Q.1 What does the acronym SCADA stand for in power system automation?
Supervisory Control And Data Acquisition
Systematic Control And Distributed Automation
Secure Control And Data Analysis
Smart Communication And Data Architecture
Explanation - SCADA is the standard term for Supervisory Control And Data Acquisition, a system used for remote monitoring and control of electrical grid components.
Correct answer is: Supervisory Control And Data Acquisition
Q.2 Which component of a SCADA system directly interfaces with field devices such as circuit breakers and transformers?
Human‑Machine Interface (HMI)
Remote Terminal Unit (RTU)
Master Station
Database Server
Explanation - RTUs are installed in the field and collect data from sensors, then send commands to devices like circuit breakers.
Correct answer is: Remote Terminal Unit (RTU)
Q.3 In modern SCADA architectures for smart grids, which protocol is most widely used for high‑speed, Ethernet‑based communication?
Modbus RTU
DNP3 over serial
IEC 61850
BACnet
Explanation - IEC 61850 is designed for substation automation with high‑speed Ethernet communication, making it suitable for smart grid SCADA.
Correct answer is: IEC 61850
Q.4 What is the primary role of the Human‑Machine Interface (HMI) in a SCADA system?
Store historical data
Execute control algorithms
Provide graphical display and operator control
Convert analog signals to digital
Explanation - The HMI presents real‑time data and allows operators to issue commands to the system.
Correct answer is: Provide graphical display and operator control
Q.5 Which of the following is a key advantage of using a Distributed SCADA architecture over a centralized one?
Simpler software licensing
Reduced latency and higher reliability
Lower initial capital cost
Elimination of the need for communication networks
Explanation - Distributed SCADA places processing close to devices, decreasing communication delays and improving fault tolerance.
Correct answer is: Reduced latency and higher reliability
Q.6 In SCADA terminology, what does the term 'telemetry' refer to?
The process of sending control commands to field devices
The measurement and transmission of data from remote locations
The storage of historical event logs
The encryption of communication channels
Explanation - Telemetry is the collection of measurements (voltage, current, etc.) from remote sites and sending them to the control center.
Correct answer is: The measurement and transmission of data from remote locations
Q.7 Which of the following communication media is most commonly used for RTU‑to‑master station links in wide‑area SCADA systems?
Power line carrier (PLC)
Fiber‑optic cable
Microwave radio links
Coaxial cable
Explanation - Fiber‑optic provides high bandwidth, low latency, and immunity to electromagnetic interference, making it ideal for wide‑area SCADA.
Correct answer is: Fiber‑optic cable
Q.8 Which cybersecurity measure is essential for protecting SCADA communications?
Use of unsecured Wi‑Fi for redundancy
Disabling all authentication to improve speed
Implementing encryption and digital signatures
Relying solely on firewalls at the control center
Explanation - Encryption ensures confidentiality, while digital signatures provide integrity and authentication of SCADA messages.
Correct answer is: Implementing encryption and digital signatures
Q.9 What is the typical polling interval for a SCADA system monitoring voltage levels in a distribution network?
Every 1–5 seconds
Every 30–60 seconds
Every 5–10 minutes
Every hour
Explanation - Voltage monitoring requires near‑real‑time data, so SCADA typically polls every few seconds.
Correct answer is: Every 1–5 seconds
Q.10 Which of the following best describes a PLC in the context of SCADA?
A data historian
A programmable logic controller that can execute local control logic
A graphical user interface for operators
A communication protocol
Explanation - PLCs are rugged computers used in the field to run control programs, often integrated with SCADA for local automation.
Correct answer is: A programmable logic controller that can execute local control logic
Q.11 In IEC 61850, what does the term 'GOOSE' stand for?
Generic Object Oriented Substation Event
Global Operational Overlay for Energy
Grid Optimized Open System Exchange
Generalized Object Oriented Security Engine
Explanation - GOOSE messages are used for fast, reliable transmission of status changes in IEC 61850‑based substations.
Correct answer is: Generic Object Oriented Substation Event
Q.12 Which component in a SCADA system is primarily responsible for archiving time‑stamped data for later analysis?
Historian
RTU
HMI
Gateway
Explanation - A historian collects and stores large volumes of time‑series data for trend analysis and reporting.
Correct answer is: Historian
Q.13 What is the main purpose of an alarm in a SCADA system?
To notify operators of abnormal or fault conditions
To increase data sampling rate
To synchronize clocks across devices
To backup configuration files
Explanation - Alarms draw operator attention to events that require immediate action or investigation.
Correct answer is: To notify operators of abnormal or fault conditions
Q.14 Which of the following is NOT a typical function of a SCADA master station?
Data acquisition from RTUs
Execution of control commands
Direct physical switching of breakers
Historical data storage
Explanation - Physical switching is done by field devices; the master station issues commands but does not physically switch.
Correct answer is: Direct physical switching of breakers
Q.15 In a SCADA system, what is a 'redundant communication path' used for?
To increase data throughput
To provide a backup channel in case the primary link fails
To encrypt data
To reduce the number of RTUs required
Explanation - Redundancy ensures continuous operation despite failures in a communication link.
Correct answer is: To provide a backup channel in case the primary link fails
Q.16 Which protocol is commonly used for SCADA communication over TCP/IP in utility networks?
Modbus TCP
Profibus DP
CANopen
ZigBee
Explanation - Modbus TCP adapts the classic Modbus protocol to run over Ethernet/TCP‑IP, widely used in utility SCADA.
Correct answer is: Modbus TCP
Q.17 What does the term 'state estimation' refer to in the context of SCADA for smart grids?
Predicting future electricity prices
Calculating the most probable set of voltage magnitudes and angles based on measurements
Estimating the age of field devices
Measuring the physical size of transformers
Explanation - State estimation uses SCADA measurements to derive a consistent view of the grid's electrical state.
Correct answer is: Calculating the most probable set of voltage magnitudes and angles based on measurements
Q.18 Which of the following best describes 'wide‑area measurement system (WAMS)' integration with SCADA?
