What would this capacitor be used for??

[fecmech]

I stopped at a yard sale today and they had 5 of these in a box. I asked the lady what the capacitors were for and she said I was one up on her because she didn't even know what they were. My curiosity was piqued so I bought one for a dollar and bring it before the all knowing cast boolit board to find out it's use. Where would a fellow use this thing??

[Ickisrulz]

A time machine or teleporter I would think.

[Ballistics in Scotland]

A starter for a brushless electric motor, perhaps? The voltage quoted is probably a maximum, rather than intended.

Jules Verne, in his "20,000 Leagues Under the Sea" of 1869, portrayed not only a fast and manoeuvrable electric submarine, but an underwater rifle with a Leyden cell to electrocute the quarry. Nice work for the time, but I doubt if any Leyden cell could deliver a voltage you could feel. As rifling twist must be proportional to the square root of the medium through which the bullet passes, it would have had to be thirty times faster than in air.

Homeland Security, though, have been working on a sort of capacitor-powered taser to be shot from a shotgun, which is said to be capable of immobilizing someone for 20 seconds, at 20 metres. I don't know whether they have got it reliably up to specification yet.

[MUSTANG]

Given the size; I would guess for a large electric motor (water well perhaps); or in a RADAR or high wattage HF Transmitter.

[garym1a2]

You are most likly correct. Or it could be a military UPS. Since it has a Military part number no telling.

http://www.armyproperty.com/product/52414/12-712417-00/



A starter for a brushless electric motor, perhaps? The voltage quoted is probably a maximum, rather than intended.

Jules Verne, in his "20,000 Leagues Under the Sea" of 1869, portrayed not only a fast and manoeuvrable electric submarine, but an underwater rifle with a Leyden cell to electrocute the quarry. Nice work for the time, but I doubt if any Leyden cell could deliver a voltage you could feel. As rifling twist must be proportional to the square root of the medium through which the bullet passes, it would have had to be thirty times faster than in air.

Homeland Security, though, have been working on a sort of capacitor-powered taser to be shot from a shotgun, which is said to be capable of immobilizing someone for 20 seconds, at 20 metres. I don't know whether they have got it reliably up to specification yet.

[texassako]

For a dollar each, I would have bought all 5 and made a coil gun.

[sdcitizen]

All 5 would also make a dandy phase shift motor starter for a rotary phase converter.

[quietmike]

The corona treaters at my work, a print shop, use 12 capacitors that are larger than that, 2 farads each IIRC.

[fatnhappy]

They're clearly flux capacitor parts.




Since we're guessing here, I'll SWAG they're for HVAC, possibly a chiller. Did I win?

[runfiverun]

I'd have to charge one up and hand it to my buddy :lol:
then I'd know if it's good for something or not.

[blademasterii]

My first thought too. It would be good for hooking to a doorknob as a first line of defense home security.

[berksglh]

DC buss capacitor for some form of AC motor variable frequency drive (VFD), or inverter welder. Seems about right size, voltage and value. Most of the older inverter welders used lower voltage bus caps. The newer stuff utilizes a boost circuit and runs bus voltage as high as 950vdc. I use to be an authorized Miller and Lincoln welder repair mechanic. Have a pile of similar at home as spares for an XMT304.

Any form of inverter could utilize such a cap for bus voltage.

[fecmech]

I'd have to charge one up and hand it to my buddy :lol:
then I'd know if it's good for something or not.
We did that in the electrical class when I went to A&P school, you learned to be careful picking up a capacitor.
Thanks to all who took the time to reply, I appreciate your input. Brassmagnet PM'd me and asked if the cap had screw terminals and a button as those were used in charging systems for navigational aids. It appears that is what I have. Again, thanks to all.

[6bg6ga]

Don't charge it up and then shock yourself because it could be the last shock you would ever get. A couple of them in a power supply for a tube hi fi amp would be dandy as it would yeald a 900 VDC rating at half the capacitor rating when wired in series . So 900VDC/900MFD

[fecmech]

Don't charge it up and then shock yourself because it could be the last shock you would ever get.
No worry there. My first thought when I saw these was they could possibly kill you.

[BwBrown]

Is it possible that the original owner was into audiophile sound. We use such caps in the high voltage power supplies of tube (some would say valve) audio amplifiers.
Long story short, increased capacitance results in stronger bass response.
Purists will claim to hear the difference in different types: plastic, mica, oil in paper.
And yes, they can put you in a world of hurt at the speed of light.

[turmech]

Start capacitor for a central A/C or heat pump compressor.

[edctexas]

This could be for a ham radio amplifier power supply. I built one using caps just like that four in series with a high value resistor across each to be sure the voltage is divided equally. The VFD for a motor is a good possibility.

Ed C

[bangerjim]

Start capacitor for a central A/C or heat pump compressor.

You do not use DC caps on AC motors. If a starter cap, it will be rated in MFD @ xxx VAC not VDC.

Probably mil stuff. Most 400+ VDC filter circuits do NOT use that high an MFD. Most are 200MFD or so.

VFD's are 3 phase AC power normally 220/440 VAC.....NOT DC. VFD is short for Variable Frequency Drive. Frequency varies to adjust speed of a 3 phase AC motor.


I have 2 VSD's (Variable Speed Drive) that are 90 VDC motors and use much smaller caps than that huge MFD rating.


Should have bought all of them! Fun to play around with at that high voltage and MFD!! You can scare the CARP out of someone charging it and then shorting it out near them!! B_A_N_G!!!!!!

