RE: [Repeater-Builder] MOVs for power supply primary
OK, you're looking for something in the middle then. For parallel protectors, LEA CFS or SP series, or Transtector Apex II, may be more in the price range you're looking for (under $1000). Since I don't use protectors of that kind regularly, I don't have any other recommendations other than to stick with repetuable manufacturers and read the data sheets. The cheaper ones will probably be MOV-only. Others may use a combination of MOV's, SAD's, and/or gas discharge tubes. There are pros and cons to each... I don't know of any series protectors that fall into the price range of what I would think you're looking for. Someone else (Eric?) mentioned Square D. The only Square D ones I've used are the ones that are built into the panel (Surgelogic or something like that?), not the add-on ones. We had to replace one in a 3-phase 480/277 panel not too long ago, that's the only reason I'm familiar with them (they have an audible alarm that goes off when the arrestor detects a fault, a nice feature). --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Wednesday, June 09, 2010 8:51 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MOVs for power supply primary OK, I'm familiar with those single-point grounding panel protection devices. How about a service panel protector for home use? And a service panel protector for a small (200A) 3-phase panel? I ask, rather than simply Google for it, because Google could come up with some units that are not good. Chuck WB2EDV
RE: [Repeater-Builder] MOVs for power supply primary
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...@broadsci.com 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
Re: [Repeater-Builder] MOVs for power supply primary
OK, I'm familiar with those single-point grounding panel protection devices. How about a service panel protector for home use? And a service panel protector for a small (200A) 3-phase panel? I ask, rather than simply Google for it, because Google could come up with some units that are not good. Chuck WB2EDV - Original Message - From: Jeff DePolo j...@broadsci.com To: Repeater-Builder@yahoogroups.com Sent: Wednesday, June 09, 2010 1:13 PM Subject: RE: [Repeater-Builder] MOVs for power supply primary 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...@broadsci.com 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 Yahoo! Groups Links
RE: [Repeater-Builder] MOVs for power supply primary
Chuck, Square D makes a line of heavy-duty, commercial-grade surge protectors for both 120/240 VAC residential and 208Y/120 VAC commercial systems: http://tinyurl.com/27tnma7 These are very good products, but- like any really good stuff- are definitely not cheap. I guess that one's definition of cheap changes after suffering a $5,000 loss due to a lightning strike! 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Wednesday, June 09, 2010 5:51 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MOVs for power supply primary OK, I'm familiar with those single-point grounding panel protection devices. How about a service panel protector for home use? And a service panel protector for a small (200A) 3-phase panel? I ask, rather than simply Google for it, because Google could come up with some units that are not good. Chuck WB2EDVsnip snip
Re: [Repeater-Builder] MOVs for power supply primary
Thanks Eric. Chuck - Original Message - From: Eric Lemmon wb6...@verizon.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, June 09, 2010 10:07 PM Subject: RE: [Repeater-Builder] MOVs for power supply primary Chuck, Square D makes a line of heavy-duty, commercial-grade surge protectors for both 120/240 VAC residential and 208Y/120 VAC commercial systems: http://tinyurl.com/27tnma7 These are very good products, but- like any really good stuff- are definitely not cheap. I guess that one's definition of cheap changes after suffering a $5,000 loss due to a lightning strike! 73, Eric Lemmon WB6FLY
Re: [Repeater-Builder] MOVs for power supply primary