WAMS replaces SCADA completely
WAMS provides high‑speed phasor data that enhances SCADA’s situational awareness
WAMS only monitors water distribution networks
WAMS is a type of HMI
Explanation - WAMS, using PMUs, feeds synchrophasor data to SCADA, improving real‑time monitoring of the grid.
Correct answer is: WAMS provides high‑speed phasor data that enhances SCADA’s situational awareness
Q.19 What is a typical security vulnerability of using Modbus RTU in a SCADA environment?
Built‑in encryption makes it too slow
Lack of authentication allows spoofing of commands
It only works over fiber optics
It requires high‑level programming knowledge
Explanation - Modbus RTU does not provide authentication or encryption, making it susceptible to malicious command injection.
Correct answer is: Lack of authentication allows spoofing of commands
Q.20 Which feature of IEC 61850 allows multiple devices to share the same configuration data?
SCL (Substation Configuration Language)
GOOSE
MMS (Manufacturing Message Specification)
SV (Sampled Values)
Explanation - SCL is an XML‑based language used to describe and exchange substation configuration among devices.
Correct answer is: SCL (Substation Configuration Language)
Q.21 In the context of SCADA, what does the term 'latency' refer to?
The amount of data stored in the historian
The delay between measurement acquisition and its appearance on the HMI
The number of alarms generated per hour
The speed of the processor in the RTU
Explanation - Latency is the time lag from when data is sensed to when it is displayed or used for control.
Correct answer is: The delay between measurement acquisition and its appearance on the HMI
Q.22 Which of the following is a primary benefit of using a 'virtualized' SCADA environment?
Eliminates the need for physical RTUs
Reduces hardware costs and enables rapid testing of new functions
Provides unlimited bandwidth
Guarantees zero latency
Explanation - Virtualization allows SCADA components to run on common servers, lowering cost and simplifying updates.
Correct answer is: Reduces hardware costs and enables rapid testing of new functions
Q.23 What is the main purpose of a 'gateway' in a SCADA system architecture?
To store historical data
To convert protocols between legacy field devices and modern network layers
To generate user manuals
To power field devices
Explanation - Gateways translate between different communication protocols, enabling integration of older equipment.
Correct answer is: To convert protocols between legacy field devices and modern network layers
Q.24 Which of the following SCADA data types typically requires the highest sampling rate?
Temperature of transformer oil
Breaker status (open/close)
Voltage phasors from PMUs
Daily energy consumption
Explanation - Phasor Measurement Units (PMUs) provide high‑frequency voltage/current phasor data (30–60 samples per second).
Correct answer is: Voltage phasors from PMUs
Q.25 Which method is commonly used to synchronize clocks across SCADA devices?
Network Time Protocol (NTP)
Domain Name System (DNS)
Simple Mail Transfer Protocol (SMTP)
File Transfer Protocol (FTP)
Explanation - NTP provides time synchronization, essential for accurate timestamping of SCADA measurements.
Correct answer is: Network Time Protocol (NTP)
Q.26 In a SCADA system, what does the term 'dead‑band' refer to?
A range of values where no control action is taken to avoid unnecessary switching
The physical distance between an RTU and a sensor
The maximum data rate of a communication link
A type of encryption algorithm
Explanation - Dead‑band prevents frequent toggling of control devices when measurements fluctuate within a small range.
Correct answer is: A range of values where no control action is taken to avoid unnecessary switching
Q.27 Which of the following statements about DNP3 is correct?
It only works over wireless networks
It includes built‑in security features such as authentication and encryption in the DNP3 Secure Authentication extension
It cannot be used for control commands, only for telemetry
It is a proprietary protocol owned by a single vendor
Explanation - The DNP3 Secure Authentication extension adds cryptographic security to the otherwise insecure base protocol.
Correct answer is: It includes built‑in security features such as authentication and encryption in the DNP3 Secure Authentication extension
Q.28 What is the role of a 'soft‑real‑time' operating system in a SCADA server?
Guarantee absolute timing deadlines for all tasks
Provide deterministic response times sufficient for SCADA without the cost of hard‑real‑time systems
Run only on mobile devices
Replace the need for RTUs
Explanation - Soft‑real‑time OSes give predictable performance suitable for SCADA control loops, which are less stringent than hard real‑time requirements.
Correct answer is: Provide deterministic response times sufficient for SCADA without the cost of hard‑real‑time systems
Q.29 Which of the following is a common cause of 'communication jitter' in SCADA networks?
Consistent packet size
Variable network traffic leading to unpredictable delays
Use of fiber‑optic cables
Static IP addressing
Explanation - Jitter occurs when packet arrival times vary due to fluctuating traffic loads or queuing.
Correct answer is: Variable network traffic leading to unpredictable delays
Q.30 When designing a SCADA system for a renewable‑energy farm, which additional data source is often integrated?
Weather forecast and turbine blade pitch information
Traffic congestion reports
Satellite imagery of the region
Stock market indices
Explanation - Renewable farms require weather data and turbine operating parameters to optimize generation and grid integration.
Correct answer is: Weather forecast and turbine blade pitch information
Q.31 What does 'MMS' stand for in IEC 61850 communications?
Manufacturing Message Specification
Massive Messaging Service
Modbus Management System
Metering Monitoring Suite
Explanation - MMS is the protocol used for client‑server communications in IEC 61850, handling configuration, control, and data exchange.
Correct answer is: Manufacturing Message Specification
Q.32 Which of the following is NOT a typical reason for implementing SCADA redundancy at the master station level?
Improved fault tolerance
Load balancing of operator workstations
Ensuring continuous operation during hardware failure
Eliminating the need for backup power
Explanation - Redundancy addresses hardware/software failures, but backup power (UPS) is still required to protect against outages.
Correct answer is: Eliminating the need for backup power
Q.33 In the context of SCADA data storage, what is the main difference between a 'historian' and a traditional relational database?
Historian is optimized for high‑speed time‑series data ingestion and retrieval
Relational databases cannot store numeric data
Historian only stores alarm data
Relational databases are always cloud‑based
Explanation - Historians are purpose‑built to handle large volumes of time‑stamped measurements efficiently.
