What exactly is required to calibrate a voltage continuity tester?

[Clink]

I'd always assumed that they didn't but on checking the Operating Instruction for my VCT-GS38, which has bog standard LED indicators, it states it "must be calibrated periodically and checked by our service department at regular intervals .... recommended calibration interval of one year"

 

[Twitchboy]

[FONT=&amp]Approved 2 pole voltage testers (AVT) that indicate voltage in broad bands do not require calibrating. If the AVT incorporates a meter it requires annual calibration, just like any other meter to ensure accuracy[/FONT].

What does testing voltage in broadbands mean? I googled it but I just get a load of stuff about broadband internet. When you say it incorporates a meter do you mean a digital/LCD/Anologue display of some sort as opposed to a row of LED's that indicate voltage?

2 pole AVTs that rely on an illuminated bulb (eg. Drummond and similar types) are required to be GS38 protected by a HRC fuse (500mA) or a current limiting resistor and fuse, these are usually housed in the probes.

Would these HRC fuses be removeable/replaceable? There is no way of telling whether or not my test leads have them inside and if they were in there and blew, how would I replace the fuses as the probes are a totally sealed unit?

2 pole AVTs of the type that have a LED/LCD voltage detector with integral test probe and an interconnected second test probe, have internal GS38 protective impedance and current limiting resistors built into the detector limiting the current (usually <20mA) and energy input to the detector. Therefore they do not require an additional HRC fuse and current limiting resistor in the test leads.

Fascinating stuff, are these resistors in the unit itself rather than in the probes? How would I know if my testers fall into this category? There is nothing on the data sheet that tells me if this is the case.

 

[DPG]

Broad bands as in wide bands, not as in broadband internet! Daz

 

[Twitchboy]

Yeah I figured it wasn't broadband. That's just what came up when I googled broad bands. It's not a term I'm familiar with. I assume it means voltage bands?

 

[snowhead]

I assume it means voltage bands?

Wide voltage bands, with indication it's between the 2, eg, 50 to 110v then 110 to 230v then 230 to 415v

 

[Twitchboy]

Wide voltage bands, with indication it's between the 2, eg, 50 to 110v then 110 to 230v then 230 to 415v

Ah ok, I got you now, thanks.

 

[PRR]

"Digital display" is not the point. I have antique needle-meters with antique calibration stickers.

"Calibrate" to what accuracy? What are you measuring?

For most of my work, I stick it on a 1.5V battery and I stick it in the wall. A fresh carbon battery reads 1.56V. I usually know my wall voltage from several meters and also lamp life/brightness, and if a meter reads close to expected that's good enough for anything I do.

"Continuity" is for trailer lamps. If it beeps when shorted, that's something. There's always a go/no-go threshold, often 100 ohms.... but even in trailer-lamps a 99 ohm "beep" is not good enough to light the lights. So when it really matters you go over to an Ohms range, and check that against a box of cheap resistors (they are all 5% now except when they are 2%).

FWIW, I have un-trimmable meters 30 years old which still read within 2% of what I think they should. Mostly they work "right", they work "odd" because the battery is weak, or they work "way wrong" because something inside is sick.

Yes, meters can drift, and old needle-meters weaken with age. My 1981 MM now reads 12.3V on what I think is a 12.6V car battery. I know that and accept it. Mostly I'm looking for 11V (sick battery) or 15V (sick regulator), not part-Volt differences. And my other meters have shown negigible drift.

If you are trimming electronic amplifiers for 0.234V at TP13, then you need to check near that 0.234V point against a better meter which is occasionally compared to an even better standard.

If you want to know if there is near 230V at a motor, sticking the meter into a familiar wall outlet may be sufficient for your company's purpose. If they want you to check for contacts opening and closing, a beep test may be good enough.

They DO need to watch for field-meters which have been dropped, abused with 8,000V, or left out in the rain to corrode. (However I'd want a weekly quick-test, not annual.)

If you must use the boss's tool, then it is the boss's problem, NOT yours.

 

[Steve_P]

Fluke T100? There's nothing to calibrate on it. You can prove it works with a proving unit (or poking the probes on L & N), takes about 10 seconds. MFT's are what get calibrated.

Use them for basic continuity (nice audible way to check ring continuity quickly), safe isolation and polarity.

 

[Dipzy]

And to be honest that's what the Fluke T100 is designed for ^^^^

 

[penhaifai]

this is old post but I just came across.
Any testing instrument may require to be calibrated by the manufacturer. The instrument manual may have that recommendation as well as the duration recommended by the manufacturer to perform the calibration. Please see attached snapshot from the FLUKE T100 Voltage/Continuity Tester manual.
Any calibration of such usually conducted by the instrument manufacturer or by a well established and certified calibration house. If the company that is using the instrument decided to perform the calibration in house and by their staff then a procedure need to be stablished showing the work instructions, duration and the equipment used in the process as well as what the procedure is covering. i.e. which measurement tools are covered by this procedure.