application‑layer protocol that provides fast, reliable messaging for protection and control.
Correct answer is: Application
Q.8 What is the typical data rate of a ZigBee communication link?
250 kbps
1 Mbps
10 Mbps
100 Mbps
Explanation - ZigBee operates at a maximum data rate of 250 kbps, which is sufficient for most sensor and meter data transmissions.
Correct answer is: 250 kbps
Q.9 Which of the following is a security concern specific to wireless smart‑grid communications?
Cable corrosion
Electromagnetic interference
Eavesdropping and spoofing
Voltage sag
Explanation - Wireless channels can be intercepted, making encryption and authentication critical to prevent unauthorized access and data manipulation.
Correct answer is: Eavesdropping and spoofing
Q.10 In the context of smart‑grid communication, what does the acronym SCADA stand for?
Supervisory Control and Data Acquisition
Smart Communication and Distributed Automation
Synchronous Control and Dynamic Analysis
Secure Control and Data Architecture
Explanation - SCADA systems monitor and control industrial processes, including power generation, transmission, and distribution.
Correct answer is: Supervisory Control and Data Acquisition
Q.11 Which of the following modulation schemes is commonly used in PLC for broadband communication?
QPSK
FSK
OFDM
BPSK
Explanation - Orthogonal Frequency Division Multiplexing (OFDM) provides robustness against multipath and noise, making it suitable for broadband PLC.
Correct answer is: OFDM
Q.12 What is the primary purpose of the DNP3 protocol in energy management systems?
High‑speed video streaming
Real‑time market price calculation
Reliable, secure telemetry and control for SCADA
Wireless sensor networking
Explanation - DNP3 (Distributed Network Protocol) is designed for robust, secure data exchange between control centers and field devices.
Correct answer is: Reliable, secure telemetry and control for SCADA
Q.13 Which of the following frequency bands is allocated for LTE‑Advanced in many countries and can be used for smart‑grid backhaul?
700 MHz
2.4 GHz
5 GHz
60 GHz
Explanation - The 700 MHz band offers good propagation characteristics and is often used for LTE‑Advanced cellular backhaul, supporting wide‑area smart‑grid communication.
Correct answer is: 700 MHz
Q.14 What does the acronym 'IEC' stand for in IEC 61850?
International Energy Council
Institute of Electrical and Electronics Engineers
International Electrotechnical Commission
Industrial Energy Consortium
Explanation - The International Electrotechnical Commission develops international standards for electrical, electronic, and related technologies.
Correct answer is: International Electrotechnical Commission
Q.15 Which type of network topology is most commonly used in smart‑meter mesh networks?
Star
Ring
Mesh
Bus
Explanation - Mesh topology allows each meter to relay data for others, providing redundancy and extended range.
Correct answer is: Mesh
Q.16 In IEC 61850, what is the purpose of the 'Sampled Values' (SV) service?
Transmit high‑frequency voltage and current samples
Send firmware updates to devices
Provide GPS time synchronization
Control circuit breaker positions
Explanation - SV transmits digitized analog measurements (e.g., voltage, current) at high rates for protection and monitoring.
Correct answer is: Transmit high‑frequency voltage and current samples
Q.17 Which communication technology uses chirp spread spectrum to achieve long‑range, low‑power transmission?
Wi‑Fi
ZigBee
LoRa
Bluetooth
Explanation - LoRa (Long Range) employs chirp spread spectrum modulation, providing robust communication over several kilometers with minimal power usage.
Correct answer is: LoRa
Q.18 What is the maximum payload size of a standard MQTT message?
128 bytes
256 KB
2 GB
4 KB
Explanation - The MQTT 3.1.1 specification defines a maximum payload of 256 KB, though implementations may impose smaller limits.
Correct answer is: 256 KB
Q.19 Which of the following is NOT a typical function of a smart‑grid communication gateway?
Protocol translation
Voltage regulation
Data aggregation
Security enforcement
Explanation - Gateways handle communication tasks such as protocol conversion and security; voltage regulation is performed by power electronic devices, not communication hardware.
Correct answer is: Voltage regulation
Q.20 In a PLC system, which noise source is most detrimental to signal integrity?
Thermal noise
Electromagnetic interference from switching devices
Cosmic background radiation
Acoustic noise
Explanation - Switching transients on power lines generate strong EMI that can corrupt PLC signals.
Correct answer is: Electromagnetic interference from switching devices
Q.21 Which of the following standards defines the communication interface for distributed energy resources (DER) in the smart grid?
IEEE 1547
IEC 61850
IEEE 802.3
ISO 9001
Explanation - IEEE 1547 provides technical specifications for interconnecting DERs with the electric power system, including communication aspects.
Correct answer is: IEEE 1547
Q.22 What is the primary benefit of using a publish/subscribe model (e.g., MQTT) over a request/response model in smart‑grid telemetry?
Higher bandwidth usage
Reduced latency for each request
Scalable distribution to multiple subscribers
Simpler device addressing
Explanation - Publish/subscribe allows a single data source to push updates to many receivers efficiently, which is ideal for widespread sensor networks.
Correct answer is: Scalable distribution to multiple subscribers
Q.23 Which communication technology operates in the unlicensed 5 GHz band and is often used for high‑throughput backhaul in smart‑grid deployments?
Wi‑MAX
ZigBee
Bluetooth
Wi‑Fi
Explanation - Wi‑Fi (IEEE 802.11ac/ax) can provide gigabit‑class data rates in the 5 GHz band, suitable for high‑capacity backhaul links.
Correct answer is: Wi‑Fi
Q.24 In IEC 61850, what does the acronym 'GOOSE' stand for?
Generic Object Oriented Substation Event
Global Operational Open System Ethernet
Grid Optimized Overhead Signal Exchange
Generalized Optical Output Signal Encoder
Explanation - GOOSE messages provide fast, reliable event communication within a substation, supporting protection and control functions.
Correct answer is: Generic Object Oriented Substation Event
Q.25 Which of the following is a key characteristic of 5G NR (New Radio) that benefits smart‑grid communications?
Fixed latency of 100 ms
Massive device connectivity with ultra‑low latency
Only supports indoor environments
Requires fiber‑optic cables
Explanation - 5G NR can handle a huge number of IoT devices and provide latencies as low as 1 ms, supporting real‑time grid control.
Correct answer is: Massive device connectivity with ultra‑low latency
Q.26 Which protocol is commonly used for time synchronization in smart‑grid devices?
NTP
SNMP
SSH
FTP
Explanation - Network Time Protocol (NTP) synchronizes clocks across devices, which is essential for accurate data timestamps and coordinated actions.
Correct answer is: NTP
Q.27 What is the main disadvantage of using Wi‑MAX for smart‑grid communication compared to fiber optics?
Higher installation cost
Limited bandwidth
Susceptibility to weather‑related attenuation
Incompatibility with IP
Explanation - Wireless links like Wi‑MAX can be degraded by rain, snow, and other atmospheric conditions, whereas fiber offers stable, high‑capacity links.
Correct answer is: Susceptibility to weather‑related attenuation
Q.28 Which of the following is a key feature of the IEC 61850-9‑2 standard?
Defines a wireless mesh protocol
Specifies sampled value transmission over Ethernet
Provides a framework for renewable energy forecasting
Mandates the use of PLC
Explanation - IEC 61850‑9‑2 (SV) defines how high‑speed sampled values are sent over Ethernet for protection and measurement.
Correct answer is: Specifies sampled value transmission over Ethernet
Q.29 In smart‑grid communication, which layer of the TCP/IP stack is responsible for routing packets between different networks?
Application
Transport
Network
Data Link
Explanation - The network layer (IP) handles addressing and routing of packets across multiple networks.
Correct answer is: Network
Q.30 Which communication technology is most appropriate for connecting a substation to a central control center over distances of 100 km or more?
ZigBee
Power Line Communication
Fiber‑optic Ethernet
Bluetooth
Explanation - Fiber offers high bandwidth, low loss, and immunity to electromagnetic interference, making it suitable for long‑distance, high‑speed links.
Correct answer is: Fiber‑optic Ethernet
Q.31 What does the acronym 'DNP3' stand for?
Distributed Network Protocol version 3
Digital Network Protection level 3
Data Network Protocol 3
Dynamic Network Performance version 3
Explanation - DNP3 is a communications protocol used between components in process automation and SCADA systems.
Correct answer is: Distributed Network Protocol version 3
Q.32 Which security mechanism is essential for protecting MQTT messages transmitted over the internet?
CRC check
TLS/SSL encryption
Parity bits
Frequency hopping
Explanation - TLS/SSL provides encryption and authentication, securing MQTT traffic against eavesdropping and tampering.
Correct answer is: TLS/SSL encryption
Q.33 What is the typical operating frequency of a standard ZigBee channel?
868 MHz
2.4 GHz
5 GHz
60 GHz
Explanation - ZigBee commonly uses the 2.4 GHz ISM band, offering 16 channels worldwide.
Correct answer is: 2.4 GHz
Q.34 Which of the following is a primary advantage of using IPv6 in smart‑grid communication networks?
Higher transmission power
Larger address space for billions of devices
Reduced latency
Built‑in encryption
Explanation - IPv6 expands the address space from 32‑bit to 128‑bit, accommodating the massive number of IoT devices in smart grids.
Correct answer is: Larger address space for billions of devices
Q.35 In a smart‑grid, which protocol is commonly used to exchange real‑time market and pricing information between utilities and consumers?
OpenADR
Modbus
BACnet
ZigBee
Explanation - Open Automated Demand Response (OpenADR) standardizes the exchange of demand‑response signals and pricing data.
Correct answer is: OpenADR
Q.36 Which communication standard is designed for high‑speed, time‑critical data exchange in substations and supports redundancy via Parallel Redundancy Protocol (PRP)?
IEC 61850
Modbus TCP
DNP3
OPC UA
Explanation - IEC 61850 incorporates PRP and HSR to provide seamless redundancy for critical substation communications.
Correct answer is: IEC 61850
Q.37 What is the main function of a Smart Meter Data Concentrator (SMDC) in the communication hierarchy?
Directly control household appliances
Aggregate meter readings and forward them to the utility
Regulate voltage at the transformer
Generate renewable energy
Explanation - SMDCs collect data from multiple smart meters, perform preprocessing, and send consolidated information to the utility's backend systems.
Correct answer is: Aggregate meter readings and forward them to the utility
Q.38 Which of the following is a key feature of the OPC UA protocol that makes it suitable for smart‑grid applications?
Stateless communication only
Built‑in security, platform independence, and data modeling
Only works with Windows OS
Requires proprietary hardware
Explanation - OPC UA offers cross‑platform interoperability, robust security, and rich information modeling, fitting modern energy management systems.
Correct answer is: Built‑in security, platform independence, and data modeling
Q.39 In a PLC system, what does the term 'notching' refer to?
A technique to avoid interference with the power frequency
A method for increasing data rate
A way to encrypt data
A type of hardware connector
Explanation - Notching removes the carrier frequency band around the mains frequency to reduce interference with power delivery.
Correct answer is: A technique to avoid interference with the power frequency
Q.40 Which of the following wireless standards provides the longest range for smart‑grid sensor networks?
Wi‑Fi (802.11ac)
Bluetooth Low Energy
ZigBee PRO
LoRaWAN
Explanation - LoRaWAN can reach several kilometers in urban areas and tens of kilometers in rural settings, surpassing the typical range of Wi‑Fi and ZigBee.
Correct answer is: LoRaWAN
Q.41 What is the typical latency requirement for protection relay communication in a substation?
Less than 1 ms
Less than 100 ms
Less than 1 s
Less than 10 s
Explanation - Protection schemes need ultra‑low latency (often sub‑millisecond) to detect and isolate faults quickly.
Correct answer is: Less than 1 ms
Q.42 Which communication technology uses line‑of‑sight microwave links to provide high‑capacity backhaul in rural smart‑grid deployments?
Power Line Communication
Free‑Space Optics (FSO)
Wi‑MAX
Cellular 4G
Explanation - FSO employs laser beams for high‑bandwidth, line‑of‑sight communication, ideal for remote backhaul where fiber is unavailable.
Correct answer is: Free‑Space Optics (FSO)
Q.43 In IEC 61850, what does the abbreviation 'MMS' stand for?
Manufacturing Messaging Service
Manufacturing Management System
Manufacturing Message Specification
Manufacturing Message Service
Explanation - MMS provides a standardized set of services for reading, writing, and monitoring data objects in power system devices.
Correct answer is: Manufacturing Message Service
Q.44 Which protocol is designed for low‑power, low‑bandwidth, event‑driven communication and is widely used in IoT devices for demand‑response signals?
CoAP
HTTP
SMTP
SNMP
Explanation - The Constrained Application Protocol (CoAP) is lightweight, runs over UDP, and is suited for constrained devices and networks.
Correct answer is: CoAP
Q.45 What is the primary function of a 'Phasor Measurement Unit' (PMU) in a smart grid?
Control transformer tap settings
Measure voltage and current phasors with precise timestamps
Provide Wi‑Fi connectivity to meters
Generate renewable power
Explanation - PMUs capture synchronized phasor data, enabling real‑time monitoring of grid stability and dynamic behavior.
Correct answer is: Measure voltage and current phasors with precise timestamps
Q.46 Which of the following is a common method to achieve network segmentation and improve security in smart‑grid communication networks?
Using a single flat IP network
Implementing VLANs
Disabling firewalls
Increasing transmission power
Explanation - Virtual LANs separate traffic logically, limiting broadcast domains and enhancing security isolation.
Correct answer is: Implementing VLANs
Q.47 What does the acronym 'HIDS' refer to in the context of smart‑grid cyber security?
Hybrid Integrated Distribution System
Host‑based Intrusion Detection System
High‑Intensity Data Service
Hydraulic Interface Development System
Explanation - HIDS monitors a single host for suspicious activities, complementing network‑based IDS for comprehensive security.
Correct answer is: Host‑based Intrusion Detection System
Q.48 Which of the following is a disadvantage of using Bluetooth Low Energy (BLE) for smart‑grid sensor networks?
Very high power consumption
Limited range (typically < 100 m)
Incompatible with IPv6
Requires fiber optic cables
Explanation - BLE's short range makes it unsuitable for wide‑area sensor deployments, though it works for close‑in applications.
Correct answer is: Limited range (typically < 100 m)
Q.49 Which standard defines the communication interface for electric vehicle (EV) charging stations in the smart grid?
IEC 61850
ISO 15118
IEEE 802.3
OPC UA
Explanation - ISO 15118 specifies the vehicle‑to‑grid communication protocol for EV charging, including authentication and power management.
Correct answer is: ISO 15118
Q.50 In a smart‑grid WAN, which technology provides the highest theoretical data rate?
4G LTE
5G NR
Wi‑MAX
Satellite communication
Explanation - 5G New Radio can achieve multi‑gigabit per second speeds, surpassing LTE, Wi‑MAX, and most satellite links.
Correct answer is: 5G NR
Q.51 What is the main purpose of the IEC 62351 series of standards?
Define mechanical dimensions of transformers
Specify cybersecurity measures for power system communications
Standardize voltage levels
Describe battery storage chemistry
Explanation - IEC 62351 provides guidelines for securing protocols like IEC 61850, DNP3, and Modbus against cyber threats.
Correct answer is: Specify cybersecurity measures for power system communications
Q.52 Which of the following best describes the term 'latency' in communication networks?
Maximum data rate achievable
Time taken for a data packet to travel from source to destination
Amount of data that can be stored in a buffer
Frequency of error correction
Explanation - Latency measures the delay between sending and receiving a packet, critical for time‑sensitive smart‑grid functions.
Correct answer is: Time taken for a data packet to travel from source to destination
Q.53 Which protocol uses a client‑server model and is widely used for remote management of industrial devices, including in smart‑grid substations?
SNMP
SMTP
FTP
IMAP
Explanation - Simple Network Management Protocol (SNMP) enables monitoring and configuration of networked devices.
Correct answer is: SNMP
Q.54 In a smart‑grid, which of the following is an example of a 'thin client' device?
A full‑featured SCADA workstation
A smart meter that only reports data
A high‑performance data historian
A renewable energy inverter with local UI
Explanation - Thin clients perform minimal processing locally and rely on a central server for heavy computation and storage.
Correct answer is: A smart meter that only reports data
Q.55 What is the primary advantage of using Time‑Sensitive Networking (TSN) in Ethernet for substation communications?
Provides wireless connectivity
Guarantees deterministic latency and low jitter
Increases the cable length limit to 10 km
Eliminates the need for routers
Explanation - TSN adds scheduling and traffic shaping mechanisms to Ethernet, making it suitable for real‑time protection and control traffic.
Correct answer is: Guarantees deterministic latency and low jitter
Q.56 Which of the following is a typical data payload transmitted by a smart meter using the DLMS/COSEM protocol?
High‑resolution video stream
Electricity consumption reading
Satellite navigation coordinates
Weather forecast data
Explanation - DLMS/COSEM is a standard for meter data exchange, focusing on consumption, voltage, current, and related measurements.
Correct answer is: Electricity consumption reading
Q.57 Which of these communication methods is most vulnerable to line‑tap attacks that can extract data from power lines?
Fiber‑optic communication
Power Line Communication (PLC)
Wireless Wi‑Fi
Satellite communication
Explanation - Since PLC signals travel over the same conductors that deliver electricity, an attacker can tap the line to intercept data.
Correct answer is: Power Line Communication (PLC)
Q.58 Which of the following is a feature of the IEC 61850 Substation Configuration Language (SCL)?
Defines physical wiring diagrams only
Specifies data models, communication settings, and device topology
Implements encryption algorithms
Provides a GUI for operator control
Explanation - SCL is an XML‑based language used to describe the configuration and topology of IEC 61850 substations.
Correct answer is: Specifies data models, communication settings, and device topology
Q.59 In the context of smart‑grid communications, what does the term 'QoS' stand for?
Quantity of Service
Quality of Service
Quick Operational Switch
Quantum Optical Signal
Explanation - QoS defines performance parameters such as bandwidth, latency, jitter, and reliability for different traffic classes.
Correct answer is: Quality of Service
Q.60 Which protocol provides a standardized way to model and exchange information about distributed energy resources (DER) in real time?
BACnet
IEC 61850
Modbus
CoAP
Explanation - IEC 61850 includes data models for DER, enabling interoperable communication of their status and control.