Correct answer is: Historian is optimized for high‑speed time‑series data ingestion and retrieval
Q.34 Which of the following best describes 'event‑driven' data acquisition in SCADA?
Polling devices at fixed intervals
Sending data only when a change exceeds a predefined threshold
Storing all data in local memory
Using satellite links for communication
Explanation - Event‑driven acquisition reduces bandwidth by transmitting data only on significant changes.
Correct answer is: Sending data only when a change exceeds a predefined threshold
Q.35 What is the primary purpose of a 'digital twin' in modern SCADA implementations?
To create a physical replica of the substation
To run a real‑time simulation of the grid for testing and predictive analysis
To replace all field sensors
To provide a backup power source
Explanation - Digital twins mirror the physical system, enabling operators to test scenarios and predict outcomes without affecting the real grid.
Correct answer is: To run a real‑time simulation of the grid for testing and predictive analysis
Q.36 Which layer of the OSI model does the Modbus TCP protocol operate on?
Physical layer
Data Link layer
Transport layer
Application layer
Explanation - Modbus TCP is an application‑layer protocol that runs over TCP/IP (Transport layer).
Correct answer is: Application layer
Q.37 In a SCADA system, what is the function of a 'watchdog timer' within an RTU?
To synchronize the RTU clock with GPS
To detect software hangs and trigger a restart
To encrypt outgoing data
To measure power factor
Explanation - Watchdog timers monitor system health; if the software fails to reset the timer, the RTU reboots.
Correct answer is: To detect software hangs and trigger a restart
Q.38 Which SCADA feature helps prevent 'command injection' attacks on field devices?
Using static IP addresses
Implementing role‑based access control and command whitelisting
Increasing the polling rate
Disabling all alarms
Explanation - Restricting which commands can be sent and who can send them mitigates unauthorized control attempts.
Correct answer is: Implementing role‑based access control and command whitelisting
Q.39 Which of the following is an example of a 'soft‑sensor' in SCADA?
A physical temperature probe
A calculated estimate of line load based on voltage and current measurements
A protective relay
A battery backup unit
Explanation - Soft‑sensors derive values using algorithms from existing measurements rather than direct physical sensors.
Correct answer is: A calculated estimate of line load based on voltage and current measurements
Q.40 What is the main advantage of using IPv6 over IPv4 in SCADA networks?
Higher data encryption standards
Larger address space allowing unique addressing of many field devices
Faster transmission speeds
Compatibility with legacy Modbus devices
Explanation - IPv6 provides a vastly larger address pool, facilitating unique IPs for a massive number of SCADA nodes.
Correct answer is: Larger address space allowing unique addressing of many field devices
Q.41 Which term describes the process of converting analog sensor signals to digital format for SCADA processing?
Modulation
Demultiplexing
Analog‑to‑Digital Conversion (ADC)
Signal attenuation
Explanation - ADC circuits sample analog voltages/currents and produce digital values usable by SCADA software.
Correct answer is: Analog‑to‑Digital Conversion (ADC)
Q.42 In SCADA, what does the acronym 'HIS' stand for?
Human Interface System
Historical Information Store
High‑Integrity Switch
Hybrid Integrated Sensor
Explanation - HIS refers to the component that archives past measurements for analysis and reporting.
Correct answer is: Historical Information Store
Q.43 Which of the following best describes the concept of 'load shedding' in SCADA‑controlled grids?
Increasing generation output
Intentionally disconnecting non‑critical loads to preserve system stability
Installing larger transformers
Upgrading communication cables
Explanation - Load shedding is an emergency control action to prevent system collapse during overloads.
Correct answer is: Intentionally disconnecting non‑critical loads to preserve system stability
Q.44 What is the typical data rate of a GOOSE message in IEC 61850?
Below 1 kbps
Approximately 10–30 kbps
Around 1 Mbps
Over 10 Mbps
Explanation - GOOSE messages are small, high‑priority status messages that usually occupy low bandwidth (10‑30 kbps).
Correct answer is: Approximately 10–30 kbps
Q.45 Which type of SCADA architecture is most suitable for a geographically dispersed utility with many remote substations?
Standalone SCADA
Hierarchical (multi‑level) SCADA
Peer‑to‑peer SCADA
Centralized monolithic SCADA
Explanation - A hierarchical architecture uses regional control centers that aggregate data before sending it to a central master, fitting large, dispersed networks.
Correct answer is: Hierarchical (multi‑level) SCADA
Q.46 Which of the following is a primary function of a 'protective relay' when integrated with SCADA?
To archive historical data
To provide fast tripping of circuit breakers based on abnormal conditions
To display data on the HMI
To generate power forecasts
Explanation - Protective relays monitor parameters and issue immediate trip commands, often coordinated with SCADA for supervision.
Correct answer is: To provide fast tripping of circuit breakers based on abnormal conditions
Q.47 What does 'IEC 60870‑5‑104' specify in SCADA communication?
A wireless protocol for home automation
A TCP/IP based protocol for telecontrol over wide area networks
A protocol for smart meters only
A data compression algorithm
Explanation - IEC 60870‑5‑104 is the network‑layer version of IEC 60870‑5, enabling telecontrol over IP networks.
Correct answer is: A TCP/IP based protocol for telecontrol over wide area networks
Q.48 Which of the following best characterizes a 'soft‑SCADA' system?
A system that runs entirely on mobile phones
A SCADA implementation using commercial‑off‑the‑shelf (COTS) hardware and software components
A SCADA that does not require any communication network
A SCADA that only monitors water distribution
Explanation - Soft‑SCADA leverages standard PCs, servers, and software, reducing cost and development time.
Correct answer is: A SCADA implementation using commercial‑off‑the‑shelf (COTS) hardware and software components
Q.49 What is the purpose of a 'digital certificate' in SCADA security?
