ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

Topic Options
Rate This Topic
#168985 - 09/23/07 08:06 AM Phone Lightning Arrestor
Admin Offline

Administrator
Member
Registered: 10/07/00
Posts: 3417
Loc: NY, USA
Quote:
I found this in an old sewage pumping station contol panel. It's from the mid 70's. Enjoy!

- Pappster855 (Ian)







Top
Tools for Electricians:
#169005 - 09/23/07 12:46 PM Re: Phone Lightning Arrestor [Re: Admin]
NJwirenut Offline
Member
Registered: 09/15/01
Posts: 806
Loc: Bergen County, NJ
Yeah, those are neat looking things. I have one of them in my tube collection. Yours apparently took very few "hits" over the years, as the glass isn't blackened and the graphite balls look to be in good shape.

BTW, the "KR-85" marking on the base refers to Krypton-85, a radioactive gas. The tube contains a small amount in order to stabilize the triggering voltage. No hazard at all in a sealed tube, but if it breaks, open the window and air out the room.
Top
#169007 - 09/23/07 12:50 PM Re: Phone Lightning Arrestor [Re: NJwirenut]
renosteinke Offline
Cat Servant
Member
Registered: 01/22/05
Posts: 5316
Loc: Blue Collar Country
Kryptonite? I feel weak .... laugh
Top
#169426 - 10/04/07 05:39 PM Re: Phone Lightning Arrestor [Re: renosteinke]
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
How does it work?
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin
Top
#169442 - 10/05/07 04:23 AM Re: Phone Lightning Arrestor [Re: Trumpy]
NJwirenut Offline
Member
Registered: 09/15/01
Posts: 806
Loc: Bergen County, NJ
3 separate graphite balls in an inert gas atmosphere (Ar+ Kr-85). 1 ball is grounded, and the other 2 connect to the lines being protected.

Under normal conditions, the tube does nothing, but if the voltage on either of the protected lines exceeds a certain value (~150V, IIRC), the gas ionizes, and effectively shorts the line to ground. Once the overvoltage goes away, the gas de-ionizes, and waits for the next surge to come along.
Top
#170789 - 11/11/07 04:11 PM Re: Phone Lightning Arrestor [Re: NJwirenut]
Albert Offline
Member
Registered: 08/16/06
Posts: 76
Loc: Falls Church, VA
And I believe the "7448" marking is a date code, indicating the tube was manufactured in the 48th week of 1974.

Albert
Top

Member Spotlight
Member Since: 04/03/02
Posts: 6775
New in the Gallery:
SE cable question
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box


Who's Online
0 registered (), 85 Guests and 8 Spiders online.
Key: Admin, Global Mod, Mod
 
New in the Gallery:
SE cable question
 
Top Posters (30 Days)
Admin 51
HotLine1 43
gfretwell 17
Trumpy 16
Ruben Rocha 13
 
Newest Members
clee512, Jdscott2005, FAIZAN, Regitest2, sureshazhagai

ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals