How often must a Central Power Supply System be tested?

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.