To increase the speed of data transmission
To verify the identity of communicating devices and enable encrypted sessions
To store historical power flow data
To control the voltage level of transformers
Explanation - Digital certificates provide authentication and support TLS/SSL encryption for secure SCADA communications.
Correct answer is: To verify the identity of communicating devices and enable encrypted sessions
Q.50 Which of the following is a typical characteristic of a 'real‑time' SCADA alarm?
It is generated only after a daily batch process
It is triggered immediately when a predefined threshold is crossed
It is logged only at the end of the month
It requires manual verification before display
Explanation - Real‑time alarms alert operators instantly upon detection of abnormal conditions.
Correct answer is: It is triggered immediately when a predefined threshold is crossed
Q.51 Which of the following best explains the concept of 'state estimation convergence'?
The algorithm reaches a solution that satisfies measurement residuals within acceptable limits
The SCADA system powers on automatically
All RTUs are synchronized to the same clock
The HMI refreshes its screen every second
Explanation - Convergence means the iterative state estimation process has found a stable solution consistent with the measurements.
Correct answer is: The algorithm reaches a solution that satisfies measurement residuals within acceptable limits
Q.52 Which of the following is an example of a 'firmware' upgrade in a SCADA RTU?
Replacing the RTU hardware chassis
Updating the operating system of the HMI workstation
Loading a new version of the device's embedded control software
Adding more disk storage to the historian
Explanation - Firmware upgrades modify the low‑level code that runs on RTU microcontrollers.
Correct answer is: Loading a new version of the device's embedded control software
Q.53 What is the primary purpose of 'sampled values' (SV) in IEC 61850?
To transmit analog measurement data (e.g., voltage, current) over Ethernet with precise time stamps
To encrypt SCADA traffic
To store configuration files
To generate alarm notifications
Explanation - SV messages carry high‑speed sampled analog values for protection and control functions.
Correct answer is: To transmit analog measurement data (e.g., voltage, current) over Ethernet with precise time stamps
Q.54 Which of the following best describes the function of a 'communication protocol translator' in a SCADA gateway?
It compresses data to reduce bandwidth usage
It converts messages from one protocol (e.g., DNP3) to another (e.g., IEC 61850)
It generates power forecasts
It powers field devices remotely
Explanation - Protocol translators allow heterogeneous devices to interoperate within a unified SCADA system.
Correct answer is: It converts messages from one protocol (e.g., DNP3) to another (e.g., IEC 61850)
Q.55 Which factor most directly influences the maximum number of RTUs that can be supported by a SCADA master station?
The color of the HMI screens
The processing power and memory of the master server
The geographic location of the utility
The brand of RTU hardware
Explanation - The master station's hardware determines how many concurrent connections and data streams it can handle.
Correct answer is: The processing power and memory of the master server
Q.56 In a SCADA system, what is a 'heartbeat' signal used for?
To synchronize voltage levels across the grid
To periodically verify that a remote device is still online and responsive
To encrypt communication
To measure ambient temperature
Explanation - Heartbeats are simple periodic messages that confirm the health of a communication link.
Correct answer is: To periodically verify that a remote device is still online and responsive
Q.57 Which of the following is a common method for detecting false data injection attacks in SCADA?
Increasing the polling interval
Implementing statistical anomaly detection on measurement streams
Disabling all alarms
Using only analog sensors
Explanation - Anomaly detection algorithms can identify data that deviates from expected physical laws, indicating possible attacks.
Correct answer is: Implementing statistical anomaly detection on measurement streams
Q.58 What does the term 'IEC 60870‑5‑101' refer to?
A wireless protocol for home automation
A serial communication protocol for telecontrol over point‑to‑point links
A data compression algorithm
A type of protective relay
Explanation - IEC 60870‑5‑101 defines a serial (often RS‑485) telecontrol protocol used in SCADA.
Correct answer is: A serial communication protocol for telecontrol over point‑to‑point links
Q.59 Which of the following best explains why a SCADA system might use 'time‑synchronized' measurements?
To reduce the size of the data files
To enable accurate correlation of data from geographically dispersed devices
To avoid the need for encryption
To increase the voltage level of the grid
Explanation - Time stamps (often from GPS) allow operators to align measurements from different locations for coherent analysis.
Correct answer is: To enable accurate correlation of data from geographically dispersed devices
Q.60 In a SCADA network, which device typically performs the function of 'protocol conversion' between Modbus RTU and Modbus TCP?
HMI workstation
RTU
Protocol gateway (or converter)
Circuit breaker
Explanation - A gateway translates serial Modbus RTU frames to Modbus TCP packets for Ethernet networks.
Correct answer is: Protocol gateway (or converter)
Q.61 Which of the following is a key benefit of using 'edge computing' in SCADA for smart grids?
Eliminating the need for a central control center
Processing data locally to reduce latency and bandwidth usage
Increasing the size of the historian database
Providing free Wi‑Fi to consumers
Explanation - Edge computing performs analytics at the device or substation level, improving response times and reducing data traffic.
Correct answer is: Processing data locally to reduce latency and bandwidth usage
Q.62 Which SCADA component typically runs the 'OPC UA' server for data interoperability?
RTU
HMI
Gateway or middleware server
Circuit breaker
Explanation - OPC UA servers are often hosted on middleware/gateway platforms to expose data to various applications.
Correct answer is: Gateway or middleware server
Q.63 What is the purpose of a 'fail‑safe' design in SCADA-controlled actuators?
To ensure that, in the event of a failure, the actuator moves to a safe position (e.g., open breaker)
To increase data sampling rates
To encrypt communication
To reduce the need for human operators
Explanation - Fail‑safe mechanisms protect the system by defaulting to a safe state if control is lost.
Correct answer is: To ensure that, in the event of a failure, the actuator moves to a safe position (e.g., open breaker)
Q.64 Which of the following best describes the concept of 'load forecasting' integration with SCADA?
Using historical data to predict future demand and adjust control set‑points in advance
Measuring the temperature of transformers only
Replacing all RTUs with smart meters
Running the SCADA system on solar power
Explanation - Load forecasting helps operators plan generation and grid operations, and the forecasts can be fed into SCADA for automated adjustments.
