Tech / Special Interest → Electronics > User manual for OTC 3392 multimeter

User manual for OTC 3392 multimeter

My search skills have failed me.

Does anyone have, or can anyone find a user's manual for this DVOM?
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The talented hawk speaks French.

Looking at some pictures on eBay it doesn't seem too complicated.
What exactly do you want to know?

I was hoping to find something that states its category/voltage rating.

I need to use a CATIII 600V meter, and if I can show that this one fits the bill, I won't have to buy a new one.

It was decent $ back in the day, and still works fine.

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The talented hawk speaks French.

In order to be classified as a 600V Cat III meter it needs to be certified to withstand a 6kV impulse. The meter itself (not just the user manual) should be marked with the rating and the specification that was used.
This may look like "EN61010-1 Cat II 600V" as it is molded into the case of an inexpensive multimeter I bought many years ago. Imported products may show an IEC specification while products made in or for the US are more likely to show UL61010B (the meaning of the different categories is the same in either case).
If there is no such marking on the meter itself it most likely was never certified for compliance with any of the safety specifications.
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Meter states 750 V AC, 1000V DC max.

No certifications printed on the meter itself.

Thanks all.

I guess I will be shopping for a meter.

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The talented hawk speaks French.

I don't think that the specs themselves require re-certification since they don't even require each individual unit to be tested (product safety certification is different from calibration for accuracy). The only deadline that I'm aware off is that manufacturers have up to 3 years to re-certify a previously certified product for compliance with a newer revision of the specification (beyond that deadline the manufacturer cannot continue to mark a product as compliant with the previous revision of the specification).
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Thanks for the shootout link.
It helps me to get a sense for what is out there.
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The talented hawk speaks French.

Are Flukes still considered a good meter for safety? Some tended not to have all the flashy features or claim the most accuracy but for certain uses for higher voltage and high amps they where consider safer. Not as likely to blow up in your hand unless you really screwed up.
I have an older one I pull out when using for those type of uses.

Thanks for the table.
It is nice to see CAT III and 600V in context.

One thing though, what is the idea of "30 Ohm Source"?
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The talented hawk speaks French.

You'll notice as the Cat rating goes up the source impedance goes down. The lower the source impedance the more energy is delivered to the load. The over current protection must be rated to successfully interrupt this fault current.

Interesting Fluke video pertaining to electrical safety.
»download.fluke.com/video-safety/···deo.html

/tom

A power supply with 2500V nominal voltage and a 30 Ohm internal resistance will be able to provide a short-circuit current a little more then 80A. The lower the resistance the higher the current can be. The 8000V from a power source with only 2 Ohm internal resistance can deliver a short-circuit current of 4000A ! That is the kind of power where you should say "forget about personal protection devices, I'll be in the room next door"

Those resistance values are a reasonable approximation of the type of power sources you may encounter in the different measurement categories with Cat I being low-voltage signalling and Cat IV being the utility power grid.
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Thanks guys. That makes sense.

I am not used to thinking in terms of the resistance of a power source.
I do understand if I am thinking in terms of how much energy can potentially be delivered by different power sources though.

In that context, the HV battery of a hybrid vehicle would have a relatively low internal resistance.
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The talented hawk speaks French.

Don't underestimate the good old 12V car battery. It has some pretty impressive specs, including a very low internal resistance (that is what allows it to produce all those Cold Cranking Amps).
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As leibold posted as the source impedance goes down the available short circuit current goes up. Automobile lead acid batteries, as opposed to deep cycle batteries, are designed to produce a lot of current for a short period to crank the starter. Not as much as the Hybrid vehicle battery pack but enough to be treated with respect.

The cold cranking amps (CCA) spec defines how much current the battery is able to deliver at 32F while maintaining an output voltage of at least 7.2 volts. If you short the battery terminals together current will be much higher.

From a safety perspective high current presents a thermal and explosion hazard as current flow generates heat.

High voltage presents a shock hazard, it does not take a lot of voltage to cause 5ma to flow through your heart causing ventricular fibrillation.

The other safety issue with high voltage arc generation. Once an arc is struck it creates a low resistance plasma that allows current to continue flowing. This is why the fuse in a Cat rated multimeter is so large. They use construction techniques that helps extinguish the arc. If that fails current continues to flow and the meter burns up. Worse if there is enough voltage and or current available you have an Arc Flash event. Not a pleasant experience and often fatal.

The Fluke video I posted talks about arc flash.

/tom

So have you bought you shiny new meter yet? Which one did you choose?

/tom

No, not yet.
I am going to work through some expenses first...
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Mine isnt that old. But not new either. I thought when I bought it that they tended to be the safest or one of the safest meters around. It says it is cat rated. Plus they bragged about being better even than that in their safety videos. Was still made in US at the time. Production then was moving overseas. Do not know or kept up if all production moved overseas. Mine say 1000 cat 3 and 600 cat 4. Made in usa

I found the operators manual for my 3392 and it does not have any Cat certifications in the specifications. If you still need any info from the manual I can scan it for you.

Thanks a ton for looking.
That is all the info I was looking for.
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I realized that this meter I have:
Sanwa CD721

»radio63.narod.ru/page/sanwa/cd721.htm

Is Cat III 600V.

It was only about $100.00, so I had not thought it might be CATIII, but it is. It doesn't have all the features of the 3392, but it is newer and rated appropriately.
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