Hi!
there are many talks about DMM selector grease
BUT few multimeters aren`t greased anyway
Can I use SILICONE oil for what purpose?
Is it safe for high voltage (400V AC)?
Thanx
If you intend to use lubricant on the contacts of the rotary switch, there is a discussion about this on Joe's thread (the multimeter safety thread) and, in his experience (and mine as well) the absolute majority of DMM rotary switches do not use any lubricant, including Flukes, Brymens and Keysights. His experiments showed that the absence of lubricant did not affect the durability of the contacts.
Hi!
there are many talks about DMM selector grease
BUT few multimeters aren`t greased anyway
Can I use SILICONE oil for what purpose?
Is it safe for high voltage (400V AC)?
Thanx
I would advise against it
Many moons ago, a warning came out in ( the then) Telecom Australia, warning against the use of silicone based polishing sprays around exchange relay racks.
Apparently, silicone is a very good insulator, & if it gets between the contacts that should connect, they become open circuit.
Hi!
there are many talks about DMM selector grease
BUT few multimeters aren`t greased anyway
Can I use SILICONE oil for what purpose?
Is it safe for high voltage (400V AC)?
Thanx
I would advise against it
Many moons ago, a warning came out in ( the then) Telecom Australia, warning against the use of silicone based polishing sprays around exchange relay racks.
Apparently, silicone is a very good insulator, & if it gets between the contacts that should connect, they become open circuit.
Oh it's so much worst than that. When it migrates onto any contacts with the slightest potential to arc it gradually becomes silicon carbide and abrades the contact surfaces.
Oils move and spread. You would ruin your multi meter. I also believe selectors resist movement by design. Having something potentially flammable and spread around if there were an arc would not end well.
You forgot to ask or possibly think - why? Purposeless maintenance can lead to failure.
The selector switches use a standard click-stop mechanism comprising a spring and ball bearing; the wipers do not resist movement, and lubricating them will not "loosen" them. As the wipers are held under pressure, they will displace any grease from the contact patch; it's the same as using dielectric grease to coat a plug or terminal: the resistance is not any higher than if air was being displaced.
Contrary to other posts, I have seen grease in DMM selectors. Two thoughts: I can't say for certain if it was applied at the factory, as most of my meters we bought used, but regard it as unlikely that previous owners bothered to add it. Second, it is quite likely that grease was applied to the plastic hub as this is where you need to control friction. With use in varying temperature conditions it is possible for grease to migrate and this may cause it to creep onto the wipers.
One possible reason that some manufacturers' DMMs appear to not contain lubricants is that they use more advanced materials. There are such things as self-lubricating plastics, oil-impregnated bearings, and such that could keep the hub turning without resorting to visible grease; and the wipers can be treated with very thin, basically invisible, lubricant films.
PS: with that being said, I don't think adding silicone oil would help. The wipers and pads are plated with hard gold and (with whatever lubrication the factory used) should take millions of cycles to wear through to base metal. If you cleaned the PCB with alcohol after a battery leak etc then replacing the lubrication could make sense, but just as a preventative I wouldn't do it.
So
I want to protect selector from arc at lamels
Is silicone best isolator than air?
So
I want to protect selector from arc at lamels
Is silicone best isolator than air?
If you think there might be an arc then grease isn't the answer (and probably won't help).
Change the operating procedure, wear protective gear, get a better meter if necessary.
If you intend to use lubricant on the contacts of the rotary switch, there is a discussion about this on Joe's thread (the multimeter safety thread) and, in his experience (and mine as well) the absolute majority of DMM rotary switches do not use any lubricant, including Flukes, Brymens and Keysights. His experiments showed that the absence of lubricant did not affect the durability of the contacts.
If you feel that dropping a grain of sand onto your foot is a good test for justification on if you require steel toed boots, then sure I could understand you feeling that my thread has something to do with safety. For the rest of us, we know that the energy levels are far to low to equate anything I show with safety. Of course I have been saying that for years now.
You are correct about me running across brand new meters with grease. I've seen it used in some meters from the same brand but not across the board
(Not all of their meters have had grease). Fluke for example. Of course we are not talking about the ball detent area but the actual switch contacts. Some of the meters that performed poorly in my transient tests used grease while others that have done very well have had it as well.
So far the meters that performed the best in my 50,000 cycle life test all had dry contacts. That doesn't mean that a meter with lubricated contacts could not hold up just as good. I just don't have any data showing this. For the transient testing, the meters that performed the best have had both. Hard to say.
...
Can You test silicone vs vaseline grease at kilovolts?
...
Can You test silicone vs vaseline grease at kilovolts?