Correct answer is: IEC 61850
Q.61 What is the typical maximum packet size (MTU) for Ethernet frames used in IEC 61850 communications?
1500 bytes
512 bytes
64 bytes
9000 bytes
Explanation - Standard Ethernet frames have an MTU of 1500 bytes, which is commonly used for IEC 61850 messages unless jumbo frames are enabled.
Correct answer is: 1500 bytes
Q.62 Which of the following technologies is specifically designed for high‑frequency, short‑range communication between devices in a building automation system?
Z-Wave
LTE
Ethernet
Wi‑MAX
Explanation - Z‑Wave operates at low power and short range, making it suitable for home and building automation, including energy management.
Correct answer is: Z-Wave
Q.63 In a smart‑grid communication architecture, which layer typically handles encryption and authentication?
Physical
Data Link
Network
Application
Explanation - Security mechanisms such as TLS/SSL are implemented at the application layer, providing end‑to‑end protection.
Correct answer is: Application
Q.64 Which of the following is a common method to achieve time synchronization across devices in a smart‑grid network?
GPS timing receivers
Dynamic Host Configuration Protocol (DHCP)
Simple Mail Transfer Protocol (SMTP)
File Transfer Protocol (FTP)
Explanation - GPS provides precise timing signals that can be used to synchronize clocks of PMUs and other devices.
Correct answer is: GPS timing receivers
Q.65 What does the acronym 'HMI' stand for in the context of energy management systems?
High‑Memory Interface
Human‑Machine Interface
Hydraulic Monitoring Instrument
Hybrid Management Integration
Explanation - HMI refers to the user interface through which operators interact with control systems and visualize grid data.
Correct answer is: Human‑Machine Interface
Q.66 Which of the following is a benefit of using a hierarchical communication architecture (e.g., LAN → WAN → Internet) in a smart‑grid?
Eliminates the need for security
Reduces overall network latency to zero
Allows scalability and modular management of different network segments
Ensures all devices use the same IP address
Explanation - A hierarchical design separates local, regional, and wide‑area communication, making it easier to scale and manage.
Correct answer is: Allows scalability and modular management of different network segments
Q.67 Which communication protocol is most widely used for reading and writing registers in industrial devices, and is also supported by many smart‑grid components?
Modbus
SMTP
HTTPS
NTP
Explanation - Modbus (RTU/TCP) is a simple, open protocol used for device-level communication in many industrial and energy applications.
Correct answer is: Modbus
Q.68 Which of the following is a primary advantage of using IPv6 over IPv4 in smart‑grid networks?
Higher transmission power
Simpler routing tables
Support for multicast addressing and larger address space
Automatic encryption of all traffic
Explanation - IPv6 provides 128‑bit addresses and built‑in multicast, facilitating massive IoT deployments.
Correct answer is: Support for multicast addressing and larger address space
Q.69 What is the purpose of the 'heartbeat' message in many smart‑grid communication protocols?
To transmit electricity
To synchronize clocks
To indicate that a device is alive and reachable
To encrypt data
Explanation - Heartbeat messages are periodic signals used to confirm the operational status of a device.
Correct answer is: To indicate that a device is alive and reachable
Q.70 Which of the following standards defines the communication profile for distributed automation and building control, often used in energy management of commercial buildings?
BACnet
Modbus
DNP3
IEC 61850
Explanation - BACnet (Building Automation and Control network) is widely adopted for HVAC, lighting, and energy management in buildings.
Correct answer is: BACnet
Q.71 In the context of smart‑grid communications, what does the term 'backhaul' refer to?
The process of updating firmware on devices
High‑capacity links that connect local networks to the core network
The method of storing energy in batteries
A type of renewable energy source
Explanation - Backhaul links aggregate traffic from many edge devices and transport it to central data centers or control centers.
Correct answer is: High‑capacity links that connect local networks to the core network
Q.72 Which of the following communication technologies is best suited for underground cable monitoring where wireless signals cannot easily penetrate?
ZigBee
Power Line Communication
Free‑Space Optics
Bluetooth
Explanation - PLC uses the existing metallic conductors, making it ideal for underground environments where radio signals are attenuated.
Correct answer is: Power Line Communication
Q.73 Which of the following protocols is specifically designed for secure, real‑time data exchange in utility automation and supports encryption, authentication, and access control?
IEC 62351
FTP
Telnet
SMTP
Explanation - IEC 62351 adds security extensions to protocols like IEC 61850, DNP3, and Modbus, providing encryption and authentication.
Correct answer is: IEC 62351
Q.74 What is the primary function of a 'gateway' in a smart‑grid communication system?
To generate electricity
To convert and route data between different communication protocols
To physically disconnect a circuit
To store large volumes of historical data
Explanation - Gateways translate between heterogeneous protocols (e.g., ZigBee to TCP/IP), enabling interoperability.
Correct answer is: To convert and route data between different communication protocols
Q.75 Which of the following is a typical frequency band used by LTE‑Advanced for smart‑grid communication in Europe?
700 MHz
1.8 GHz
2.6 GHz
All of the above
Explanation - LTE‑Advanced can operate in multiple bands, including 700 MHz, 1.8 GHz, and 2.6 GHz, depending on spectrum allocation.
Correct answer is: All of the above
Q.76 In the context of smart‑grid communication, what does 'mesh topology' provide that a star topology does not?
Simpler cable management
Higher latency
Redundant paths for increased reliability
Reduced power consumption
Explanation - Mesh networks allow multiple routes between nodes, so if one link fails, data can be rerouted.
Correct answer is: Redundant paths for increased reliability
Q.77 Which protocol uses a binary encoding and is optimized for low‑latency, high‑frequency data transfer in substation automation?
IEC 61850 GOOSE
HTTP
SMTP
FTP
Explanation - GOOSE messages are binary, event‑driven, and designed for sub‑millisecond latency in protection schemes.
Correct answer is: IEC 61850 GOOSE
Q.78 Which of the following is an advantage of using a cloud‑based platform for smart‑grid data analytics?
Eliminates all security concerns
Provides virtually unlimited storage and compute resources
Guarantees zero network latency
Requires no internet connection
Explanation - Cloud platforms can scale resources on demand, facilitating large‑scale data analytics and machine learning.
Correct answer is: Provides virtually unlimited storage and compute resources
Q.79 In IEC 61850, what is the purpose of the 'Logical Node' (LN) concept?
To define a physical hardware component
To group related data attributes and functions logically
To encrypt communication
To provide power to devices
Explanation - Logical Nodes represent functional blocks (e.g., measurement, protection) and contain standardized data objects.
Correct answer is: To group related data attributes and functions logically
Q.80 Which of the following best describes the term 'bandwidth' in a communication link?
The physical width of a cable
Maximum data transfer rate the link can support
The amount of power transmitted
The latency of the connection
Explanation - Bandwidth is measured in bits per second and defines the capacity of a channel to carry data.
Correct answer is: Maximum data transfer rate the link can support
Q.81 What is the primary purpose of using the 'publish/subscribe' model in MQTT for smart‑grid telemetry?
To ensure point‑to‑point communication only
To enable many receivers to get updates without polling
To encrypt data automatically
To reduce the number of devices needed
Explanation - Publish/subscribe decouples producers and consumers, allowing efficient distribution of data to multiple subscribers.
Correct answer is: To enable many receivers to get updates without polling
Q.82 Which of the following is a common method for protecting smart‑grid communication networks against Denial‑of‑Service (DoS) attacks?
Increasing the transmission voltage
Implementing rate‑limiting and traffic shaping
Removing firewalls
Using only wireless links
Explanation - Rate‑limiting controls the amount of traffic a device can receive, mitigating the impact of DoS attacks.
Correct answer is: Implementing rate‑limiting and traffic shaping
Q.83 In a smart‑grid environment, which technology provides the most precise time synchronization for phasor measurement units?
Network Time Protocol (NTP)
Global Positioning System (GPS)
Simple Network Management Protocol (SNMP)
Dynamic Host Configuration Protocol (DHCP)
Explanation - GPS provides sub‑microsecond timing accuracy required for synchronized phasor measurements.
Correct answer is: Global Positioning System (GPS)
Q.84 Which of the following is a key characteristic of the IEEE 802.15.4 standard used by ZigBee and Thread?
High‑throughput video streaming
Low data rate, low power consumption, and support for mesh networking
Operates exclusively in the 5 GHz band
Requires fiber‑optic cabling
Explanation - IEEE 802.15.4 defines the physical and MAC layers for low‑rate, low‑power wireless personal area networks.
Correct answer is: Low data rate, low power consumption, and support for mesh networking
Q.85 What is the main benefit of using a 'virtual private network' (VPN) for remote access to a utility's control center?
It increases the speed of data transmission
It provides encrypted, authenticated tunnels over public networks
It eliminates the need for firewalls
It provides power backup
Explanation - VPNs secure remote connections by encrypting traffic and authenticating users, protecting sensitive grid data.
Correct answer is: It provides encrypted, authenticated tunnels over public networks
Q.86 Which of the following communication standards is designed for real‑time, high‑speed data exchange in industrial automation and is also applicable to smart‑grid substation communication?
PROFINET
HTTP/2
SMTP
FTP
Explanation - PROFINET provides deterministic Ethernet communication suitable for time‑critical industrial and substation applications.