Correct answer is: Using historical data to predict future demand and adjust control set‑points in advance
Q.65 Which of the following statements about 'SCADA cyber‑physical attacks' is correct?
They only affect the physical equipment, not the software
They target both the information technology (IT) and operational technology (OT) layers to disrupt grid operation
They can be completely prevented by using firewalls alone
They are unrelated to data integrity
Explanation - Cyber‑physical attacks exploit vulnerabilities in both IT (network, servers) and OT (RTUs, PLCs) to cause physical impact.
Correct answer is: They target both the information technology (IT) and operational technology (OT) layers to disrupt grid operation
Q.66 In IEC 61850, what is the purpose of the 'Logical Node' concept?
To define a physical hardware component like a breaker
To group related data objects and functions (e.g., measurement, control) for a device
To encrypt communication between devices
To store historical alarm logs
Explanation - Logical Nodes encapsulate specific functions (e.g., XCBR for circuit breaker) and associated data models.
Correct answer is: To group related data objects and functions (e.g., measurement, control) for a device
Q.67 Which of the following is a typical reason for employing 'dual‑redundant' PLCs in a SCADA-controlled substation?
To double the power output of the substation
To provide hot‑standby capability, ensuring continuous operation if one PLC fails
To increase the number of alarms
To allow the use of older communication protocols
Explanation - Dual‑redundant PLCs run in parallel; if the primary fails, the secondary takes over instantly.
Correct answer is: To provide hot‑standby capability, ensuring continuous operation if one PLC fails
Q.68 What does the term 'SCADA latency budget' refer to?
The total allowable delay from measurement to control action for safe operation
The amount of storage space allocated to the historian
The maximum number of devices that can be connected
The power consumption limit of field devices
Explanation - Latency budget defines the maximum permissible delay to meet stability and protection requirements.
Correct answer is: The total allowable delay from measurement to control action for safe operation
Q.69 Which of the following best describes a 'soft‑real‑time' SCADA control loop?
A loop that must meet strict millisecond‑level deadlines
A loop where occasional deadline misses are acceptable without causing system instability
A loop that never uses timers
A loop that runs only during maintenance windows
Explanation - Soft‑real‑time systems tolerate minor timing variations, unlike hard real‑time systems that cannot miss deadlines.
Correct answer is: A loop where occasional deadline misses are acceptable without causing system instability
Q.70 Which of the following is NOT a typical SCADA data visualization technique?
Time‑series trend plots
Geospatial (GIS) mapping of assets
3‑D virtual reality simulation of the grid
ASCII‑only text logs
Explanation - While text logs exist, they are not considered a primary visualization technique like graphs, maps, or 3‑D models.
Correct answer is: ASCII‑only text logs
Q.71 What is the main advantage of using 'IEC 62351' in a SCADA environment?
It defines a set of security standards for power system communications
It increases the voltage rating of transformers
It provides a new type of sensor for temperature
It replaces all legacy protocols
Explanation - IEC 62351 provides guidelines for authentication, encryption, and key management in power system protocols.
Correct answer is: It defines a set of security standards for power system communications
Q.72 In a SCADA system, what is the function of a 'filter' applied to incoming measurement data?
To block unauthorized users
To remove noise and smooth the data before analysis
To convert analog signals to digital
To increase the sampling rate
Explanation - Filters (e.g., low‑pass) clean measurement data, improving the reliability of control decisions.
Correct answer is: To remove noise and smooth the data before analysis
Q.73 Which of the following best explains the concept of 'SCADA interoperability'?
All devices must be from the same manufacturer
The ability of different vendors' hardware and software to exchange data seamlessly using standard protocols
Using only proprietary protocols
Running SCADA on a single computer
Explanation - Interoperability is achieved through open standards like IEC 61850, Modbus, DNP3, etc.
Correct answer is: The ability of different vendors' hardware and software to exchange data seamlessly using standard protocols
Q.74 Which of the following is a common method for achieving time synchronization across SCADA devices in a wide area network?
Using GPS receivers at each device
Manually setting the clocks once per year
Relying on the local power frequency
Adjusting clocks based on temperature
Explanation - GPS provides accurate UTC time to synchronize clocks across dispersed SCADA components.
Correct answer is: Using GPS receivers at each device
Q.75 In the context of SCADA, what does the term 'alarm priority' refer to?
The order in which alarms are displayed based on their severity and impact
The speed of the communication link
The size of the data packet
The type of sensor used
Explanation - Priority helps operators focus on the most critical issues first.
Correct answer is: The order in which alarms are displayed based on their severity and impact
Q.76 Which of the following is a typical feature of a 'SCADA historian' that differentiates it from a generic relational database?
Support for high‑frequency time‑series inserts and fast range queries
Ability to run on smartphones
Built‑in video streaming capabilities
Automatic generation of 3‑D grid models
Explanation - Historians are optimized for rapid storage and retrieval of massive time‑stamped datasets.
Correct answer is: Support for high‑frequency time‑series inserts and fast range queries
Q.77 Which of the following is a key advantage of using 'cloud‑based SCADA' services?
Zero latency communication
Scalable computing resources and reduced on‑premises hardware costs
Elimination of all cybersecurity concerns
Ability to operate without any internet connection
Explanation - Cloud platforms allow utilities to scale resources as needed and lower capital expenditures, though they introduce new security considerations.
Correct answer is: Scalable computing resources and reduced on‑premises hardware costs
Q.78 In a SCADA system, which device typically hosts the 'OPC Data Access (DA)' server for real‑time data exchange?
RTU
HMI workstation
SCADA master server or middleware
Circuit breaker
Explanation - OPC DA servers are usually installed on central servers to provide standardized real‑time data access to clients.
Correct answer is: SCADA master server or middleware
Q.79 Which of the following best explains why 'redundant power supplies' are used in critical SCADA equipment?
To double the processing speed
To ensure continuous operation during a power failure of one supply
To increase the number of alarms
To allow the device to operate at higher voltages
Explanation - Redundant (dual) power supplies provide fault tolerance, keeping equipment running if one source fails.
