Instead of MOVs, how about a gas discharge tube [GDT]. OR Possibly in parallel with the MOV. They are small and metal and the specs say they can take quite a few discharges and not break down.. Anyone use those? Thank you for all the replies and info on my subject!.. 73
--- In Repeater-Builder@yahoogroups.com, "Jeff DePolo" <j...@...> wrote: > > > Hmmm. That's a tougher one. Mostly I use the Polyphasers (PLDO-120US-15A > or -20A) at sites that don't have facility-wide protection. The TrippLite > Isobar Ultra series is another (ISOBAR8ULTRA et al). The Isobars also have > a $50,000 equipment warranty (can't say I've ever had to use it, don't know > how much red tape there is to go through). I like the Polyphasers because > it's designed to mount to a ground panel/bus bar, so I mount it to the bus > bar that has all of my other arrestors (coax, telco, etc.) on it to provide > a common-point ground. The Isobar doesn't have provisions for direct > grounding - it relies only on the equipment grounding conductor in the AC > cord, but the TrippLite has arguably better EMI/RFI filtering than the > Polyphaser. > > --- Jeff WN3A > > > > -----Original Message----- > > From: Repeater-Builder@yahoogroups.com > > [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey > > Sent: Tuesday, June 08, 2010 4:48 PM > > To: Repeater-Builder@yahoogroups.com > > Subject: Re: [Repeater-Builder] MOVs for power supply primary > > > > > > > > OK, I should have been more specific. What would be a > > reasonable unit for a > > repeater site that may have only a couple thousand dollars worth of > > equipment inside? > > > > Chuck > > WB2EDV > > > > ----- Original Message ----- > > From: "Jeff DePolo" <j...@... <mailto:jd0%40broadsci.com> > > > To: <Repeater-Builder@yahoogroups.com > > <mailto:Repeater-Builder%40yahoogroups.com> > > > Sent: Tuesday, June 08, 2010 4:22 PM > > Subject: RE: [Repeater-Builder] MOVs for power supply primary > > > > > > > > Probably the ones I've had the most luck with are the > > Islatrol series from > > > Control Concepts. I think they have been bought out by > > Emerson or Liebert > > > or one of the other companies that have power divisions. > > Anyway, they > > > call > > > these "active tracking filters". They not only are TVSS's > > but also filter > > > noise, low-amplitude spikes, etc. Right now I'm typing from > > a mountaintop > > > site (broadcast) that we re-built a few years ago. We put > > in an Islator > > > I-2100 (120/240V single-phase). The old equipment shelter > > which had been > > > here since 1990 had the same model unit. In the 15+ years we've been > > > managing and maintaining the site, we've had zero > > surge-related failures, > > > and this site sticks out like a sore thumb as far as > > lightning goes. In > > > the > > > last few years I've used the same series of arrestors for > > new site builds > > > at > > > a dozen sites or so and have had no power-related problems. > > > > > > Others that make comparable-quality products include > > Joslyn, Transtector, > > > and Innovative Technologies. > > > > > > There is one big difference (to me anyway) between TVSS's, > > that being > > > whether they are the series or parallel type. Series type takes the > > > utility > > > service (or transfer switch output if there's a generator > > too) as its > > > input, > > > and provides a protected output to feed the panel(s). > > Parallel type is > > > typically connected to a breaker in the panel, which puts > > it in parallel > > > with all of the loads. I much prefer series. Parallel type > > can be less > > > effective because a) there will always be some inductance > > and resistance > > > in > > > the wiring between the panel and the protector, b) if the > > TVSS conducts, > > > there's a good chance it will trip the breaker in the > > panel, resulting in > > > no > > > protection until the breaker is reset, and c) they are much > > less effective > > > as a noise filter. The upside to parallel type is they can > > easily be > > > added > > > at any time just by popping breakers in the panel and feeding the > > > arrestor. > > > Series, on the other hand, are in-line with the service > > conductors, so if > > > you want to add one (or repair one), you have to take the > > service down. > > > Series tends to also be more expensive, especially for > > three-phase and > > > unlike parallel type, the price goes up as the current > > rating goes up for > > > obvious reasons. > > > > > > A good 200A single-phase arrestor of the ilk I'm talking > > about starts at > > > about $1000 and goes up quite a ways from there. I think these > > > single-phase > > > I-2100's were in the $2000 range. I recently spec'ed a > > 120/208 3-phase > > > Transtector (parallel type) for another site where I'm much > > less concerned > > > about power-wise, and that was about $1800. No cheap, but > > where you're > > > protecting equipment in the 6 and 7 figure range, it's a > > no-brainer. If > > > you're repeater is a Micor mobile and an Astron, it might be hard to > > > justify... :-) > > > > > > --- Jeff > > > > > > > > > > >