Correct answer is: PROFINET
Q.87 Which of the following best describes the purpose of 'load shedding' commands sent over smart‑grid communication networks?
To increase the generation output
To disconnect selected loads to maintain system stability
To upgrade firmware on meters
To calibrate voltage transformers
Explanation - Load shedding reduces demand during emergencies, helping prevent frequency collapse or over‑loading.
Correct answer is: To disconnect selected loads to maintain system stability
Q.88 Which protocol is widely used for secure, web‑based remote monitoring of distributed energy resources and supports RESTful APIs?
CoAP over DTLS
HTTPS
Telnet
SNMPv1
Explanation - HTTPS provides encrypted, authenticated HTTP communication and is commonly used for web dashboards and APIs.
Correct answer is: HTTPS
Q.89 What is the typical maximum range of a standard ZigBee device operating at 2.4 GHz in an indoor environment?
10 m
30–100 m
200 m
1 km
Explanation - ZigBee can cover 30–100 m indoors depending on building materials and antenna design.
Correct answer is: 30–100 m
Q.90 Which of the following is a primary advantage of using Ethernet over serial communication (e.g., RS‑485) in modern substations?
Lower cost of cables
Higher data rates and support for IP‑based protocols
No need for power supplies
Automatic encryption
Explanation - Ethernet provides gigabit speeds and can carry IP traffic, enabling richer data and integration with IT systems.
Correct answer is: Higher data rates and support for IP‑based protocols
Q.91 In the context of smart‑grid communications, what does the term 'edge computing' refer to?
Storing all data in a central cloud
Processing data locally close to the data source to reduce latency
Using only wireless links for communication
Running the entire grid on a single server
Explanation - Edge computing performs analytics and decision‑making near sensors or meters, minimizing communication delays.
Correct answer is: Processing data locally close to the data source to reduce latency
Q.92 Which of the following is a widely used security protocol to provide authentication and confidentiality for MQTT messages?
TLS/SSL
FTP
SNMPv2c
HTTP
Explanation - TLS/SSL encrypts MQTT traffic and authenticates client and server identities.
Correct answer is: TLS/SSL
Q.93 What is the main function of a 'Phasor Data Concentrator' (PDC) in a smart‑grid communication system?
Generate electricity
Aggregate synchronized phasor measurements from multiple PMUs
Control transformer tap changers
Provide backup power to communication devices
Explanation - PDCs collect and align data from many PMUs, creating a coherent view of the grid for analysis and control.
Correct answer is: Aggregate synchronized phasor measurements from multiple PMUs
Q.94 Which of the following standards defines the communication protocol for real‑time automation in process industries and can be applied to energy management?
IEC 60870‑5‑104
IEEE 802.3
ISO 9001
Bluetooth
Explanation - IEC 60870‑5‑104 provides TCP/IP based telecontrol for SCADA and can be used in energy management.
Correct answer is: IEC 60870‑5‑104
Q.95 Which of the following communication technologies is most suitable for real‑time video surveillance in a substation?
ZigBee
LoRaWAN
Fiber‑optic Ethernet
Bluetooth Low Energy
Explanation - Fiber offers the high bandwidth needed for video streams and is immune to electromagnetic interference.
Correct answer is: Fiber‑optic Ethernet
Q.96 What is the primary role of the 'Smart Grid Interoperability Panel' (SGIP) in communication standards development?
Manufacturing smart meters
Ensuring different vendors' devices can communicate effectively
Regulating electricity prices
Building power plants
Explanation - SGIP works on defining common standards and testing procedures to achieve interoperability across the grid.
Correct answer is: Ensuring different vendors' devices can communicate effectively
Q.97 Which of the following is a key benefit of using Time‑Division Multiple Access (TDMA) in a smart‑grid wireless network?
Unlimited bandwidth
Deterministic channel access and reduced collisions
Higher transmission power
Automatic frequency hopping
Explanation - TDMA allocates distinct time slots to each device, ensuring predictable latency and minimizing interference.
Correct answer is: Deterministic channel access and reduced collisions
Q.98 In IEC 61850, which service is used to request the current value of a data attribute from a remote device?
Read (R)
Write (W)
GetDataSet
Subscribe
Explanation - The Read service retrieves the present value of a data attribute from a server.
Correct answer is: Read (R)
Q.99 Which of the following is a typical application of the 'Demand Response' (DR) signal transmitted over smart‑grid communication networks?
Increasing generation output
Temporarily reducing or shifting consumer loads during peak periods
Changing the frequency of the grid
Installing new transformers
Explanation - DR signals request consumers to lower or shift consumption, helping balance supply and demand.
Correct answer is: Temporarily reducing or shifting consumer loads during peak periods
Q.100 Which protocol provides a reliable, connection‑oriented transport service often used for critical control commands in smart‑grid networks?
