[TowerTalk] surge protectors

[Jim Thomson]

Date: Thu, 29 Jul 2010 21:54:40 -0400
From: "Pete-N4KW" <n4kwpete at centurylink.net>
Subject: Re: [TowerTalk] surge protectors


Hi Bill,  Will be looking forward to your return.  I purchased mine through 
Florida Power.  They mount it behind the electric meter.  It has two led's 
to monitor the line which you can see.  If at any point one side detects a 
spike or surge the unit will open up and protect the interior of your home. 
By doing so the led goes out, when that happens you call them and they will 
come out and replace the surge protector on your line.  The service along 
with the protector cost me 5 bucks a month and appears on my electric bill.
73 Pete N4KW

##  at the Telco I just retired from, we use JOSLYN brand  surge protector's   for 
everything from  208/120 - 450 kva   office's  and also 2000 kva  offices...[3 phase]
The Joslyn's are also used on all 2860 of our cell sites... and also on the small stuff in the field..
"switch in a ditch"   + some dsl in the field install's etc.  

## The typ  Joslyn setup consist of 2"  square x 3/4'" thick mov's.... EACH wired
from HOT to NEUTRAL.  So 2 used for  typ 240/120.   And 3 used for 208/120. 
Each mov has a 20A slow blow fuse on it's input.   At the output of each mov, it's wired 
directly to neutral buss. At the output of the FUSE, a 120 vac neon is wired to neutral.
Also, a 4PDT  120 vac relay is wired between output of same fuse... to neutral. 
Think of it as 2 x MOV's  in series, across the 240 line..with the Neutral going to the CT. 
The idea is you are protected  with a transient/surge on either hot leg.. and also
both legs.. in the case of a transient coming down both legs simultaneously.  IE:   your 240
vac  linear "see's"  a 780 vac spike across both hots... and the series mov's  will conduct,
and short out the spike.   If the transient/spike is on one leg only, then only one mov
will conduct... and protect any 120 vac  devices on that one leg.   

## so for single phase 240/120.... you end up with 2 x mov's, 2x fuse's,  2 x neons,
and 2 x relay's. ALL of that sits in one box... which resides directly below the main panel..
and wired directly to main panel's buss..with a real short piece of conduit.   With 208/120
3  phase, you have  3x  of everything.. and all 3 x mov's wired  hot to neutral. 

## In normal operation, both relays have their coils  energized 24/7.  Both neons are lit
24/7.   Now if either /both mov's  take one too many hit's... and one /both mov's 
shorts out,  one/both mov fuses will blow open.  Since no more 120 vac  at the output
of the the fuse [ which is the input of the mov]... one/both neons  will go dark.   Also,
one/both relay's will drop out.   When one/both relay's  drop out... a grnd sitting on the 
NO contact is now fed to the COM... and then wired back to the Harris alarm box.  Alarm
comes on.. and fed to main alarm center.  Note, the relays  will also drop out/neons go dark
with any power failure.  The alarm center already has a separate..'commercial AC fail' alarm,
so they can easily distinguish between  a  commercial AC power fail.... and  a blown MOV. 

## Joslyn claims their MOV's  will repsond in < .5 NANOSECOND. Replacement of any MOV  will
depend on it's joule rating.
Size em too small, and you will end up replacing em more often. MOV's are just a bunch
of series 'grains'.. and every time the mov takes a hit, a few more grains here and there
will short out.  Eventually, the 250- 277 vac rated mov's  will drop down in V rating to the
point where one more good hit.. and they will conduct permanently... and blow the SB input fuse. 
[Then you have zero protection on that leg].   

## If the power co is charging $5.00  per month.... and that ALSO includes the protector +
install, then it's a good deal.  IF you have to buy their protector, and also pay for the install, then
it's a scam.  At $5.00 per month x millions of customers = enhanced profits !   Then they only have
to actually have somebody come out to change out one/both movs... which is abt a 3 min job at most. 
Total number of change outs in one year is probably very miniscule  VS total number customers,
even in Florida.   Say a lightning induced surge  blew out every MOV on both sides of a street, the
pwr co  can replace every mov on that street pretty quickly.  They are all concentrated in one
area!   One truck could do em all in 1-2 hrs flat.   How many folks are even gonna check to see if their
neons / leds are both lit ??    I can't see some old bitty traipsing down to the cellar  every month to check
neons/leds.  

## In 34 yrs at the telco, including central offices, switch in the ditch, cell sites, and microwave sites,
mountain top sites, etc, I remember all of 2  x  MOV's  ever being replaced.  I looked after all the Harris alarm
equipment  for the last 10 yrs I was there..and also had access to every outstanding alarm in the co, including 
all alarm history..for all of  VE2/6/7 land.    Those Joslyn brand protector's are an industry standard... and bullet proof for the most part.
You install em once... and they sit there  for the next 40 yrs.  Meanwhile, everything downstream is happy. 
There is no point in installing  puny, undersized mov's.... unless you want to be replacing em on a regular basis,
which in the long run,saves you absolutely nothing.  Beware, some of the mov's out there have really slow rise
times to em, and react too slow.  The peak voltage can get very high, before they conduct.  In some cases, that will
offer minimal / zero protection to devices downstream.  Most homeowners are allowed to do their own wiring, without
an electrical ticket  [their own home, not somebody else's].  Any ham that can run in /wire up a 120/240 line/ breaker 
can easily install a surge protection device.   The ones we used at work were plane jane simple.  Joslyn has more elaborate
types with everything from "event counter's"   with time/date stamps on em.. to  units that will send that same info  via
lan/ethernet, etc.   Some will even tell you the max peak voltage and  duration of a given hit.  Now you are into serious $$. 
http://www.tnbpowersolutions.com/joslyn?site=joslynsurge

They now claim they will protect L-N   L-G  N-G  and L-L   You can also now get em with an optional transient  
filter.. and also an optional  RFI filter and optional SS enclosure.   They are not cheap, but do come with a 10 /15 year warranty.  They are built like
a tank.  Check out their specs.  Most will handle 3000+   10KA events.  And most require NO fuse or breaker.. and can be connected directly
to your main 200A panels buss.  [Most have a  200KAIC fault rating..so no upstream breaker / fuse required]   You can alarm em
any way you want, audible's, lights, etc. 

later... Jim   VE7RF