Reliable power for a sustainable world
What’s The Difference Between A Central Power Supply System And A UPS?

Central Power Supply Systems (CPSS) are a specific type of standby power solution used with emergency and safety-related applications such as lighting, alarms and security systems.

Also known as Central Supply Systems (CSS), they share many of the design and operational features of a typical online UPS. 

To be classified as a CPSS, the product must meet the strict criteria outlined in EN 50171 for use with essential safety systems. This standard covers emergency systems permanently connected to AC supply voltages not exceeding 1,000V that use batteries as an alternative power source.  

CPS systems are used to power a broad range of emergency-related applications and devices in the event of a mains failure: 

  • Emergency lighting 
  • Fire safety and prevention i.e. fire extinguishers, smoke extractors, lifts 
  • Alarms and other detection systems 
  • Warning systems such as carbon monoxide detectors 
  • Safety signs and other signalling installations 


A standard online UPS is unlikely to meet the requirements of EN 50171 and should not be used for such critical emergency applications. However, some specially-designed emergency UPS models do meet the strict criteria. In effect, these solutions are expressly configured for a specific task/environment. 

Central Power Supply Systems require a combination of resilience, regulatory compliance, and ease of use. To meet these objectives, Riello UPS’s emergency UPS typically incorporate the following features: 

  • Battery autonomy up to three hours or longer if necessary (at least one hour if there is an on-site generator)
  • Short battery recharge times (typically 80% capacity within 12 hours) 
  • Deep battery discharge protection
  • Sophisticated battery monitoring and battery care systems 
  • Optional Galvanic isolation of the input and output 
  • High short circuit (in-rush) current capacity (particularly with emergency lighting installations)
  • Advanced diagnostics accessible through user-friendly display panel 


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