Question about specification on console of digital capacitor discharger.

[ToddB66]

Greetings !

Can anyone explain what ≈5s means, when stamped on the console of a Digital Capacitor Discharger?
I know those little wavy lines mean "approximately", but what does the 5s mean?
Could the 5s have anything to do with the number of battery cells, or resistors used in the discharger?

Thanks in advance for your help!
ToddB66

[Qiaozhi]

Perhaps it means 5 seconds discharge time.

[ToddB66]

Perhaps it means 5 seconds discharge time.

Thanks Qiaozhi I think you might be on the right track. It's strange, but before I posted my question here, I spent a couple of hours of research out on the internet, using many different combinations of words to find a U-Tube Video or Electronics forum that could answer my question, but to no avail. Then I belatedly thought of Geotech. However, the strange thing is that I had actually found the answer the day before and forgot to save the URL and never could find it again, even after searching through the History section of my Favorites list.... Strange And I don't recall exactly what was said on that URL .... Old age memory!

So, yesterday I contacted Amazon Customer Service and the Agent suggested I send my question to the Seller of the Digital Capacitor Discharger I was interested in buying (It has the following stamped on the face: (100U/400V, ≈5S). I know that the V stands for Volts and after looking up the U on the internet, I learned that it is the European symbol meaning voltage potential. Next, I looked up that little double-wavy-line symbol and it means "approximately", but as I said, I couldn't find the answer to the question in my above post. So, I sent my question to the Amazon Seller and expect a reply within the usual 48 hour waiting period. When I get a reply, if it sounds right, I'll post it here for the benefit of any other members who might be interested.

ToddB66

[moodz]

Thanks Qiaozhi I think you might be on the right track. It's strange, but before I posted my question here, I spent a couple of hours of research out on the internet, using many different combinations of words to find a U-Tube Video or Electronics forum that could answer my question, but to no avail. Then I belatedly thought of Geotech. However, the strange thing is that I had actually found the answer the day before and forgot to save the URL and never could find it again, even after searching through the History section of my Favorites list.... Strange And I don't recall exactly what was said on that URL .... Old age memory!

So, yesterday I contacted Amazon Customer Service and the Agent suggested I send my question to the Seller of the Digital Capacitor Discharger I was interested in buying (It has the following stamped on the face: (100U/400V, ≈5S). I know that the V stands for Volts and after looking up the U on the internet, I learned that it is the European symbol meaning voltage potential. Next, I looked up that little double-wavy-line symbol and it means "approximately", but as I said, I couldn't find the answer to the question in my above post. So, I sent my question to the Amazon Seller and expect a reply within the usual 48 hour waiting period. When I get a reply, if it sounds right, I'll post it here for the benefit of any other members who might be interested.

ToddB66

100 U means 100 microfarad charged to 400 volts .. 5 seconds is chosen as a common timing for this combination as it is not too long to wait for and not too short that the discharge current might exceed the capabilities of your discharger. Why 5 seconds (approx) ?? .... you may well ask ... a capacitor is discharged to approx 99% in 5 time constants .. if the discharger uses a time constant that is appropriate then the the capacitor will be discharged in approx 5 seconds. You dont want to grab the capacitor before it is discharged right. ( even though when I was in the lab many years ago we used to drop a charged cap on the floor and ask the "new guy" to pick it up )

[kt315]

Perhaps it means 5 seconds discharge time.

an useless toy, but probably for university lab there will be good if people often are played with HV capacitors. no practical in my life,
i have special clemms on chinese digital transistor tester for the discharge. sure, i keep an electrolitic > 5 seconds for full discharging.
anyway anyone can check discharged electrolitic on a metal, with maybe a weak spark effect LOL.

