Author Topic: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla  (Read 4023 times)
ggillis
Member
***
Offline

Gender: Male
View Posts
View Gallery

AEL 175W NEMA


7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « on: March 24, 2017, 01:55:04 PM » Author: ggillis
Hey everybody, just looking for opinions on using a 7.5uF cap. instead of a 7uF cap on an advance CWA mercury vapor ballast?
Logged

Red Seal Electrician

Click on the link below to view my gallery:

http://www.lighting-gallery.net/gallery/index.php?cat=11790

Lodge
Member
*****
Offline

View Posts
View Gallery

18W Goldeye / 52W R&C LED front door lighting


Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #1 on: March 24, 2017, 06:58:14 PM » Author: Lodge
Your using it to change the power factor, expect a change to the current crest factor, but not by much with only a 0.5 uf change, have you measured it to see which way the tolerance is on the cap some can have very large swings + or - for all intense purposes it might be close enough...   
Logged
Foxtronix
Member
*****
Offline

Gender: Male
View Posts
View Gallery

Formerly "TiCoune66". Also known here as Vince.


GoL UCs4tSgJSCoCIMGThBuaePhA
WWW
Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #2 on: March 25, 2017, 12:30:46 AM » Author: Foxtronix
On constant wattage ballasts the capacitor also provides some current limitation to the lamp. A higher value capacitor will allow more current to flow in the lamp, but also in the ballast, making it run hotter. At the extreme the ballast burns to a crisp, as I've seen in a high bay fixture once. Though in that case the ballast (a 347V CWA) originally used a 18.5uF, while I found a 24uF inside the fixture next to the original cap that was left disconnected.

Though in your case the difference isn't that big, and certainly not enough to cause damage in the short term. To be extra sure you can measure the current consumption and see if it matches the spec (if there's one).
Logged

Lightingguy1994
Administrator
Member
*****
Offline

View Posts
View Gallery

Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #3 on: March 27, 2017, 02:39:44 PM » Author: Lightingguy1994
0.5 shouldn't make much difference. When caps age I'm sure they vary in rating over time slightly
Logged
Ash
Member
*****
Offline

View Posts
View Gallery


Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #4 on: March 28, 2017, 07:12:55 PM » Author: Ash
Or not so slightly. From what i seen F96T12 HO Rapid Start ballasts for 230V/50Hz stop working when the capacitor is at or around 1/2 its rated value
Logged
Medved
Member
*****
Offline

Gender: Male
View Posts
View Gallery

Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #5 on: March 30, 2017, 07:45:19 AM » Author: Medved
With CWA the current regulation mechanism is capable to "swallow" quite large tolerance into its regulation range (7uF vs 7.5uF is quite large tolerance for a current definition component), so very likely it will work.
Logged

No more selfballasted c***

randacnam7321
Member
***
Offline

View Posts
View Gallery

Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #6 on: April 30, 2017, 08:36:27 PM » Author: randacnam7321
The 500nF difference is also commonly within the manufacturing tolerance range.
Logged

Old school FTW!

Lodge
Member
*****
Offline

View Posts
View Gallery

18W Goldeye / 52W R&C LED front door lighting


Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #7 on: May 29, 2017, 05:02:09 PM » Author: Lodge
Any luck with it ggillis, did it work or did you get the right cap ?
Logged
delaware74b
Member
**
Offline

View Posts
View Gallery

Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #8 on: June 04, 2017, 08:29:17 AM » Author: delaware74b
IMO, I wouldn't use the 7.5uF on that ballast (even with MV). Is the capacitor in series of that lamp?

The capacitors are spec'd at +/- 3% on CWA ballasts, so the acceptable range is 6.79 to 7.21uF.
Typically, capacitance decreases as the capacitor ages.

I work on CWA 1KW MH pole lights on a regular basis and capacitors are critical to proper light output
and lamp life. These fixtures use 24uF caps and they get replaced when they read 22 or less.
Logged
funkybulb
Member
*****
Offline

Gender: Male
View Posts
View Gallery


Re: 7.5uF capacitor in place of a 7uF capacitor on a 50 watt CWA mercury vapor balla « Reply #9 on: June 04, 2017, 09:30:07 AM » Author: funkybulb
I would use two caps in parralel ( many times lighting caps tend be out of my price range) 3 uF and 4 uF
Caps together.  Amrad makes good caps and they
Give 5 year warrenty as soon u purchase them

http://m.ebay.com/itm/4-MFD-x-370-440-VAC-Oval-Run-Capacitor-AmRad-USA2028-Made-in-the-USA-/181736127547?hash=item2a50513c3b%3Ag%3AVXkAAOSwBLlVSOLB&_trkparms=pageci%253A3b48be4f-4925-11e7-b029-74dbd1801ace%257Cparentrq%253A732daa0815c0ab6af75f39a0ffff7617%257Ciid%253A16

Also this together

http://m.ebay.com/itm/OEM-Amrad-Run-Capacitor-3-3-0-uf-MFD-370-440-Volt-VA2000-37-305-Made-in-USA-/371622240482?hash=item56866960e2%3Ag%3Alb8AAOSw2x1XMMo9&_trkparms=pageci%253A023f9eb2-4929-11e7-87ee-74dbd18013e0%257Cparentrq%253A73466b2315c0aca4b4bab184fffedbcb%257Ciid%253A20

I never had any problem runing motor caps
Also u can call Amrad up they can make any size cap type of cap u need
Logged

No LED gadgets, spins too slowly.  Gotta  love preheat and MV. let the lights keep my meter spinning.

Print 
© 2005-2024 Lighting-Gallery.net | SMF 2.0.19 | SMF © 2021, Simple Machines | Terms and Policies