A Uninterruptible Power Supply (UPS) or standby generator connected to dedicated final circuits of the distribution infrastructure. Enhance the infrastructure resilience and can improve maintenance opportunities and business continuity for the higher risk areas.  

Typical tertiary power supplies:

• batteries for UPS systems, inverter units and generators;
• HV/LV tripping/closing batteries;
• UPS systems;
• inverter units for central battery units and theatre operating lights.

Tertiary power supplies should not be used as a long-term energy source in the same way that primary supplies or
secondary supplies.