[ToddB66]

100 U means 100 microfarad charged to 400 volts .. 5 seconds is chosen as a common timing for this combination as it is not too long to wait for and not too short that the discharge current might exceed the capabilities of your discharger. Why 5 seconds (approx) ?? .... you may well ask ... a capacitor is discharged to approx 99% in 5 time constants .. if the discharger uses a time constant that is appropriate then the the capacitor will be discharged in approx 5 seconds. You dont want to grab the capacitor before it is discharged right. ( even though when I was in the lab many years ago we used to drop a charged cap on the floor and ask the "new guy" to pick it up )

moodz.....Thanks for your reply! To give you some background on myself, I will be age 83, May 31, 2024, and have had a life-long interest in electricity and added electronics just in the last ~10 years. In my early 20's I took a NRI (National Radio Institute), home course in Electricity (Theory of atoms, protons, etc., Small Appliance electric repair, including Clothes Dryers, Motors, heating elements etc., etc..) With that, my father needed help installing lights and outlets in his barn, so my first project was designing and installing an electrical system for that. Subsequently, my wife had started a drapery business in the basement room, and I repaired her irons when needed for a number of years. I also added three electrical circuits.in the garage.

Thirty years later, after raising our family of three boys, finishing their HS and College educations, marrying and leaving home, my wife's business had grown to where it needed more room, so we decided to move and bought a place in the country with a brick ranch style home and a separate 40 ft. x 60 ft. steel building, that served as her drapery room and a wood-work shop for myself. I designed and installed a 40 ft. interior wall complete with electrical outlets to section-off my wife's drapery room at the front of the building, and also a special 60 ft electrical service line (Breaker at the Main and plastic conduit line at the ceiling.) for a Miller stick welder in my wood shop at the rear of the building (We had to buy a high spread-leg ladder for this project. )

I also completed a remodeling job started by the previous owner in the house basement area and installed several electric outlets there. But after ~eight years at that place, my health (Diabetes) forced us to sell to relieve me of all the outside work around our 3-1/2 acres. Now we are retired and have been living in Georgetown, Ohio, in an Apartment complex for the past ~eight years, and I have been amusing myself with small electronic projects. My recall isn't 100% anymore, so I do have to confirm a few electrical facts from time-to-time. Of course, I still have my NRI course, plus the electronics books purchased over the years, for reference. I also go to the internet and electrical forums where I'm registered, to verify electrical/electronic facts. Naturally, I don't always accept every answer I get if it doesn't jive with my previous education or common sense, and this leads me to the following.....

Regarding the symbol U meaning "microfarad charged to 400 volts" that you said, perhaps I need deeper knowledge, but in my post #3 where I said, "I know that the V stands for Volts and after looking up the U on the internet, I took them to mean that the U is the European symbol meaning voltage potential.", I got that information at the following Link, so did I misinterpret something?

My internet query was "what does U stand for in electronics?"
The reply was as follows from Stack exchange forums and note the responder's credentials.
_{Radoslaw J.
PhD., Eng.; R&D Magnetic and Power Electronic Engineer, Project Leader at ABB PL Corporate Research Center}

Both of voltage description "U" and "V" are proper, however it must be mentioned that in European notation "U" describes voltage source while "V" describes rather voltage potential. It means that U = V1 - V1 (voltage is a difference between voltage potentials). I agree that in IEEE and American standards voltage is described by "V" letter.
Very similar situation is with other electric symbols also (e.g. resistors, capacitors, current sources, etc.), where European and American standards are different.

ToddB66

[Carl-NC]

I've never heard that U can mean volts, but if it does then you would not mix U and V together. In this case, it means that a 100uF cap charged to 400V will discharge in about 5 seconds. This implies a constant 8mA of discharge current.
Another possible explanation is that it's made in China, and often the English labeling (and instructions) gets completely butchered, and you have no idea what was intended.

[pito]

European manufacturer


European ohm's law

[moodz]

European manufacturer


European ohm's law

I am well aware that U is taken to mean volts in Euro tech markings ... However when its a chinese manufacturer and the OP said that it was marked 100U 400VOLTS ~~5S then that is chinese for 100 "u" ( ie microfarad ) at 400 volts in approx 5 seconds. If they are using a constant current discharge current internally then you can use this to calculate the discharge time for other caps.

[moodz]

As as a side note on the use of "U" for voltage ...
Germans started calling voltage "U" years ago, probably since that letter was largely unused and so couldn't be confused with anything else. They also came up with etymology: U is for Unterschied, which is German and means "difference"

Whereas in westech we tend to name all the units after dead physicists etc. ( Volta, Ampere etc )

The real question is whether Volta and Ampere could have got a job in an orchestra ... ( were they good conductors ? )