EN81-72, BS9999 and EN81-76 RELIABLE BACKUP POWER FOR LIFTS
SECONDARY POWER SUPPLIES
Our high-performance secondary power systems keep lifts operational during power outages, ideal for firefighting and evacuation lifts in residential, commercial, and industrial settings.
PRODUCT OVERVIEW
Our system delivers full elevator functionality during blackouts, enabling safe evacuation over extended periods.
✓ Compliant with BS9999, EN81-72 and EN81-76:2025
✓ Suitable for both new and existing installations
✓ Integrated with any controller, no special cabling required
✓ Fully customisable duration (1–4 hours, or by trips etc.)
✓ Easy installation, low-maintenance battery packs
✓ Supports regenerative energy for extended performance
HOW IT WORKS
The system supplies:
✓ 600 VDC for the VF drive
✓ 230 VAC for brakes, controller, and door operators
✓ Real-time battery level monitoring from the controller
✓ Energy regeneration: stores lift-generated energy for reuse
✓ Low input to maintain charge
✓ Compact 48V battery packs, low cost and easily replaceable
✓ The batteries are subjected to small, fully automatic daily cycles to ensure proper maintenance, allowing easy monitoring of the batteries.
TECHNICAL SPECIFICATION
The DSW Emergency Evacuation System is an auxiliary power supply designed to support lift evacuation and firefighter operation in accordance with EN81-72 (Firefighting lifts) and EN81-76 (Evacuation of persons with disabilities) requirements. The system ensures full continued availability of a lift during total mains power failure, allowing repeated evacuation trips under controlled conditions.
The product supplies regulated 600 VDC to the lift VVVF drive and 230 VAC to auxiliary and safety-critical circuits, including controller electronics, brakes, door operators, and lighting. Power is delivered from a centralised 48 V battery system, continuously monitored and offering real-time communication to the lift controller including real-time state-of-charge battery feedback.
This closed-loop communication enables the controller to manage evacuation logic without risk of mid-travel power loss, ensuring compliance with trapping prevention requirements defined in EN81 standards.
The system incorporates regenerative energy recovery, capturing braking energy generated during lift motion and returning it to the battery bank, thereby even extending evacuation availability and improving system efficiency from the minimum statutory requirements.
The system integrates directly with the new or existing lift controller, providing continuous battery state-of-charge data to prevent trapping and ensure safe evacuation sequencing.
COMPARISON TABLE
Category | Criterion | DSW Power Solution | Diesel Generator | Traditional UPS |
|---|---|---|---|---|
Functional Scope | Primary Purpose | Sustained/extensive lift evacuation during mains failure | Whole-building emergency power | Short-duration backup for electronics |
Lift Drive Supply | Direct 600 VDC supply to VVVF lift drive | Indirect | Typically not suitable for large traction drives | |
Control & Auxiliary Supply | Dedicated 230 VAC for controller, brakes, doors, auxiliaries | Supplied via building electrical panels | Limited, often undersized | |
Number of Evacuation Trips | Multiple, configurable trips | Unlimited (fuel dependent) | Usually single rescue trip | |
Evacuation Strategy Support | Full evacuation and assisted evacuation | Full evacuation possible | Passenger release only | |
Controller Integration | Native integration, controller retains full logic | Indirect, building-level | External, limited interaction | |
State-of-Charge Feedback | Real-time feedback to lift controller | Not applicable | Rare / typically none | |
Regenerative Energy Recovery | Yes, braking energy stored | No | No | |
Risk of Trapping Mid-Trip | Actively managed | Low once generator is stable | Medium to high | |
Response Time to Power Loss | Instantaneous | Delayed (start-up and stabilisation) | Instantaneous | |
EN81-72 / EN81-76 Alignment | Designed for compliance | Conditional | Generally not compliant | |
Installation & Infrastructure | Installation Complexity | Low, localised near controller | High (civil, mechanical, electrical) | Low to moderate |
Retrofit Suitability | Excellent | Poor to moderate | Moderate | |
Space Requirements | Compact cabinet | Large plant room + fuel storage | Compact to moderate | |
Ventilation Requirements | No forced ventilation required | Mandatory forced ventilation & exhaust | None | |
Exhaust / Emissions | None | Diesel exhaust, NOx, particulates | None | |
Noise Levels | Silent | High, often requires mitigation | Silent | |
Fire & Environmental Risk | No combustible fuel | Fuel storage, spill and fire risk | Low | |
Operational & Maintenance | Routine Maintenance | Low (battery monitoring) | High (engine & fuel systems) | Moderate |
Operational Testing | Automatic self-testing | Mandatory load-bank testing | Manual testing | |
Energy Consumption (Standby) | Very low | High | Moderate | |
Fuel Dependency | None | Continuous fuel supply required | None | |
Life-Cycle Cost (20 Years) | Initial CAPEX | Medium | High | Low |
Design & Engineering Costs | Low | High | Low | |
Planning & Regulatory Costs | Minimal | High | Minimal | |
Installation Costs | Low | Very high | Low to moderate | |
Replacement Cycle | Batteries every 8–12 years | Engine overhaul 10–15 years | Batteries every 4–6 years | |
Battery / Fuel Costs | Predictable, moderate | High and volatile | Moderate to high | |
Ventilation & Exhaust Costs | None | High (installation + energy use) | None | |
Noise Mitigation Costs | None | Often required | None | |
Environmental / Carbon Exposure | None | Increasing regulatory risk | None | |
Downtime / Business Risk | Low | Medium to high | Medium | |
Total OPEX (20 Years) | Low | Very high | Medium | |
Total Cost of Ownership | Lowest | Highest | Medium |
Input Power
450 – 1500 W
Energy Storage
As required
Nominal Output (Drive)
3500 – unlimited
Controller Integration
Native, no additional logic
Max Output (Drive)
4000 – 1.2x nominal
Power Source
From 4 x 12v batteries / supercapacitors
COMPLIANCE & SAFETY
EN 81-76:2025 introduces new inclusive evacuation modes:
✓ Driver-Assisted Evacuation – A trained operator aids in evacuation
✓ Automatic Evacuation – The lift functions autonomously in emergencies
✓ Remote-Controlled Evacuation – A technician operates the lift remotely
These standards ensure inclusive, reliable evacuation in all building types with direct implications for building design, fire strategy, and regulatory compliance. A LEIA BS EN 81-76:2025 guidance note can be read here: EN81-76.
IDEAL FOR
COMMON USE CASES
Power failures during emergencies
Buildings with firefighting lift requirements
Retrofits where minimal cabling is required
Sustainability & safety upgrades
REAL CASE STUDIES