Correct answer is: To ensure continuous operation during a power failure of one supply
Q.80 Which communication protocol is specifically designed for high‑speed, low‑latency transmission of sampled voltage and current values?
IEC 61850 Sampled Values (SV)
Modbus RTU
BACnet
Profibus DP
Explanation - SV messages carry high‑frequency phasor data for protection and control, using IEC 61850.
Correct answer is: IEC 61850 Sampled Values (SV)
Q.81 What does the acronym 'RTU' stand for?
Remote Transmission Unit
Remote Terminal Unit
Real‑Time Utility
Redundant Transfer Utility
Explanation - RTU is the field device that gathers data from sensors and sends commands to actuators.
Correct answer is: Remote Terminal Unit
Q.82 Which of the following is a common cause of 'communication packet loss' in a SCADA network?
Using fiber‑optic cables
Excessive network congestion or buffer overflows
Implementing encryption
Having redundant power supplies
Explanation - High traffic can exceed the capacity of switches/routers, causing packets to be dropped.
Correct answer is: Excessive network congestion or buffer overflows
Q.83 Which of the following best describes the purpose of a 'SCADA test‑bed'?
A live power plant used for commercial operation
A controlled environment where new SCADA functions, protocols, and security measures can be evaluated without affecting the real grid
A storage room for spare RTUs
A software that automatically writes reports
Explanation - Test‑beds allow safe experimentation and validation before deployment.
Correct answer is: A controlled environment where new SCADA functions, protocols, and security measures can be evaluated without affecting the real grid
Q.84 In IEC 61850, what does the abbreviation 'MMS' stand for?
Manufacturing Message Specification
Multi‑Media System
Modbus Monitoring Service
Metering Management Suite
Explanation - MMS is the protocol used for client‑server communications in IEC 61850 based systems.
Correct answer is: Manufacturing Message Specification
Q.85 Which of the following is an example of a 'distributed' SCADA architecture?
All RTUs connect directly to a single central master server located in the control center
Each regional control center hosts its own master server, which then synchronizes with a central server
A single workstation running both HMI and historian
A system with no network connections
Explanation - Distributed SCADA spreads processing and data collection across multiple sites for scalability and resilience.
Correct answer is: Each regional control center hosts its own master server, which then synchronizes with a central server
Q.86 Which of the following is a typical function of a 'SCADA alarm acknowledgement' procedure?
It clears the alarm from the system and records which operator responded
It increases the voltage of the affected line
It automatically repairs the faulty equipment
It disables all communications for 5 minutes
Explanation - Acknowledgement logs who has seen the alarm and prevents repeated alerts for the same event.
Correct answer is: It clears the alarm from the system and records which operator responded
Q.87 What is the primary role of a 'SCADA security zone' in a utility network?
To separate critical control traffic from corporate IT traffic using firewalls and demilitarized zones (DMZ)
To increase the voltage rating of substations
To store historical data longer
To provide extra lighting in the control room
Explanation - Security zones isolate the SCADA network, reducing exposure to external threats.
Correct answer is: To separate critical control traffic from corporate IT traffic using firewalls and demilitarized zones (DMZ)
Q.88 Which of the following best describes 'time‑synchronized phasor measurement' in the context of SCADA?
Measuring voltage angles without a time reference
Collecting voltage and current phasors that are tagged with a common timestamp (e.g., GPS), allowing direct comparison across locations
Recording temperature data at regular intervals
Measuring only the magnitude of voltage
Explanation - Synchronized phasors enable accurate real‑time state estimation and fault location.
Correct answer is: Collecting voltage and current phasors that are tagged with a common timestamp (e.g., GPS), allowing direct comparison across locations
Q.89 Which of the following is a common way to improve SCADA system reliability in harsh environmental conditions?
Using outdoor‑rated enclosures with proper IP protection for RTUs and PLCs
Running all devices at maximum voltage
Disabling all alarms
Operating without any grounding
Explanation - Rugged, weather‑sealed hardware protects against dust, moisture, and temperature extremes.
Correct answer is: Using outdoor‑rated enclosures with proper IP protection for RTUs and PLCs
Q.90 Which protocol extension adds authentication and encryption to the classic DNP3 protocol?
DNP3 Secure Authentication (SA)
DNP3 Plus
DNP3 Advanced
DNP3 Crypto
Explanation - The SA extension provides cryptographic security to DNP3 communications.
Correct answer is: DNP3 Secure Authentication (SA)
Q.91 In SCADA, what is the purpose of a 'dead‑band' in a control loop for voltage regulation?
To prevent continuous toggling of the regulator when voltage stays within a small acceptable range
To increase the sampling rate
To encrypt the control signal
To store historical voltage data
Explanation - Dead‑band creates a tolerance band that avoids unnecessary actuator operations.
Correct answer is: To prevent continuous toggling of the regulator when voltage stays within a small acceptable range
Q.92 Which of the following best defines the term 'SCADA data historian compression'?
Reducing the size of stored time‑series data using algorithms like delta encoding or run‑length encoding
Increasing the voltage level of the grid
Compressing the physical size of RTU hardware
Limiting the number of alarms generated
Explanation - Compression techniques reduce storage requirements while preserving essential data fidelity.
Correct answer is: Reducing the size of stored time‑series data using algorithms like delta encoding or run‑length encoding
Q.93 Which of the following is an example of a 'soft‑failover' strategy in SCADA communications?
Switching to a backup communication path only after detecting loss of the primary link
Turning off all RTUs during maintenance
Increasing the voltage on all lines
Disabling the HMI during a storm
Explanation - Soft‑failover monitors link health and switches to redundant paths without interrupting operation.
Correct answer is: Switching to a backup communication path only after detecting loss of the primary link
Q.94 Which of the following statements about 'SCADA network segmentation' is true?
It merges all traffic into a single broadcast domain
It isolates critical SCADA traffic from less critical traffic to improve security and performance
It eliminates the need for firewalls
It requires all devices to use the same IP address
Explanation - Segmentation uses VLANs, firewalls, and DMZs to separate traffic, limiting exposure and congestion.
