USB Connector Operator Protection (MOPP)

[UlikSulit]

Good day! I am finally happy that my search lead me to this forum. I really appreciate it. I have a question for a device that soon will undergo to a 60601-1 inspection and I hope someone can help me.
It is class II with type B applied parts, PSU with 2 MOPP, secondary circuits at 12Vdc, metallic enclosure and there is an usb connector for data transferring to the customers computer.
There are two independent PCB inside the device, one that contains the above mentioned PSU that powers a plate applied to the patient, the other PCB is indipendent and contains an USB hub board that will be powered directly from a computer , the frame of the usb connector is also contacting the frame of the enclosure which is metallic and not earthed. My question is what kind of insulation should the usb provide considering it will be just for operator use? The measurements of touch currents with mains applied on the usb will cause this test to fail since the enclosure of the device cotact the external frame of the usb connector, Can we skip this test providing appropriate instructions? Thank you for your effort and many regards!

 

[Stijloor]

A Quick Bump!

Can someone help?

Thank you very much!!

 

[Peter Selvey]

If it is a Type B applied part it could be difficult without an isolation barrier.

Is the USB connection intended for use while connected to the patient?

If no, it could be a technical pass, but then it would be good if the risk management also considers if the user ignores instructions and leaves the connection in place anyway.

That risk would then depend on the nature patient contact (impedance, duration, status of the patient etc).

 

[Velarde]

Type B Applied Parts must be isolated by at least 1 MOPP (1500V dielectric strength test minimum) from other parts, that includes USB Port.

 

[UlikSulit]

Thank you Peter , thank you Velarde. I am sorry if I am late, I have lost my hopes but fortunately you replied, and that is great. Following to your comments, there will be no contact with the patients between part that contain usb connector but in some situations the usb lead can be in close proximity. If we consider that only Operator will have access to the the USb I understand from your comments requirements of mains on SIP/SOP can be waived. Could ypu please advise to which caluse of the standard I can rely to waive this test? Waiting from you, many thanks!

 

[Velarde]

The patient (Applied Parts) must have two MOPPs from Mains Power Supply, and the Operator must have two MOOPs from Mains Power Supply too. If you install in your ME Equipment an USB port and it is electrically connected (not isolated) to Applied Parts (for example they have the same earths (electrically connected)), you decrease the protection to 1 MOPP because USB port provides 1 MOPP because it only have a basic isulation provided by PC (personal computer) power supply. Basically you will break the isolation of the patient. For that reason you need an extra 1 MOPP in order to isolate Applied parts from USB Port. Another thing is the possibility of risk. The isolation of PC Power supply may break, or an dangerous voltage could touch the USB port (its a ME Equipment, cautions could seem exagerated), it is a first defect condition. You need isolation betwen metallic enclosure not connected to earth an your USB Port, that is for Operator Protection. I think you can not avoid the test, you need isolation.
Best regards