A
AndrewJ
I am developing a medical device that requires 60601 approvals which includes a device specific risk which requires mitigation by an electronic interlock circuit (requiring user intervention before the next action). Based on section 13 I understand that this interlock has to be single fault safe so I have two independent interlocks which prevent the harm from occurring.
Each interlock is constructed from analogue and digital logic at 3V and I am space constrained so I need to use small components and ICs with lead spacing less than 0.5mm. Section 13.2.1 of BS EN 60601-1:2006 + A12:2014 states that during the application of the single fault conditions the normal conditions identified in 8.1 a) also have to be applied. Where the spacing between two PCB tracks is less than 0.5mm they do not comply with the creepage distance requirements in table 16. Do I need to consider a short between tracks which don't comply with the creepage distance requirements as normal conditions when considering device specific hazards under single fault conditions? It is not clear whether a short in this situation has to be considered a normal condition when not being applied to electrical hazards.
I have just found that Annex A for subclause 13.1.1 states that the requirements for creepage and clearance are not intended to be required at the circuit board level (where the spacing cannot be compromised). This suggests that I do not have to consider shorting traces on a PCB as normal conditions but I cannot see how this is clearly referenced in the main standard. Based on this can two PCB traces separated by 0.3mm be exempt from having to be considered as shorted as normal conditions when applying single fault conditions?
Any help would be greatly appreciated.
Each interlock is constructed from analogue and digital logic at 3V and I am space constrained so I need to use small components and ICs with lead spacing less than 0.5mm. Section 13.2.1 of BS EN 60601-1:2006 + A12:2014 states that during the application of the single fault conditions the normal conditions identified in 8.1 a) also have to be applied. Where the spacing between two PCB tracks is less than 0.5mm they do not comply with the creepage distance requirements in table 16. Do I need to consider a short between tracks which don't comply with the creepage distance requirements as normal conditions when considering device specific hazards under single fault conditions? It is not clear whether a short in this situation has to be considered a normal condition when not being applied to electrical hazards.
I have just found that Annex A for subclause 13.1.1 states that the requirements for creepage and clearance are not intended to be required at the circuit board level (where the spacing cannot be compromised). This suggests that I do not have to consider shorting traces on a PCB as normal conditions but I cannot see how this is clearly referenced in the main standard. Based on this can two PCB traces separated by 0.3mm be exempt from having to be considered as shorted as normal conditions when applying single fault conditions?
Any help would be greatly appreciated.