I was a very bad child!

banger

[Elkins45]

1800 microfarads is a darned big capacitor. Be careful with thing---they may have come from a portable electric chair.

[ProfGAB101]

You do not use DC caps on AC motors. If a starter cap, it will be rated in MFD @ xxx VAC not VDC.

Probably mil stuff. Most 400+ VDC filter circuits do NOT use that high an MFD. Most are 200MFD or so.

VFD's are 3 phase AC power normally 220/440 VAC.....NOT DC. VFD is short for Variable Frequency Drive. Frequency varies to adjust speed of a 3 phase AC motor.


I have 2 VSD's (Variable Speed Drive) that are 90 VDC motors and use much smaller caps than that huge MFD rating.


Should have bought all of them! Fun to play around with at that high voltage and MFD!! You can scare the CARP out of someone charging it and then shorting it out near them!! B_A_N_G!!!!!!

I was a very bad child!

banger

Note a VFD works by taking in AC power and running it through diode rectifiers to make DC power which is stored in large capacitors, then a type of transistor (mosfet, fet, or IGBT) switches pulses from those caps to recreate AC power at the requested frequency. A really good VFD can provide output from 2Hz to 1600Hz though a 6Hz to 400Hz range is more common. Cheap units are often limited to like 20Hz to 120Hz. A common trick is to run AC through a bridge rectifier and feed that into the power inputs on a VFD to reduce the load (read that as internal heat buildup) on the internal diodes. (don't try this at home unless you understand how and why this works!)

[fecmech]

If anyone wants this one I'd be happy to send it to you, I just bought it out of curiosity.

[dragon813gt]

Start capacitor for a central A/C or heat pump compressor.

It's not AC and it doesn't have a range. Start capacitors always have a range and bleed resistor soldered across the terminals.

[garym1a2]

Since the cap has a military part number on it you are probally right.
Given the date code on the cap it was probally sold off as surplus.[
QUOTE=bangerjim;3265622]You do not use DC caps on AC motors. If a starter cap, it will be rated in MFD @ xxx VAC not VDC.

Probably mil stuff. Most 400+ VDC filter circuits do NOT use that high an MFD. Most are 200MFD or so.

VFD's are 3 phase AC power normally 220/440 VAC.....NOT DC. VFD is short for Variable Frequency Drive. Frequency varies to adjust speed of a 3 phase AC motor.


I have 2 VSD's (Variable Speed Drive) that are 90 VDC motors and use much smaller caps than that huge MFD rating.


Should have bought all of them! Fun to play around with at that high voltage and MFD!! You can scare the CARP out of someone charging it and then shorting it out near them!! B_A_N_G!!!!!!

I was a very bad child!

banger[/QUOTE]

[jonp]

They're clearly flux capacitor parts.




Since we're guessing here, I'll SWAG they're for HVAC, possibly a chiller. Did I win?
^^^ yup

[MaryB]

If you can get the other 4 I could use them.. be perfect for the ham amplifier I am building.

They are a power supply filter capacitor and pretty common. Not cheap brand new but they do dry out over time so it is a **** shoot if it is any good still.


If anyone wants this one I'd be happy to send it to you, I just bought it out of curiosity.

[Cmm_3940]

Is it possible that the original owner was into audiophile sound. We use such caps in the high voltage power supplies of tube (some would say valve) audio amplifiers.
Long story short, increased capacitance results in stronger bass response.
Purists will claim to hear the difference in different types: plastic, mica, oil in paper.
And yes, they can put you in a world of hurt at the speed of light.

These are also commonly used in high end car audio applications. Higher inrush current capacity than the alternator/battery can provide to feed the big amps that produce the annoying thumpa-thumpa-boom you hear whenever one drives by. They also cost a lot more than a buck.

[bstone5]

The power supply for large car stereo use large capacitors to supply the amplifier.
My son installed big amps in his truck when he was a teenager he always had a big capacitor at the battery where the power went to the amplifier.

[MaryB]

Those are 1 farad or larger low voltage capacitors, typically 20 volt or so.

[6bg6ga]

I will agree with Mary.I may have 4 larger caps that are unused somewhere in the garage

[fecmech]

Mary--I'll keep an eye out for that garage sale over the next week. It's raining today but if the lady still has them I'll pick up the rest for you if you like.

[TheDoctor]

They can also be used in a cap bank for x ray machines.

[MaryB]

Sweet! I am building a small amplifier they would be perfect for if still good.

[David2011]

I've seen some pretty big similar capacitors in commercial photography studio strobe power packs. I used to use a Graflex strobe that had a pair of +/- 500 mfd caps in it powered by a pair of 225 V batteries and that was a portable strobe.

David

[MaryB]

They are used for a lot of things, all power related where they either provide a quick power surge(flash) or they smooth out the A/C ripple from the power supply rectifiers. Dangerous to handle if fully charged at rated voltage, it could deliver enough current to stop your heart! And it WILL leave a burn on the skin! Accidentally laid the back of my hand over one that I couldn't see in a power supply. I discharged the visible ones but that one was hidden.

[TheDoctor]

Only takes 2 milliamp to stop your heart, if there's enough voltage to push it.

[MaryB]

Power supply for one of my amplifiers is 2,400 volts at 1 amp... yeah it will do serious bodily harm!

[BwBrown]

Sounds like edctexas and MaryB are amateur radio operators.
How many more of us are there in our ranks?
Bob;
kc3cgq

[MaryB]

W0AAT and several!