Why are EVSE RCD's so costly?

Hi,
Why are offtheshelf EVSE RCDs so expensive...the cheapest i can find is £114...


They have to do 30mA AC imbalance, and 6mA DC detection, and mustn't be "Blinded" by high DC levels

I mean, isnt it true that you can "home-brew" a '30mA/6mA' Type B RCD with a $1's worth of components?

Flyback said:

isnt it true that you can "home-brew"

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Must include a NE555.

Think what savings not having to get safety approval from all those agencies. Not wait years for testing results.

Thanks, but all you have to do is test with eg a micrel EVSE tester that it trips out on >6mA DC, and >30mA "AC imbalance"....then you can start selling product...you can wait for the official standards approval.......get it later.

If you trip out and turn off when >30ma AC or >6mA DC then youre sorted....and you can start selling product.

These sort of circuits can be done for 50 cents worth of components...ive seen it with my own eyes....why do people not do this?

Admittedly for international sales (outside your own country), then you really do start to need the official approvals.

Let me know what you design. I shall avoid those items.

Flyback said:

I mean, isnt it true that you can "home-brew" a '30mA/6mA' Type B RCD with a $1's worth of components?

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I'd like to see you get a 40A contactor with 10,000A break capability for one dollar!

It's no use unless it can be guaranteed to break the circuit under the most extreme fault conditions, such as a shorted cable.
"10 kA" is a typical break capacity rating for Type B RCDs.

At teh same time, the device must NOT trip on brief transient high current spikes.

Thanks, but sorry i should have said, i am not talking of the contactor.........i am only speaking about the signal circuit of the "30mA/6mA" RCD.

We can add the contactor ourselves, and yes, i agree, this would be more than a few dollars

Why is it that we cant make an 32A RCD "fluxgate current sensor" for a 32Arms mains distributon box without using feedback, and without using a square law core? (ie , just use a standard CT core instead). (ie, a fluxgate to detect DC leakage current and AC imbalance current)