Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

[mansaxel]

I've seen very high value (100A plus) fuses filled with sand (or something). I assumed it was there for quenching. When it blows you want it to stop conducting, not to continue as an arc.

Diazed fuses (Siemens invention from the early 1900s) as used in Sweden and Germany (Among many other places!)
are sand filled, down to the household sizes of 6,10,16 A.



Most domestic fuse panels in Sweden have D II fuses.



These days, they're being installed only in select places. Most domestic uses have replaced them with DIN rail mounted MCBen.

[AVGresponding]

All modern HRC fuses have some sort of filler for arc quenching. It shouldn't be sand: https://www.electricaltechnology.org/20 ... types.html

[Zenith]

Some of the old UK power circuit fuses had the wire running through an asbestos tube. I've also seen asbestos used around the fuse in some domestic radios.

[Robert]

The granualar material in high rupture current fuses isn't so much for arc quenching (stopping conduction) as energy absortion to stop the fuse physically exploding. It presents a large surface area to the hot expanding gases cooling them and reducing internal pressures.

[AVGresponding]

It quenches the arc by removing heat, and also there's a chemical reaction making the metal-filler fused product highly resistive.

[Zenith]

All modern HRC fuses have some sort of filler for arc quenching. It shouldn't be sand: https://www.electricaltechnology.org/20 ... types.html

They mention a number of fillers in articles about HRC fuses; silica (purified sand), marble (calcium carbonate), Plaster of Paris (calcium sulphate). The wire is made of silver (which must be for good reason) and they talk about the metal vapour reacting with the filler to create an insulating compound. No doubt the other effects mentioned are also taking place.

There must have been a lot of R&D done on getting these right.

[mnementh]

trace fuse 2.jpg

trace fuse 1.jpg

Meanwhile, on the other end of the spectrum...

mnem

[25 CPS]

I guess it's hard to find good technicians whether it's a paid or volunteer environment.

Somebody needs to train them.
If that isn't possible then have supervision.
If that isn't possible (e.g. voluntary organisation) then at least have three people working alongside each other, so that there is a better chance someone will stay "wait a minute". ("alongside" != at other end of cable).

Over here we used to have apprenticeships, where companies trained school leavers before they employed them. That was possible when it was less likely people would be "stolen" by another company and/or move to a different town.

Apprenticeships exist here too, mainly in the skilled trades but do appear elsewhere too, and work placements for college and university students are common.

The guy who destroyed my clamp meter is a full blown EE with decades of experience, both in industry and at that railway museum. This is why I keep harping on the carelessness.

As for the others, you can't train common sense, work ethic, or that sort of thing. Eventually people have to stand on their own two feet but not everyone can to the same extent but, far worse, are the malicious ones that slack off or deliberately damage things. I haven't encountered the latter in volunteer situations much though. The lazy factor tends to rule out volunteer work.

Anyways, I ordered a replacement U1213A yesterday. Hopefully it checks out alright when it arrives.

[Zenith]

The guy who destroyed my clamp meter is a full blown EE with decades of experience, both in industry and at that railway museum. This is why I keep harping on the carelessness.

Some people seem accident prone, others just can't treat things properly. I had a friend who couldn't have a camera for more than about a year, because he dropped them or wrecked them some other way. They weren't cheap ones, they were Nikon etc. He got through half a dozen and he didn't use them that much. It never seemed to dawn that they were expensive things and needed reasonable care. I lent a corded hedge trimmer to another friend. He managed to cut through the cable. Some people are notorious for abusing tools, even expensive ones. It doesn't seem to have that much to do with intelligence or training.

I had a builder to do some work on the chimney. He hired a scaffold tower. I asked him why he hired them, since it was a thing he'd use all the time. He said if you hired one, it would be complete with no missing or damaged bits. If he bought one, people would ask to borrow it and it was hard to refuse, and it would often come back with parts bent or lost. It was too much hassle to buy one. Tool hire companies were geared up to deal with scaffolding towers returned with lost or broken parts.

[tggzzz]

As for the others, you can't train common sense, work ethic, or that sort of thing. Eventually people have to stand on their own two feet but not everyone can to the same extent but, far worse, are the malicious ones that slack off or deliberately damage things.

Arguably even worse are the well-meaning people that know just enough to be ingeniously dangerous.

In my first job I encountered such a person, who was universally known as "bigfoot". Glider (and no doubt other) instructors are especially wary of "Bloggs" who are approaching solo standard, since they get into situations that gently become subtly dangerous. When the instructors are being tested (annually), the testers mimic such Bloggs in order to see the instructor does take control.

[Robert]

Apprenticeships:
These are still offered by my employer and have been for over 100 years. The current chief engineer is an ex apprentice and has been with the company for 40 years....

Scaffold towers.
Renting these also means that they have an up to date inspection tag which removes another administrative chore.

[MED6753]

This is not unheard of in mid-April but rare and most unwelcome. Sloppy mess and today will continue. Tomorrow the temperature will soar and melt. The latest I have ever seen snow here was first week in May.