It's an Onan 4CCK-3R/1J 1800 RPM, 10 HP, 2 cylinder, gasoline, 3.5 KW, 4 KW surge, from 1965 with 57 hours use on it. In the 2003 Northeast USA power blackout, it ran two homes, including two refrigerators and a freezer. Perhaps not a home-size unit, but the advantage is that is sips gasoline at a low rate. After three days of the 2003 power failure, we had used up the stored gasoline and I was beginning to siphon fuel from the vehicles, as no gas stations were operational. My Comcast broadband Internet was gone after the first hour and my dialup IP answered and connected, but nothing past their site. I had just removed my Direc satellite Internet service two months before. Since Comcast cable TV wasn't there, I connected an outside antenna and was able to get the Detroit TV stations 50 miles away. It was nice to be able to see the stars again, without all the light pollution. My Astron VS-50M has a 10 Ampere fuse in it, but apparently there wasn't enough remaining current available from the generator to open it. I added the GE 130 Volt MOV (from Newark) to the Astron myself. I took my MOV out and everything works fine. My first impulse was that there was a problem with the generator, until I isolated the symptom to that Astron and I realized that plus 10% voltage was tripping my MOV. Ray Brown wrote: - Original Message - From: AA8K73 GMail aa8...@gmail.com mailto:aa8k73%40gmail.com I added a 130 Volt MOV across the hot and neutral of an Astron 50 Amp power supply for a repeater and had an interesting effect. We lost AC power and switched over to the generator. When the load was added to the generator, the Onan's voltage sagged a bit and the throttle opened to bring the speed back. It overshot slightly and was high enough to trip the MOV. That short slowed the generator down until the voltage was too low and then the generator sped up again. And again it fired the MOV and slowed down until it cleared. It kept oscillating with huge voltage swings until I unplugged the Astron power supply. That's very interesting, all right. Was this a single-cylinder 3600 RPM generator, or was it one of the twin-cylinder motor-home generators? I used to work for an Onan distributorship back when (70's) and we had a similar problem with a Southwestern Bell setup. They had a 2.5 LK, which was a single cylinder genset that ran at 1800 RPM. They switched a 500 watt load in and out several times a minute. When the 500 W load hit, it did the same thing you had described. I brought up a 1 KW load (heater elements) and plugged them in the circuit full-time, and it worked like a champ, going between about 40% and 60% of full load. Pretty stable. :-) Ray, KB0STN Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] MOVs for power supply primary
Jeff - Could you suggest some makes and models and maybe explain why they are superior to others? Chuck WB2EDV - Original Message - Good surge arrestors/TVSS's are expensive, and like most things in life, you get what you pay for. If your site has a good surge arrestor at the service entrance, you really shouldn't need anything extra. --- Jeff WN3A
Re: [Repeater-Builder] MOVs for power supply primary
And, boy were there stars! Chuck WB2EDV - Original Message - It was nice to be able to see the stars again, without all the light pollution. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
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 -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Tuesday, June 08, 2010 11:34 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MOVs for power supply primary Jeff - Could you suggest some makes and models and maybe explain why they are superior to others? Chuck WB2EDV - Original Message - Good surge arrestors/TVSS's are expensive, and like most things in life, you get what you pay for. If your site has a good surge arrestor at the service entrance, you really shouldn't need anything extra. --- Jeff WN3A
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...@broadsci.com To: Repeater-Builder@yahoogroups.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
RE: [Repeater-Builder] MOVs for power supply primary
I use Tripplite Isobar Ultra. Usually ends up with the power switch rocker blown across the room when hit hard but equipment is well protected. Wa9ne -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Tuesday, June 08, 2010 3:48 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 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.829 / Virus Database: 271.1.1/2923 - Release Date: 06/08/10 01:35:00
Re: [Repeater-Builder] MOVs for power supply primary
Don't use Radio Shack. You're just asking for trouble. Buy from a quality supplier. Others on the list can give you preferred vendors. Don, KD9PT - Original Message - From: kq7dx To: Repeater-Builder@yahoogroups.com Sent: Monday, June 07, 2010 7:38 PM Subject: [Repeater-Builder] MOVs for power supply primary Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. Thanks for the help.. 73s
Re: [Repeater-Builder] MOVs for power supply primary
I added a 130 Volt MOV across the hot and neutral of an Astron 50 Amp power supply for a repeater and had an interesting effect. We lost AC power and switched over to the generator. When the load was added to the generator, the Onan's voltage sagged a bit and the throttle opened to bring the speed back. It overshot slightly and was high enough to trip the MOV. That short slowed the generator down until the voltage was too low and then the generator sped up again. And again it fired the MOV and slowed down until it cleared. It kept oscillating with huge voltage swings until I unplugged the Astron power supply. Sigh. kq7dx wrote: Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. Thanks for the help.. 73s
