UPS
Introduction
A UPS (Uninterruptible Power Supply) is a system that temporarily powers electrical equipment from a Backup source when the primary supply fails or becomes unstable. UPS systems are deployed to protect critical equipment against outages, surges, sags, harmonic distortion and other electrical disturbances.
In OT and IT environments, UPS systems are essential for safeguarding availability, reliability and safe shutdown procedures. They are widely used in:
- Data centres
- SCADA environments
- PLC installations
- DCS systems
- Telecom infrastructure
- Hospitals
- Critical infrastructures
- Industrial Automation
UPS systems are a key element of Business Continuity, High Availability and industrial resilience strategies.
⚡ How a UPS works
A UPS continuously monitors the mains supply and switches automatically to battery power when:
- Mains voltage drops out
- Voltage moves outside tolerance
- Frequency becomes unstable
- Voltage spikes occur
The basic components are:
| Component | Function |
|---|---|
| Rectifier | Converts AC to DC |
| Battery | Temporary energy storage |
| Inverter | Converts DC to AC |
| Bypass | Direct mains feed on fault |
| Controller | Monitoring and switching |
On power loss the battery instantly supplies energy to the connected equipment.
🔋 UPS types
Offline UPS
The load runs directly off the mains in normal operation.
On power loss the UPS switches to battery power.
Characteristics
- Low cost
- Simple Architecture
- Short transfer time
- Basic protection
Applications
- Workstations
- Small office environments
- Non-critical systems
Line-interactive UPS
Provides voltage regulation without immediately drawing on the batteries.
Characteristics
- Better voltage correction
- Higher efficiency
- Less battery wear
Applications
- Small server rooms
- Network equipment
- Industrial edge systems
Online UPS
The load is continuously powered through the inverter.
Characteristics
- No transfer time
- Full voltage conditioning
- Highest availability
- Best protection
Applications
- SCADA
- DCS
- Data centres
- Critical OT systems
- Process Automation
🏭 UPS in industrial automation
Within Industrial Automation, UPS systems protect critical equipment against unexpected outages.
Protected systems
| System | Reason |
|---|---|
| PLC | Prevent production stoppage |
| SCADA | Continuous process visibility |
| Historian | Prevent data loss |
| Industrial Switch | Network availability |
| Firewall | Cybersecurity continuity |
| HMI | Maintain operator control |
| DCS | Process safety |
UPS systems are typically combined with:
- Redundancy
- Generators
- Dual power feeds
- Industrial power supplies
🧠 UPS and OT availability
UPS systems play a key role in:
In OT environments even very short voltage interruptions CAN lead to:
- Production loss
- Safety incidents
- Damaged equipment
- Process instability
- Loss of synchronisation
🔄 UPS and Redundancy
Critical infrastructures often use redundant UPS configurations.
Common configurations
| Configuration | Description |
|---|---|
| N | Single UPS |
| N+1 | Extra redundant UPS |
| 2N | Fully duplicated infrastructure |
| 2N+1 | Extra redundancy on top of duplicated setup |
Redundancy reduces single points of failure in critical environments.
📡 Monitoring and management
Modern UPS systems support extensive monitoring functionality.
Monitored parameters
| Parameter | Example |
|---|---|
| Battery status | Capacity and health |
| Load level | Power consumption |
| Input voltage | Power quality |
| Temperature | Battery condition |
| Runtime | Expected backup time |
| Alarms | Faults and warnings |
Integration is typically over:
Monitoring data is fed into:
🔐 UPS Cybersecurity
Modern UPS systems are increasingly network-connected, which makes them a potential attack surface.
Possible risks
| Risk | Impact |
|---|---|
| Unauthorised access | Settings manipulation |
| Firmware attacks | UPS compromise |
| Network outage | Loss of monitoring |
| Ransomware | Management outage |
| Weak authentication | Management interface abuse |
Key Security measures:
UPS systems are often placed in separated OT Network segments.
🔥 Battery technologies
UPS systems use various battery types.
| Battery type | Properties |
|---|---|
| VRLA | Widely used, low maintenance |
| Lithium-ion | High energy density |
| NiCd | High reliability |
| Flywheel | Short bridging time |
| Supercapacitors | Fast discharge |
Lithium-ion is gaining ground thanks to:
- Longer lifespan
- Lower maintenance cost
- Higher efficiency
- Compact form factor
⚙️ Runtime and sizing
UPS capacity is determined by:
- Power consumption
- Required bridging time
- System criticality
- Redundancy requirements
Examples
| Scenario | Runtime |
|---|---|
| Safe shutdown | 5–15 minutes |
| Generator bridging | 15–60 minutes |
| Full continuity | Several hours |
Sizing requires analysis of:
- Peak load
- Inrush currents
- Power factor
- Infrastructure growth
📈 Benefits of UPS systems
| Benefit | Explanation |
|---|---|
| Continuity | No immediate outage |
| Equipment protection | Less damage |
| Safe shutdown | Prevents data corruption |
| Power conditioning | Better power quality |
| Higher availability | Less downtime |
| Process safety | OT process stability |
⚠️ Limitations and considerations
| Limitation | Explanation |
|---|---|
| Battery wear | Regular maintenance required |
| Heat generation | Cooling needed |
| Limited runtime | Temporary backup power only |
| Cost | High initial investment |
| Footprint | Especially with large installations |
Battery ageing is a major cause of UPS failure.
🏭 Real-world example
An industrial production site uses an online UPS setup for:
On power loss:
- UPS systems take over immediately
- The generator starts automatically
- Critical OT systems stay online
- Production processes are stabilised in a controlled way
This prevents uncontrolled shutdowns.
📚 Relationship with other concepts
| Concept | Relation to UPS |
|---|---|
| High Availability | Continuity safeguarding |
| Redundancy | Improves availability |
| SCADA | Critical OT load |
| PLC | Process control |
| Business Continuity | Operational continuity |
| Disaster Recovery | Recovery strategy |
| Power Quality | Voltage stability |
| OT | Critical infrastructure |
🧾 Conclusion
UPS systems form a fundamental part of modern IT and OT infrastructures. They protect critical systems against power loss and provide continuity, stability and safe process operation.
Within IT OT Convergence the importance of UPS systems continues to grow due to increasing dependence on digital infrastructure, Real-time communication and Industrial Automation. Modern UPS solutions combine energy storage, Monitoring, Cybersecurity and Redundancy to maximise the availability of critical processes.