RS485 stand to meet the EFT (Electrical Fast Transients) test according to IEC 60601

[Nissim Shaked]

Dear team,

Our RS485 is communicating between 2 systems (DCU communicate/control with the RF SW box), with RS485 protocol over 8 meter shielded 4 sinew wires cable.
We are developing a medical device and we need to communicate between the electronically Cage to the Peripheral electronically boxes model.
The communication is according to RS485.

Can someone provide us information which safety procedures/measures do new need to take, or what should we do for best complying with the EFT/IEC61000-4-4 test (part of the Immunity test ).

thanks

Nissim Shaked

 

[Pads38]

Re: RS485 stand to meet the EFT test according to 60601 test

For EFT your test requirements are + and - 2kV coupled to the power cable and, as your signal cable is more than 3m, + and - 1kV on the signal cable.

What is NOT allowed to happen: (the compliance criteria)
- component failure
- changes in programmable parameters
- reset to defaults
- change of operating mode
- false alarms
- cessation or interruption of operation
- initiation of unintended operation
- display error large enough to affect diagnosis or treatment
- noise large enough to affect diagnosis or treatment
- artifact large enough to affect diagnosis or treatment
- failure of an automatic system

(there is a fair bit of paraphrasing / abbreviation in that list so check clause 6.2.1.10)

You will also need to define "Essential Performance" for your device - this must be maintained during the tests.

 

[Nissim Shaked]

Re: RS485 stand to meet the EFT test according to 60601 test

The answer is what we should test to pass the EFT test.
My question is if data sheet of the device indicates that it is:
Robust +/-15kV ESD Protection (IEC 61000-4-2 Air Gap)
Is it automatically makes it EFT approved or it should be tested anyway.

 

[Pads38]

Re: RS485 stand to meet the EFT test according to 60601 test

Having components rated to 15kV (ESD) is good for confidence but the whole system needs testing - but only to 8kV (air).

A point to remember though;
The standard states + and - 8kV as the levels required but if you have particular risk of higher levels being likely to be encountered then you may need to go higher. Depends on your risk management.