Correct answer is: It isolates critical SCADA traffic from less critical traffic to improve security and performance
Q.95 What is the typical function of a 'SCADA command queue' in the master server?
To store measurement data temporarily
To hold operator‑issued control commands until they can be safely transmitted to field devices
To archive alarm logs
To manage user passwords
Explanation - The command queue ensures ordered, reliable delivery of control actions.
Correct answer is: To hold operator‑issued control commands until they can be safely transmitted to field devices
Q.96 Which of the following best describes the concept of 'SCADA event correlation'?
Linking multiple related alarms and measurements to identify a single underlying cause
Increasing the number of alarms displayed
Synchronizing clocks between devices
Compressing data before storage
Explanation - Event correlation reduces alarm flooding and helps operators focus on root causes.
Correct answer is: Linking multiple related alarms and measurements to identify a single underlying cause
Q.97 In a SCADA system, which component typically performs 'protocol encapsulation' for transmitting Modbus data over a cellular network?
RTU
Cellular modem with an embedded gateway
HMI workstation
Circuit breaker
Explanation - The modem/gateway wraps Modbus frames inside IP packets suitable for cellular transmission.
Correct answer is: Cellular modem with an embedded gateway
Q.98 Which of the following is a major reason for implementing 'SCADA system hardening'?
To increase the system's processing speed
To reduce the number of required field devices
To minimize the attack surface by disabling unnecessary services and applying security patches
To allow the system to run on battery power only
Explanation - Hardening improves resilience against cyber attacks by removing or securing vulnerable components.
Correct answer is: To minimize the attack surface by disabling unnecessary services and applying security patches
Q.99 Which of the following is a typical characteristic of a 'high‑availability' SCADA master server configuration?
Active‑passive clustering with automatic failover
Single point of failure design
Running on a laptop in the control room
No backup power supply
Explanation - Active‑passive (or active‑active) clustering ensures the system stays online if one server fails.
Correct answer is: Active‑passive clustering with automatic failover
Q.100 What is the purpose of the 'GOOSE' protocol in IEC 61850‑based SCADA systems?
To transmit high‑frequency sampled analog values
To send fast, reliable status and event messages between IEDs
To provide DNS services for the network
To encrypt all communications
Explanation - GOOSE (Generic Object Oriented Substation Event) enables rapid dissemination of critical events.
Correct answer is: To send fast, reliable status and event messages between IEDs
Q.101 Which of the following best explains why 'SCADA data timestamping' is critical for fault analysis?
It allows operators to know exactly when each measurement was taken, enabling precise sequencing of events during a fault
It reduces the size of data packets
It eliminates the need for backups
It increases the voltage of the grid
Explanation - Accurate timestamps are essential for reconstructing the chronology of events in post‑fault analysis.
Correct answer is: It allows operators to know exactly when each measurement was taken, enabling precise sequencing of events during a fault
Q.102 Which of the following is NOT a standard method for securing SCADA communications?
Virtual Private Networks (VPNs)
TLS/SSL encryption
Using default passwords
IPsec tunnels
Explanation - Default passwords are a security weakness; proper security uses unique credentials, VPNs, TLS, IPsec, etc.
Correct answer is: Using default passwords
Q.103 What does the term 'SCADA redundancy' typically refer to?
Having multiple identical components (e.g., servers, communication links) to ensure continuous operation if one fails
Running SCADA on a single computer
Using analog sensors only
Increasing the number of alarms
Explanation - Redundancy provides fault tolerance by duplicating critical elements.
Correct answer is: Having multiple identical components (e.g., servers, communication links) to ensure continuous operation if one fails
Q.104 Which of the following best describes a 'SCADA firewall rule' that permits only specific SCADA protocol traffic?
Allow all traffic on port 80
Allow traffic only on ports used by IEC 61850 (e.g., 102, 3000) and block everything else
Block all inbound traffic
Enable ping requests from any host
Explanation - Restricting ports to only those required for SCADA protocols reduces attack surface.
Correct answer is: Allow traffic only on ports used by IEC 61850 (e.g., 102, 3000) and block everything else
Q.105 Which of the following is a typical reason to use 'IEC 60870‑5‑104' over 'IEC 60870‑5‑101'?
To enable communication over TCP/IP networks rather than serial links
To increase the voltage rating of devices
To reduce the number of alarms
To operate without any encryption
Explanation - IEC 60870‑5‑104 is the network‑layer version, allowing IP‑based communication.
Correct answer is: To enable communication over TCP/IP networks rather than serial links
Q.106 In SCADA, what does the term 'alarm flood' refer to?
A large number of simultaneous alarms that can overwhelm operators and mask critical events
A sudden increase in power generation
A rapid increase in data storage capacity
A method of encrypting communications
Explanation - Alarm flooding can cause alarm fatigue, making it harder for operators to identify true emergencies.
Correct answer is: A large number of simultaneous alarms that can overwhelm operators and mask critical events
Q.107 Which of the following is a common method for validating SCADA data integrity before it is used for control actions?
Applying checksum or CRC verification on received packets
Increasing the sampling interval
Disabling all encryption
Storing data without timestamps
Explanation - Checksums/CRCs detect transmission errors, ensuring data integrity before processing.
Correct answer is: Applying checksum or CRC verification on received packets
Q.108 What is the typical role of a 'SCADA engineering workstation'?
To configure system parameters, develop control logic, and test communications
To physically switch circuit breakers
To generate electricity
To provide backup power to the grid
Explanation - Engineering workstations are used for system design, configuration, and testing, not for direct control.
Correct answer is: To configure system parameters, develop control logic, and test communications
Q.109 Which of the following best explains why 'SCADA systems often use separate dedicated networks'?
To isolate critical operational traffic from corporate IT traffic, improving security and performance
Because SCADA cannot operate over Ethernet
To reduce the need for firewalls
To increase the number of field devices
Explanation - Segregated networks reduce risk of interference and cyber‑attacks from less secure IT domains.
