FAQs - Central Power Supply Systems
Central power supply systems used to provide emergency power to life safety systems in data centre buildings.
It is mandatory to regularly test and inspect a Central Power Supply System (CPSS) to ensure it will operate correctly during a mains power supply failure. EN 50171 defines regular functional tests to verify changeover to battery supply and correct operation of connected loads in conjunction with automatic testing. A full battery discharge or duration test must be carried out at least annually to ensure that the batteries can supply the connected load(s) for the rated emergency duration. It is also mandatory to record all tests with data retained for inspection when required.
A CPSS maintenance contract will ensure that a central power supply system is regularly inspected and tested to ensure reliability. The system will also require regular visual inspection of indicators and alarms, the battery condition and charge status, charger operation and a check the local area around the CPSS installation for airflow, ease of access and environmental conditions such as temperature and humidity which could impact battery life and operational performance. The battery set should also be inspected for signs of aging or damage (split or bulging cases, or white residue on the terminal connections) and should be replaced according to the battery manufacturer recommendations; typically years 7-8 for a 10year design life battery (the standard for an EN 50171 compliant system). All preventative and emergency maintenance visits, faults and corrective actions must be logged. All work on the CPSS should be performed by a suitably trained and certified electrical/battery engineer familiar with CPSS engineering and emergency power standards.
A CPSS must be installed in accordance with the Central Power Supply Standard BS EN 50171:2021, building electrical code BS 7671 (18th edition) and fire safety requirements specific to the building the system us to be installed within. Key considerations include selecting a suitable location with adequate ventilation, temperature and humidity environmental monitoring and control, and secure restricted access. The CPSS must be sized to support all the connected safety loads and for the required battery runtime period (from 1hour to 3hours). It is also importation to consider routing of power and interface cables, with clear labelling and usage of fire-resistant cabling to ensure safety compliance and overall long-term reliability.