Re: [Repeater-Builder] MOVs for power supply primary
- Original Message - From: AA8K73 GMail aa8...@gmail.com I added a 130 Volt MOV across the hot and neutral of an Astron 50 Amp power supply for a repeater and had an interesting effect. We lost AC power and switched over to the generator. When the load was added to the generator, the Onan's voltage sagged a bit and the throttle opened to bring the speed back. It overshot slightly and was high enough to trip the MOV. That short slowed the generator down until the voltage was too low and then the generator sped up again. And again it fired the MOV and slowed down until it cleared. It kept oscillating with huge voltage swings until I unplugged the Astron power supply. That's very interesting, all right. Was this a single-cylinder 3600 RPM generator, or was it one of the twin-cylinder motor-home generators? I used to work for an Onan distributorship back when (70's) and we had a similar problem with a Southwestern Bell setup. They had a 2.5 LK, which was a single cylinder genset that ran at 1800 RPM. They switched a 500 watt load in and out several times a minute. When the 500 W load hit, it did the same thing you had described. I brought up a 1 KW load (heater elements) and plugged them in the circuit full-time, and it worked like a champ, going between about 40% and 60% of full load. Pretty stable. :-) Ray, KB0STN
Re: [Repeater-Builder] MOVs for power supply primary
I agree fully with NOT using Radio Shack low quality run-off manufacturer seconds. Use NTE 140V. The trick is you need to use THREE. One across the hot and neutral. one from hot to ground and one from neutral to ground. MOV's are a funny dog they do not usually short but degrade very quickly depending on number of incoming spikes they suppress. Used them alot to supress the reverse EMF in electromagnetic locking devices, 8+ H, yes henrys! , not micro or milli. suggest replacing annually. Kevin --- On Mon, 6/7/10, kq7dx kq...@yahoo.com wrote: From: kq7dx kq...@yahoo.com Subject: [Repeater-Builder] MOVs for power supply primary To: Repeater-Builder@yahoogroups.com Date: Monday, June 7, 2010, 8:38 PM Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. Thanks for the help.. 73s
RE: [Repeater-Builder] MOVs for power supply primary
Two things leap out at me: Your generator has some very serious regulation problems, and may be undersized, and your Astron power supply must not have the correct fuse installed. If the MOV fires, the fuse is sized to blow instantly. That said, Astron has been known to install MOVs that have a wide tolerance, and those near the low end may go into avalanche mode at only a few volts above nominal 120 VAC. The national standard for nominal utilization voltage is 120 +/- 5%. That means the utility can supply anything between 114 and 126 VAC and be within the required tolerance. 126 VAC is darned close to 130 VAC, and that MOV is already getting hot! 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of AA8K73 GMail Sent: Monday, June 07, 2010 6:47 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MOVs for power supply primary I added a 130 Volt MOV across the hot and neutral of an Astron 50 Amp power supply for a repeater and had an interesting effect. We lost AC power and switched over to the generator. When the load was added to the generator, the Onan's voltage sagged a bit and the throttle opened to bring the speed back. It overshot slightly and was high enough to trip the MOV. That short slowed the generator down until the voltage was too low and then the generator sped up again. And again it fired the MOV and slowed down until it cleared. It kept oscillating with huge voltage swings until I unplugged the Astron power supply. Sigh. kq7dx wrote: Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. Thanks for the help.. 73s
Re: [Repeater-Builder] MOVs for power supply primary
Harbach sells a set of three that is for the SB-220. You might look at them. 73, Dick, W1KSZ -Original Message- From: kq7dx kq...@yahoo.com Sent: Jun 7, 2010 8:38 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] MOVs for power supply primary Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. Thanks for the help.. 73s Yahoo! Groups Links
RE: [Repeater-Builder] MOVs for power supply primary