UDP
TCP
ICMP
RTP
Explanation - TCP ensures ordered delivery, error checking, and retransmission, making it suitable for important control messages.
Correct answer is: TCP
Q.101 What is the typical voltage level of the communication channel used in PLC for in‑home smart‑metering?
120 V AC
230 V AC
Low‑frequency carrier (e.g., 10–100 kHz)
1 kV
Explanation - PLC for metering uses a low‑frequency carrier superimposed on the mains voltage, not the mains voltage itself.
Correct answer is: Low‑frequency carrier (e.g., 10–100 kHz)
Q.102 Which of the following is an advantage of using IPv6's built‑in multicast capability in smart‑grid sensor networks?
It reduces power consumption of devices
It allows a single packet to be delivered to multiple recipients efficiently
It guarantees zero packet loss
It eliminates the need for routers
Explanation - IPv6 multicast enables one‑to‑many communication without duplicating packets, saving bandwidth.
Correct answer is: It allows a single packet to be delivered to multiple recipients efficiently
Q.103 Which communication standard is primarily used for building automation and can be integrated with smart‑grid energy management systems?
BACnet
Modbus
DNP3
PROFINET
Explanation - BACnet is widely adopted for HVAC, lighting, and other building systems and can interface with grid management platforms.
Correct answer is: BACnet
Q.104 In a smart‑grid WAN, which technology provides the highest resilience against fiber cuts?
Microwave point‑to‑point links
Copper twisted‑pair Ethernet
Satellite communication
Power Line Communication
Explanation - Microwave links can be rapidly deployed and routed around physical fiber disruptions, offering high capacity and redundancy.
Correct answer is: Microwave point‑to‑point links
Q.105 Which of the following best describes the role of an 'aggregator' in a smart‑grid communication architecture?
A device that stores electricity
A software entity that collects and summarizes data from many devices before forwarding it upstream
A transformer that steps down voltage
A type of renewable energy source
Explanation - Aggregators reduce bandwidth usage by summarizing data (e.g., total load) before sending it to higher‑level systems.
Correct answer is: A software entity that collects and summarizes data from many devices before forwarding it upstream
Q.106 Which of the following security attacks involves an adversary sending false data to mislead grid operation?
Denial‑of‑Service (DoS)
Man‑in‑the‑Middle (MITM)
False Data Injection (FDI)
Replay attack
Explanation - FDI attacks insert fabricated measurements into the data stream, potentially causing incorrect control actions.
Correct answer is: False Data Injection (FDI)
Q.107 What is the typical packet transmission interval for a GOOSE message in a protection scheme?
Every 10 seconds
Every 1 ms to 10 ms
Every 1 minute
Every 100 ms
Explanation - GOOSE messages are sent repeatedly at millisecond intervals to ensure rapid delivery of protection events.
Correct answer is: Every 1 ms to 10 ms
Q.108 Which of the following is a primary benefit of using a 'software‑defined network' (SDN) in a smart‑grid communication system?
Higher physical layer bandwidth
Centralized control and dynamic reconfiguration of traffic flows
Elimination of all security threats
Reduced need for power generation
Explanation - SDN separates the control plane from the data plane, allowing the network to be programmed and optimized centrally.
Correct answer is: Centralized control and dynamic reconfiguration of traffic flows
Q.109 Which of the following protocols is specifically designed for high‑frequency, low‑latency data exchange in substation automation and uses MMS as its underlying service?
IEC 61850
HTTP
SMTP
FTP
Explanation - IEC 61850 leverages MMS for reliable, high‑speed communication of measurement and control data.
Correct answer is: IEC 61850
Q.110 What is the typical power consumption of a ZigBee end device in sleep mode?
10–50 mW
100–200 mW
1–2 W
5–10 W
Explanation - ZigBee devices are designed for low‑power operation, often consuming only a few tens of milliwatts in sleep mode.
Correct answer is: 10–50 mW
Q.111 Which of the following communication standards is most appropriate for integrating electric vehicle (EV) chargers with utility demand‑response programs?
OpenADR
BACnet
DNP3
IEC 61850
Explanation - OpenADR provides a standardized way for utilities to send demand‑response signals to EV chargers and other loads.
Correct answer is: OpenADR
Q.112 Which of the following best explains why Time‑Sensitive Networking (TSN) is being adopted in modern substations?
It replaces the need for any wireless communication
It enables deterministic Ethernet communication for protection and control
It provides free internet access to field devices
It allows devices to operate without any synchronization
Explanation - TSN adds timing guarantees to Ethernet, allowing it to meet the strict latency requirements of protection systems.
Correct answer is: It enables deterministic Ethernet communication for protection and control