My suggestion/question was .... If a device (i.e. Type B) is designed to be trip with 'smooth' DC residual currents, it is presumably also designed to be able to function satisfactorily (without saturation) in the presence of high L and N DC currents. However, since A and AC ones are not designed to trip with such DC currents, it would not be surprising (at least, not to me) if they were also not designed to work (i.e. not to saturate) in the presence of L & N DC currents.
That is, indeed, very likely - but it does not, in itself, explain why the treatment appears to trip one RCBO but not the other two, nor why the trips appear not to occur until the treadmill has been running for some time. As has been discussed, difference between the characteristics/performances of the different protective devices might possibly account for this.
5 uses of 'not' in one sentence has to be approaching a record!
I refer the honourable gentleman to post #69...
I read this whole thread before replying, obviously I didn't do a very good job of it!
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