Fluke 80i-410 clamp meter - Page 1
Forum section: electronics / repair

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: September 13, 2015, 06:15:26 am
content: I recently acquired a non-working Fluke 80i-410 DC & AC 400A clamp meter.The output lead had been severed at the strain relief; the battery compartment was badly corroded and the batteries had obviously swollen to such a degree that the case was shattered; and the wires from the PCB to the battery case and the Hall effect sensor were compressed and partly severed in the rear lamination gap.It was a real pig to dismantle as the hinge pin is an interference fit in the hard plastic (phenolic type) body and there was a danger of shattering the whole shebang. I am unsure of the vintage but it must be late 80s-early 90s (It was nice to see waxed lacing cord holding the output lead to the PCB- Ah, memories...)I replaced the output lead and made good the wires, then temporarily soldered a 2X AA battery holder just to check if the meter worked. All seemed OK apart from a very small zero offset. On this meter because of the high range (5A - 400A) there is no user zero adjustment for offset. I wound ten turns of a test lead through the jaws and ran 2A through it- the reading appeared to be about 30% high. There are two multi-turn pots by the output lead which are accessible from the outside. I assume that they are for zero and span adjustment.I spent an afternoon repairing the battery case with a sim card carrier, epoxy and stainless wire (from a chicken feeder!).Before I dismantle it again to draw the schematic- does anyone know of any pitfalls or 'gotchas' in calibrating this type of meter? I intend to wind 100 turns of wire around a former (two plastic lids glued together or a small toy wheel) then pass 4A (AC & DC) through the coil with the jaws clamped around it.Is this a valid process? For what I will use this for realistically it need not be better than 5%, but I would like to get it as good as I can.Regards, BT

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: September 13, 2015, 06:23:42 am
content: Actually the spec is usable max 2A - 600A at DC - 62Hz at +- 5% or 2A.

author: SeanB
author_rank: Super Contributor
timestamp: September 13, 2015, 08:27:38 am
content: Will work, and is probably used as the calibration in any case, as otherwise you need to make a transformer with a single turn secondary and drive it to that current in a single shorted loop. You are just removing the transformer shorted loop and core.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 13, 2015, 09:21:48 am
content: That is exactly how I calibrated my high current Fluke probes and it worked very well.

author: SeanB
author_rank: Super Contributor
timestamp: September 13, 2015, 09:51:12 am
content: I am running a wattmeter using a similar method, using a current transformer with a 10 turn primary and a 1 turn secondary, so as to increase resolution. Primary up to 6A and secondary 60A, with the whole lot on the one phase for the voltage coil.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: September 14, 2015, 04:40:26 am
content: Thanks all, I'll get winding today !There is nothing but an LM10 op amp and a signal transistor in the Fluke so I assume that someone had an uneducated twiddle with a trim tool when the device stopped working due to the wires being pinched/severed.It isn't a great mechanical design considering that it is a Fluke, but it was free to me.Regards, BT

author: ModemHead
author_rank: Frequent Contributor
timestamp: September 14, 2015, 11:58:02 am
content: The Fluke 5500A Current Coil might provide ideas for your setup...https://www.google.com/search?q=fluke+5500a+coil&tbm=isch

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: September 14, 2015, 12:38:08 pm
content: Thanks Mr ModemHead,I had spotted the Fluke calibrator, and a line drawing of the coil which looks like a torus but I think it was just for clarity.I found 17 metres of varnished copper wire on an old coil and wound an experimental 65 turns on a former. I tested it with 1A from a psu and borrowed a UT210E which read 65A dead. I zeroed the Fluke and set it for 65A and all seems well.I have a couple of speaker Xover coils in the parts bin which seem to be 100 turns-ish. With 0.5A through, the Uni-T read 51A (100A max for the meter), and with 1A the Fluke read 98A. I will wind a 200 turn or more tomorrow and fine tune the Fluke.Thanks again, BT

author: ModemHead
author_rank: Frequent Contributor
timestamp: September 14, 2015, 05:40:52 pm
content: Sounds like you mightwind upwith a successful repair.From appearances of the Fluke unit, I can't help but think one could possibly turn a Slinky toy into a calibration jig...

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: September 15, 2015, 02:31:24 am
content: C'mon Mr MH - this is a serious forum. Everybody knows that a Slinky isn't insulated... now where is my transformer varnish...

author: ModemHead
author_rank: Frequent Contributor
timestamp: September 15, 2015, 12:00:23 pm
content: Little duct tape'll fix that right up. -Red Green