Burned wires on resistance faston connection on professional Coffe machine

[light767]

Hi all

I have a professional coffe machine working at 220 V and it currently drain about 2,5 kW of power. I have made this simple and horrible schematic here just to explain how it works:

Some time ago I changed the fastons on the resistance from brass faston to stainless steel faston and some time after, this is what happen:

As you can see the wire on the bottom is completely burned and as I did not notice that immediately also the general switch and the safety thermostast get damage. So I changed the general switch, the safety thermostat and cutted the burned wire so I put everything back toghether.
I did a full restoration of the machine but I did not change the eletrical wires because they looked good ( they are industrial ones and have a 2.5 mm^2 section ) even if they hare 20 years old now.
Now this happen again on the other side:

I'm wondering if this can be related to the stainless steel material of the faston that maybe can produce and overheating due to the fact that the electrical condutivity of the stainless steel it's worst then the one of the brass faston. This never happen with brass faston. So what do you think?

 

[OLDBOY]

Hi all

I have a professional coffe machine working at 220 V and it currently drain about 2,5 kW of power. I have made this simple and horrible schematic here just to explain how it works:
View attachment 113059
Some time ago I changed the fastons on the resistance from brass faston to stainless steel faston and some time after, this is what happen:

View attachment 113060

As you can see the wire on the bottom is completely burned and as I did not notice that immediately also the general switch and the safety thermostast get damage. So I changed the general switch, the safety thermostat and cutted the burned wire so I put everything back toghether.
I did a full restoration of the machine but I did not change the eletrical wires because they looked good ( they are industrial ones and have a 2.5 mm^2 section ) even if they hare 20 years old now.
Now this happen again on the other side:


View attachment 113062

I'm wondering if this can be related to the stainless steel material of the faston that maybe can produce and overheating due to the fact that the electrical condutivity of the stainless steel it's worst then the one of the brass faston. This never happen with brass faston. So what do you think?

It will be caused by the terminations not being secure, it may be that the SS ones you have fitted are not as good fit on the terminals as the originals.

 

[Marvo]

Some fast-on terminals have a higher current rating than others, you need to see the datasheet for the particular brand you're using; I've seen 6.3mm female fast-on terminals with a 5Amp rating as well as 10 Amp and I'm guessing this is because they're made of thinner material. Also avoid cheap Chinese items from ebay and amazon like the plague and wherever possible use a crimping tool that's the same manufacturer as the terminals. We always use Hellermann Tyton or BM crimps and crimping tools and have never had problems.

 

[James]

A crimping tool that is designed for copper terminals, may well not put enough pressure on the terminal to hold the cable correctly if used with stainless steel terminals as they are considerably harder to deform.