EN60601-1 - Resettable fuses in a ME-device

D

Dimitri2

#1
Hello all,

EN60601-1 says a ME-device must have fuses. I'd like to avoid accessable fuse holders in the Class II device. The power entries for Class II normally have no built-in holders as those of Class I do.

May I use resettable fuses like LVR200S? (Pls google for it since I'm not allowed to add any links) I see a problem because they never disconnect for sure and for ever. They just reduce the current.

regards
Dimitri
 
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Peter Selvey

Staff member
Super Moderator
#3
It's not 100% clear, but 95% sure that a PTC device is not acceptable for Clause 8.11.15 (fuse/over-current release in the supply).

These devices are OK for protecting transformers, motors etc against overload and short circuit (if they meet required IEC standards).

However Clause 8.11.15 specifically mentions a device which creates an open circuit, and these PTC devices do not actually create a real break like a fuse or circuit breaker does. The spec sheet also advises against use in this kind of situation.
 
D

Dimitri2

#4
Thank you Peter. It sounds reasonable. However, I never saw "medical-grade" panel-mounted fuse holders except those associated with Class I power entry whereas it is not possible to exchange them with MAINS cable still attached.

Well, I might put a pair of fuse holders onto the PCB inside and then gather the statistics after how many switch-ons they'll burn.
 

Peter Selvey

Staff member
Super Moderator
#5
It's normal to have the fuse inside the equipment, there is no requirement that it must be accessible from the outside or even replaceable. It can be one of those small round PCB mount fuses near the L-N terminal on the PCB. If it blows the device can be throwaway or return to supplier for repair.

Also for Class II devices, you only need one fuse.
 
D

Dimitri2

#7
I remember having read in a "tutorial book" of the German TUV that it is allowed to use the Class I power entry module (with PE line) in a Class II ME-device IF the PE is not connected at all. Even in the cable? (which is not possible)

Would someone please share his thoughts on this issue.

Thanks.
 

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