Correct answer is: To isolate critical operational traffic from corporate IT traffic, improving security and performance
Q.110 Which of the following is a typical feature of a SCADA 'event log'?
Chronological record of system events, alarms, and operator actions with timestamps
Real‑time voltage waveform display
Automatic generation of new hardware
Physical storage of spare parts
Explanation - Event logs provide audit trails and support post‑incident analysis.
Correct answer is: Chronological record of system events, alarms, and operator actions with timestamps
Q.111 Which of the following best describes a 'SCADA soft‑switch'?
A software‑based virtual circuit breaker that can be opened or closed via control commands
A hardware device that converts AC to DC
A type of alarm with low priority
A backup power supply for RTUs
Explanation - Soft‑switches emulate physical switching actions within software, often used in simulations or protective schemes.
Correct answer is: A software‑based virtual circuit breaker that can be opened or closed via control commands
Q.112 Which of the following is a common technique for reducing the bandwidth consumption of SCADA telemetry data?
Event‑driven reporting (send data only on change)
Increasing the polling frequency to 100 Hz
Using uncompressed raw data streams
Duplicating all data packets
Explanation - Sending data only when values change beyond thresholds reduces unnecessary traffic.
Correct answer is: Event‑driven reporting (send data only on change)
Q.113 What does the abbreviation 'HMI' stand for in SCADA terminology?
Human‑Machine Interface
High‑Memory Integration
Hybrid Modbus Interface
Hardware Monitoring Instrument
Explanation - HMI provides the graphical interface through which operators interact with the SCADA system.
Correct answer is: Human‑Machine Interface
Q.114 Which of the following is a common cause of 'SCADA false data injection' attacks?
Compromised RTU firmware that modifies measurements before sending them
Using fiber‑optic cables
Running the HMI on a modern operating system
Increasing the sampling rate
Explanation - If an attacker gains control of firmware, they can alter sensor data before transmission, leading to false data injection.
Correct answer is: Compromised RTU firmware that modifies measurements before sending them
Q.115 Which of the following best defines the term 'SCADA command latency'?
The time between an operator issuing a command and the field device executing it
The storage capacity of the historian
The number of alarms generated per day
The voltage level of a transmission line
Explanation - Command latency measures the responsiveness of the control loop from user action to field actuation.
Correct answer is: The time between an operator issuing a command and the field device executing it
Q.116 In IEC 61850, what is the purpose of the 'Sampled Values (SV) Sub‑Network'?
To transmit high‑speed sampled analog measurements over Ethernet
To provide a backup power source
To store configuration files
To manage user authentication
Explanation - SV Sub‑Network carries synchronized voltage and current samples for protection and control.
Correct answer is: To transmit high‑speed sampled analog measurements over Ethernet
Q.117 Which of the following best explains the use of 'IEC 62351‑3' in SCADA systems?
It defines security mechanisms for authenticating and encrypting IEC 61850 communications
It sets standards for transformer design
It specifies the physical dimensions of RTUs
It governs the pricing of electricity
Explanation - IEC 62351‑3 provides security extensions for IEC 61850, ensuring confidentiality and integrity.
Correct answer is: It defines security mechanisms for authenticating and encrypting IEC 61850 communications
Q.118 Which of the following is a typical benefit of implementing 'edge analytics' in SCADA for a smart grid?
Real‑time detection of anomalies close to the source, reducing central processing load
Eliminating the need for any central control center
Increasing the number of field devices required
Providing free Wi‑Fi to customers
Explanation - Edge analytics processes data locally, enabling faster response and reducing bandwidth to the central system.
Correct answer is: Real‑time detection of anomalies close to the source, reducing central processing load
Q.119 Which of the following protocols is specifically designed for process control and is widely used in SCADA for data acquisition?
Modbus
HTTP
SMTP
FTP
Explanation - Modbus is a simple, open protocol used extensively for reading and writing data to field devices.
Correct answer is: Modbus
Q.120 In a SCADA system, what does the term 'heartbeat timeout' indicate?
The maximum time allowed between successive heartbeat messages before the link is considered lost
The duration of a power outage
The interval between operator logins
The time required to compress data
Explanation - If a heartbeat is not received within the timeout, the master assumes the remote device is offline.
Correct answer is: The maximum time allowed between successive heartbeat messages before the link is considered lost
Q.121 Which of the following is a common practice to ensure 'SCADA data integrity' during transmission?
Using CRC or checksum fields in protocol frames
Sending data without any headers
Running the system on a public Wi‑Fi network
Disabling all firewalls
Explanation - Error‑detecting codes like CRC verify that data has not been corrupted in transit.
Correct answer is: Using CRC or checksum fields in protocol frames
Q.122 What is the primary advantage of using 'IEC 60870‑5‑104' over a legacy serial protocol in modern SCADA deployments?
It enables IP‑based communication, facilitating integration with Ethernet networks
It reduces the need for any security measures
It works only with proprietary hardware
It eliminates the need for data historians
Explanation - IEC 60870‑5‑104 uses TCP/IP, making it easier to integrate with existing IT infrastructure.
Correct answer is: It enables IP‑based communication, facilitating integration with Ethernet networks
Q.123 Which of the following best describes the term 'SCADA topology'?
The physical layout and logical arrangement of devices and communication links in the SCADA network
The voltage level of the transmission system
The color scheme of the HMI screens
The brand of the RTUs used
Explanation - Topology defines how components are connected and interact within the SCADA architecture.
Correct answer is: The physical layout and logical arrangement of devices and communication links in the SCADA network
Q.124 Which of the following is an example of a 'soft‑real‑time' requirement in a SCADA control loop?
A control action must be executed within 2 seconds, but occasional slight delays are tolerable
The system must never miss a deadline under any circumstances
All data must be processed within 1 µs
The system must operate without any communication
Explanation - Soft‑real‑time allows occasional deadline misses without catastrophic consequences.
Correct answer is: A control action must be executed within 2 seconds, but occasional slight delays are tolerable