[Zenith]

I have a picture somewhere of daffodils in full flower, weighed down by about 3 inches of snow. I recall it was taken in early April about 8 years back. Very unusual for the south west of England, but it does happen from time to time.

For the past three weeks the weather has been unusually warm and sunny, with almost no rain.

[25 CPS]

Today's pickup, and I apologize for the mediocre photo that was all I had a chance to get before hopping on the train to a midnight shift, was a Simpson 657 milliohmmeter Add-a-Tester for the 260 multimeters:



The two cables coming out the right side are four conductor Kelvin arrangement that one would expect for low ohms measurements.

I know I posted pictures quite a while ago of the 661 DC ammeter:



I don't think I ever posted pictures of the other Add-a-Tester adapters I've picked up so here are a couple of grab shots I took the other day when I was arranging to buy the 657 of the transistor tester and temperature tester:





It's hard to see but the temperature tester is still in its original box with original paperwork.

Simpson made nine of these adapters and I now have four of them which kind of kicked off an itch to finish out the collection.

[Cubdriver]

Interesting - that's the first I've ever heard or seen of them. Fortunately, I don't have a 260 - used Triplett 630s in HS and so developed an affinity to that breed. Hunted one down years ago; it's buried around here somewhere. Good luck in chasing down the rest of them - that'll be a cool collection of measuring instruments!

-Pat

[MED6753]

I never heard of those Simpson adapters either. Very interesting.

[25 CPS]

Interesting - that's the first I've ever heard or seen of them. Fortunately, I don't have a 260 - used Triplett 630s in HS and so developed an affinity to that breed. Hunted one down years ago; it's buried around here somewhere. Good luck in chasing down the rest of them - that'll be a cool collection of measuring instruments!

-Pat

It's interesting how so many people lean one of three ways on analog VOM meters based on what their early experiences are. The El Paso Tube Amps guy on YouTube is another serious Triplett 630 user but W2AEW on YouTube is a serious Simpson 260 user, for examples of each, and then a lot of British and British Commonwealth people are frequently serious AVO users.

One of my co-workers went to college in London, Ont. in the late 1980s and the Simpson 260 apparently had the reputation as the meter to buy if you were a student that was serious. That reputation was probably established by the fact that Bach-Simpson had made them locally in-town for decades.

For me, personally, there wasn't any early in life experience that set me one way or another on this. My parents always bought the cheapest, nastiest Radio Shack or Canadian Tire meters and battery testers whenever we needed something at home and I didn't take electronics in high school. I was more interested in computers back then and someone who did take the electronics class told me they weren't allowed to use capacitor with the stated reason being that the safety hazard associated with them exploding was too great. This immediately caused the electronics course to lose credibility with me so it wasn't too hard to talk me out of signing up for that one with the limited number of chose your own elective courses slots on the timetable.

I have a few Simpsons, Tripletts, and AVOs, and having examples from all three manufacturers, it's the Simpson 635 HV that I reach for first whenever I need an old style VOM. I ended up with that one totally by accident thinking I was getting a 260 and it's become my favourite VOM, and I can't quite put my finger on why but it's a preference that's emerged only in middle age. I'd like to get a second good one sometime and I've been keeping an eye on some sales listings towards that end.

[Cubdriver]

The 635HV is another I'd never heard of - just looked it up - wow, 6 kV! Are the HV ranges just additional voltage dividers that you plug into and select a lower voltage range using the selector knob, or? (It's not obvious from looking at the pics I found online.)

I do have a Simpson 269, but need to get the 22.5 V battery and some pin plug test leads to really wring it out. I did give it a decent cleaning a few years back, but haven't gone further thus far.



Additional pics of the cleanup are at: https://pmanning.smugmug.com/Electronic ... on-269-VOM

-Pat

[tautech]

The 635HV is another I'd never heard of - just looked it up - wow, 6 kV! Are the HV ranges just additional voltage dividers that you plug into and select a lower voltage range using the selector knob, or? (It's not obvious from looking at the pics I found online.)

I do have a Simpson 269, but need to get the 22.5 V battery and some pin plug test leads to really wring it out. I did give it a decent cleaning a few years back, but haven't gone further thus far.
-Pat

Last I needed a 15V one for a VOM I found them ridiculously expensive so made my own from a stack of LR44 button cells held together with heatshrink and a short length of brass tube to make up the length shortfall.

Or are the 22.5V a different arrangement ?
2x 12V remote batteries and a diode or 2 might work also.

[Cubdriver]

Last I needed a 15V one for a VOM I found them ridiculously expensive so made my own from a stack of LR44 button cells held together with heatshrink and a short length of brass tube to make up the length shortfall.

Or are the 22.5V a different arrangement ?
2x 12V remote batteries and a diode or 2 might work also.

I see both alkaline replacements and one some guy home brewed from what appear to be lithium button cells and shrink tubing on the Bay of Evil. If I scare up some appropriate test leads (and remember where I stashed the damned meter!!), I'll cobble one together myself, or perhaps order one from the wallet depletion site - they're about $25.

-Pat