74 MaintenanceIf you change any wirings or components after the start-up, replacethe FPTC-01 module, modify drive or FSO parameters or restoreparameters to their factory default values, you must:• Use only ABB approved spare parts.• Register the change to the change log for the safety circuit orlogbook of the machine.• Test the safety function again after the change. Obey the rulesgiven in chapter Start-up and acceptance test.• Document the tests and store the report into the logbook of themachine.Proof test intervalAfter the operation of the safety function is validated at start-up, thesafety function must be maintained by periodic proof testing. Inhigh demand mode of operation, the maximum proof test interval is20 years. In low demand mode of operation, the maximum prooftest interval is 2 years (high or low demand as defined inIEC 61508, EN/IEC 62061 and EN ISO 13849-1). Regardless ofthe mode of operation, it is a good practice to check the operationof the safety function at least once a year. Do the test as describedin chapter Start-up and acceptance test.The person responsible for the design of the complete safetyfunction should also note the Recommendation of UseCNB/M/11.050 published by the European co-ordination of NotifiedBodies concerning dual-channel safety-related systems withelectromechanical outputs:• When the safety integrity requirement for the safety function isSIL 3 or PL e (cat. 3 or 4), the proof test for the function mustbe performed at least every month.• When the safety integrity requirement for the safety function isSIL 2 (HFT = 1) or PL d (cat. 3), the proof test for the functionmust be performed at least every 12 months.