Cable harness with fuse

General Electronics
1

Hi

I am working on a product that has a problem with a relay output that has no fuse. and during CE approval, conforming to IEC60730 the outputs are loaded with 25A (230V), which destroys the PCB. Track that opens and arcing afterwards

So, I am exploring different possibilites. One quick fix is to add external harness with an inline fuse (fuse needs to be heatshrink wrapped to provide double insulation)

We need some input, so either a consultant that has experience, or input from where to buy harness with inline fuses.

We can use EU firms, US or Asian. Whatever is best and quickest is preferred (product launch is delayed due to this)

Any inputs are highly welcome :slight_smile:

Regards

Klaus

2

Which class of iec 60730 are you looking to apply and which test are you performing?

From there it would be helpful to know what the funcion of the relay is and why it is considered part of the test.

It sounds like it is the provision for protective earthing test - clause 9.

Could you please confirm thats the test and then hopefully i might be able to assist further.

3

Have you looked at something like this: https://www.digikey.com/en/products/detail/littelfuse-inc/01500274Z/29453

Would not require much engineering to put some rated heat shrink over the top of this if the holder does not already qualify for double insulation.

There is a plethora of In Line fuse holders out there if that particular one does not fit the bill: https://www.digikey.com/en/products/filter/fuseholders/140?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIAzACxwBMdIAuoQA4AuUIAymwE4CWAOwDmIAL4SgA

4

It’s 60730 section 27.5, abnormal operation, so overload of output. In principle we have mains input with a breaker box fuse of 16A. This is fed through a relay to an output

The standard defines 1 hour overload. We need to multiply 16A with 1.6 due to the fuse can handle that current for 1 hour. During the test the PCB/relay cannot have more than 1.5*130degrees = 195 degrees, to comply. Also, no fire must occur

5

Yes, we have looked at that. It’s about 5000 units we need to make, so that could be an option until we have modified the PCB to have a fuse

I have also considered to add a NTC to measure the temperature next to the relay, or even measure the output current, and turn it off if it gets too high

If the current is high, and the relay opens, there are voices in the team that claim we will destroy the relay due to arcing. But since it is ac, I am not sure about this. Seems it would be a nice small test to do