Well done - although I have to say that that is more than I would personally pay, or would feel that I needed to pay, for a secondhand MFT - particularly since, as I pointed out before, you could buy a new MFT for that sort of price. I hope you enjoy your purchase and have fun with it!
I think that one would have cost around £1,000 new. However, as I said, before, you could have bought other MFTs for the sort of price you paid - e.g. (I think I gave this example before) a Fluke 1662 for around £550 (plus VAT).
That's what matters. I hope you enjoy it, and that it gives you a good few years of service.
... and I hope it continues to serve you for a good few more years.
I can understand that.
I've only ever used the 2-wire no trip function a couple of times, but I can only assume it uses ~20mA for the test. This obviously means it takes longer and is, to a certain degree, less accurate than a hi-current test.
I suppose that would be the obvious answer - I suppose one could put constant current circuitry between L and E and measure the consequential change in L-E pd, but that would be pretty tiny (about 7mV with 20mA and and EFLI of 0.35Ω).
In view of my above comment, I can well believe that it would be less accurate, but it's not 'obvious' to me why it takes longer (does it perhaps make multiple measurements in an attempt to improve accuracy?).
My Fluke 1652 takes a second or two. As for the different readings you mention, strictly speaking, if you only have two (different) results, you can't be certain as to which one is closer to the truth (although, as I presume you're doing, one can make an educated guess!).
Maybe it's just a foible of the 1552. It takes a fair while to do RCD testing too. You can hear relays clicking away as it charges and discharges capacitors and whatever other fancy stuff it's doing under there
Ramp testing obviously does take a little time, because it has to undertake multiple tests and, as you say, get its act together in between each one.
Ramp testing or auto RCD testing?
