Exercises: Supervision and monitoring

Explain in your own words what a SCADA system does and what the words in its acronym stand for (supervisory control and data acquisition). Give an example of a facility where it is essential.

Explain what telemetry is (measuring remotely and sending data) and describe an everyday or familiar example where measurements sent automatically over a network are used, indicating what is measured and who receives the data.

What advantages does supervising a water treatment plant from a remote control room offer compared to walking around inspecting it on foot? Name at least three advantages and justify each one (response speed to failures, historical records, staff safety, etc.).

Explain what an alarm is in a SCADA system, what two states it can have (active, acknowledged), and why acknowledging an alarm is not the same as resolving it.

A remote setpoint allows changing a reference value from the control room. Give an example (changing the temperature of a climate-controlled hall from the central control) and describe the path this command takes to the actuator.

SCADA stores historical data for all variables. Explain the purpose of checking data from months ago (finding when a fault started, planning maintenance before a failure) using a concrete example.

The mimic screen represents the plant schematically with live values. Explain the advantages of viewing the plant in this way, rather than looking only at data tables (locating each value on its machine, detecting anomalies at a glance).

Distinguish between a plant operator (inspects machines) and a control room operator (monitors screens): what each person sees and does, and why both roles remain necessary in a large facility.

The diagram shows the supervision of an industrial plant: sensors and PLCs in the plant send their data through an intermediate element to the supervisory station, where an operator monitors graphs and alarms, as shown in the diagram.

State which element is missing between the plant and the supervisory station, explain what type of information travels in each direction, and describe what the operator sees and can do when an alarm is triggered.

A SCADA screen typically displays current variable values, trend graphs, and alarms. Explain what each of these three elements provides to the supervisor and what decisions can be made with each one (taking immediate action, anticipating a fault, adjusting setpoints, etc.).

Distinguish between monitoring a process (observing and recording it) and controlling it (acting upon it). Explain why a SCADA system typically does both and give an example of a supervisory action and a control action in a city's water supply system.

Many variables can be measured in a municipal water storage tank. Choose four (level, inlet flow rate, outlet flow rate, network pressure, chlorine concentration, etc.) and define an alarm for each with a reasonable threshold and the required action, justifying your choices.

Smart water or electricity meters send their readings via telemetry. Explain what data they send and how frequently, and what problems can be detected by analysing them (a leak consuming water in the early hours, a broken meter, anomalous consumption patterns).

When an alarm is triggered, the system requires the operator to acknowledge it. Explain what is recorded with this acknowledgement (who saw it and when), why it is important for accountability, and what risk is posed by the habit of acknowledging alarms without looking at them.

A company supervises 50 remote stations from a single control center. Analyze what changes compared to supervising a single local plant (reliance on communications, prioritization of alarms arriving from multiple sites, minimum duty staff) and what minimum redundancy you would require for the communications network.

A critical alarm (for instance, overpressure in a boiler) should not rely on a single sensor. Explain what safety instrumentation is (measurement and control chains independent of the main control system) and why it is designed separately from the SCADA system that supervises the process.

In the SCADA system of a 10 MW photovoltaic solar park, at clear midday you observe the following readings: the pyranometer indicates 950 W/m², the ambient temperature is 32 °C, but the set of inverters in sector B delivers only 40 % of its rated power while the internal temperature of its semiconductors reaches 82 °C (compared to 58 °C in the rest of the park). No alarm has triggered because only alerts for sudden current loss were programmed.

1. a) Diagnose what technical cause or anomaly might be affecting sector B and justify which two new alarms (indicating monitored variable, condition or quantitative threshold, and priority level) you must configure in the SCADA system to prevent equipment damage.
2. b) Design two remote control or automatic control actions that the control room operator must be able to execute from the SCADA system to mitigate overheating without leaving the sector completely disconnected.

During the commissioning of a chemical reactor, 140 alarms are recorded on the SCADA console in just two minutes. Hidden within the continuous list of pop-up events is a critical warning of a pressure drop in the cooling circuit that the operator overlooks while trying to silence the acoustic alerts, causing an overtemperature trip.