Can you write a test procedure on what you want done and what your goals are? Give it some thought.
Can grease avoid arc at typical lamels space? What voltage for silicone and vaseline?
The only grease i saw in good meter where between the dial and the case, never saw anything on the pcb, even if you use some dieletric insulated grease it may provide a way to arc / spark
Humidity can cause some problems too unless you go for very specialised electrician meters DONT put anything on the traces pads, be sure to clean them properly with no residue left.
I tried on an Fluke 83 because the damn meter was acting strange, my biggest error. It was doing worse after that, had to use very specialised cleaners to remove it, was acting normally after a good clean up.
My other 83 began to do the same thing, a good cleanup restored it fine.
If your stubborn 001 DO IT and see what it will do and dont go over 300v, if it was good in some ways we should see meters with grease in them and as i see it its not the case on any meter i have or had in the past, i have all tear them appart.
You can do your own search ?
Finally i work in rf equipment, if we have anything greassy on the pcb, it fuck all the adjustments to some degree, instabilities ... it does some kind of capacitor effects on the tests points loll etc ... a very good clean up restore stability and effectiveness.
The grease maybe good in DC, but for Ac voltages and rf rejections up to 100khz in most modern meters i would be curious to see some tests.
And finally any greassy stuff may or will attrack dust ... more problems to come ?
MASTECH grease his meters inside
Some meters are greased on the rotary switch, but I have not kept track of it.
I can be seen on some of my tear-down photos, check Mastech MS8268 and AM-Probe AM510 & AM570 (The front photo of the tracks in large version).
I wonder why anyone would consider Vaseline for this application. Then again, what ever happened to the HVAC repair person from down under that suggested WD-40? The key was not to put too much on.
Can grease avoid arc at typical lamels space? What voltage for silicone and vaseline?
Define "grease" and "typical". What about temperature, voltage, humidity..... If you can sort out and document what you would like to see ran and why, I may be able to try something. Just keep in mind I do not play around or even have the ability to do anything with high energy levels. You mention 400VAC and if you are working in CAT III, I assume you are trained and not asking about Vaseline.
Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking.
(and if it stops, how much higher do you need to go to get it to spark again?)
Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking.
(and if it stops, how much higher do you need to go to get it to spark again?)
The problem with using it on wiper contacts as a "safety" measure is that it will be moved around by the wipers and might even get wiped away completely after a while (which is why I don't understand that some meters have it at all).
Again: If the OP is trying to prevent arcs then he seems (to me) to be looking in completely the wrong direction. Prevent arcs by using proper equipment/protocol and not have arcs in the first place.
(and if you're on a budget, buy a fluke 101
)
Oh it's so much worst than that. When it migrates onto any contacts with the slightest potential to arc it gradually becomes silicon carbide and abrades the contact surfaces.
More likely silicon dioxide -- but no less abrasive compared to the soft metal and plating.
I would recommend contact cleaner, or again just nothing at all. Clean it once in a while maybe, that's about it. Maybe more often if you're in a dirty environment (lots of dust), though that's a more general thing, clean the whole board and case say, not just the switch.
If it's a cheap mechanism, not only is it not going to help much, it's not worth spending the ten minutes to open it up and clean it. When it goes flaky, buy a new one and rest easy.
Tim
Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking.
(and if it stops, how much higher do you need to go to get it to spark again?)
I could use that same test setup that I used when I was playing with those 4.7M resistors. Just an uncut board, measure the breakdown, add some room temp Vaseline and see how much higher the breakdown is. The office is cold enough now that at least that stuff wouldn't turn to a liquid.
Not sure what it tells you but would only take a few minutes to run. Want it on video?
https://youtu.be/8Zl2HJ5qo_4
Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking.
(and if it stops, how much higher do you need to go to get it to spark again?)
well
what about transformers in oil tanks?
You want to submerse your meter in oil? I've never thought of that.
what about transformers in oil tanks?
Not the same as a smear of vaseline on a PCB.
Grease is generally bad for electrical contacts. When exposed to an arc it burns, releasing more heat, which can keep the arc burning for longer. Incomplete combustion products such as carbon and tar are also bad. Carbon is conductive and reduces the insulation resistance of the contacts and sticky tar can clog moving parts.
I leaned this the hard way when I let grease used to lubricate a motor bearing get into the brushes, which completely ruined the motor because they weren't replaceable and even if they were, the commutator became badly corroded. I wouldn't expect it to be that bad with a rotary switch, but it certainly won't be good.
I ran a test using Vaseline as requested. I recorded it and will include it as part of my next video. Should be able to post it yet today.
*****
It's on-line.