1. a) Diagnose the design problem that causes this "alarm flood" and justify why treating any sensor state change as an alarm undermines the operator's supervisory role.
2. b) Design a technical solution for the SCADA system based on three mechanisms: dynamic alarm suppression according to the operating phase, hierarchical prioritisation, and deadband or hysteresis filtering. Explain how each of these mechanisms would act during a start-up transient to prevent operator overload.

A group of cyberattackers manages to infiltrate the corporate network of an electricity distribution company and attempts to manipulate substations through a data spoofing attack targeted at the SCADA system. The goal is to inject false voltage and temperature values into the HMI interface to deceive operators while physically overloading the transformers.

1. a) Predict the technical and operational impact of this attack on grid stability if operators make decisions based on falsified readings before local electromechanical protections trip.
2. b) Design an industrial cybersecurity architecture proposal based on the ISA/IEC 62443 standard: justify the separation between IT and OT networks using zones, conduits, and an industrial DMZ, and explain what role a data diode or unidirectional gateway plays in protecting infrastructure supervision.

In a 2.5 km road tunnel with heavy rush-hour traffic, the SCADA system simultaneously records in the middle sector: CO concentration of 85 ppm (normal value < 30 ppm), environmental opacity of 38 %, average traffic speed of 0 km/h, and a sharp temperature rise of 15 °C/min at kilometer 1.2 according to the linear heat sensor cable.

1. a) Interpret the correlation of these data, determine the origin of the event, and establish with reasoning the priority order with which the system must handle the generated alarms.
2. b) Design the automated and remote response sequence that the SCADA system must command to the field actuators: longitudinal or semi-transverse ventilation (smoke control), cross/arrow lane signalling panels, and closure barriers at the tunnel portals, justifying the chronological order of activation to ensure the survival and evacuation of tunnel users.

Communications fail between a water treatment plant and the SCADA center supervising it. Analyze which functions must continue operating autonomously at the plant (local control loops and protections), what must never depend on the network (the emergency stop), and how data are resynchronized when communication is restored.

On the supervisory HMI screen of an industrial steam boiler, the following warnings coincide within an interval of a few seconds:

1. Preventive maintenance warning: 5000 operating hours of the burner reached.

2. Open analog input (4-20 mA loop failure) on the secondary flue gas temperature probe.

3. Burner access hatch microswitch open.

4. Boiler drum water level at 12% (minimum safety level: 25%).

5. Steam pressure at 18.2 bar (working pressure: 14 bar; mechanical valve trip: 19 bar).

6. Steam outlet temperature at 235 °C (nominal temperature: 210 °C).

1. a) Evaluate the severity and urgency of each event from the perspective of physical risk to the facility and determine which one requires the immediate automatic trip (interlock) of the fuel supply even before operator intervention.
2. b) Design the alarm hierarchy in the SCADA by classifying them into three levels (Critical, Major, Informational) and propose three ergonomic HMI design criteria (color coding, visual segregation, or acoustic management) to ensure that critical alarms stand out immediately without being masked by the others.

A security audit at a drinking water treatment plant detects that the PLCs controlling chlorine dosing and discharge pumps are on the same IP subnet as the administration computers, and that the manufacturer has permanent remote access without two-factor authentication to apply live software patches.

1. a) Analyze the attack vectors opened by this configuration: predict what could happen if an office computer is infected with malware or if an attacker exploits remote access to modify the disinfection setpoints in the PLCs.
2. b) Justify why in industrial automation environments (OT networks) the deployment of patches and updates cannot be automated as in office computers (IT networks), analyzing the concepts of uninterrupted availability, real-time determinism, and the need for prior validation on test benches or digital twins.

In a robotic palletizing cell supervised by a SCADA, a technician enters the enclosure to retrieve a dropped box by crossing a safety light curtain. As he bends down to pick up the part, a coworker presses the virtual "Resume cycle" button from the SCADA HMI screen and the robot resumes movement, causing a near-miss incident.

1. a) Analyze why allowing the robot to be reset directly from the remote SCADA screen constitutes a serious machine safety violation and describe how the safe reset circuit must be designed (location of the physical reset button, visibility of the interior of the cage, and function of the dual-channel safety relay).
2. b) Design the representation on the SCADA HMI screen for this cell: explain how the system status should be displayed in three different situations (operational stop due to end of batch, emergency stop tripping, and light curtain interruption) and what logical conditions the system must verify before allowing any startup sequence.