I replaced two in two ASRON power supplies that got zapped with 220 and seem to be still working. I would recommend getting a good brand if you have the resource. Mike Mullarkey K7PFJ _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kq7dx Sent: Monday, June 07, 2010 6:39 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] MOVs for power supply primary Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. Thanks for the help.. 73s
RE: [Repeater-Builder] MOVs for power supply primary
Regarding your last question, an MOV normally will go into avalanche mode when the applied voltage exceeds its threshold value. It becomes a low shunt resistance, which should blow the input fuse in the device it is protecting. Once the voltage is removed and the MOV cools off, it usually recovers. However, usually is not always the case, so it may be prudent to replace all three MOVs after a surge event. As others have noted, an MOV rated at 130 VAC is suitable for a 120 VAC appliance only if its tolerance is tight, say +/- 2%. You won't find these at Radio Shack. It may be a good idea to install MOVs rated at 140 VAC with a 10% tolerance. Always protect the device with a fuse sized as recommended by the manufacturer, and don't substitute a fast-blow fuse for a time-delay fuse, or vice-versa. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kq7dx Sent: Monday, June 07, 2010 5:39 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] MOVs for power supply primary Hello to group, Is putting an MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea? I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. Also, are the MOVs that radio shack sell any good? Rated at 130VAC. Any body used them? Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working? Thanks for the help.. 73s
RE: [Repeater-Builder] MOVs for power supply primary
Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. I'm not that big of a fan of MOV's, but if you really feel the need to add them across the transformer primary, as long the input to the power supply is properly fused, whatever floats your boat. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... I'm not sure that there's anything that Radio Shack sells any more that's any good, is there? Seriously, I'd buy Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. My experience that small MOV's fail in one of two ways. Either they fail shorted, quite often with no outward visible signs, or they fail open catastrophically as a zillion pieces of shrapnel that can cause damage to nearby components, wiring, people, livestock, etc.. Another downside to MOV's is that after they've successfully quenched an over-voltage event of any significant energy, their clamping voltage changes. So, you may end up with less and less protection over time. Good surge arrestors/TVSS's are expensive, and like most things in life, you get what you pay for. If your site has a good surge arrestor at the service entrance, you really shouldn't need anything extra. --- Jeff WN3A
RE: [Repeater-Builder] MOVs for power supply primary
There is no reason to have to put them period. Extra protection is well.. to each his own. MOV's are not the greatest, but certainly wont hurt Kevin B.S.E.E. --- On Mon, 6/7/10, Jeff DePolo j...@broadsci.com wrote: From: Jeff DePolo j...@broadsci.com Subject: RE: [Repeater-Builder] MOVs for power supply primary To: Repeater-Builder@yahoogroups.com Date: Monday, June 7, 2010, 11:54 PM Hello to group, Is putting a MOV from hot to ground, neutral to ground, on the primary of the transformer of the power supply a good idea.. I have a ICE surge suppressor on in front as well but thought I would put more inside the supply for back up. I'm not that big of a fan of MOV's, but if you really feel the need to add them across the transformer primary, as long the input to the power supply is properly fused, whatever floats your boat. Also, are the MOVs that radio shack sell any good. Rated at 130VAC. Any body used them... I'm not sure that there's anything that Radio Shack sells any more that's any good, is there? Seriously, I'd buy Last question: when MOVs fail or take a surge do they fail in a shorted condition taking out the fuse till the MOV can be replaced, or do they blow or fail open leaving the supply working. My experience that small MOV's fail in one of two ways. Either they fail shorted, quite often with no outward visible signs, or they fail open catastrophically as a zillion pieces of shrapnel that can cause damage to nearby components, wiring, people, livestock, etc.. Another downside to MOV's is that after they've successfully quenched an over-voltage event of any significant energy, their clamping voltage changes. So, you may end up with less and less protection over time. Good surge arrestors/TVSS's are expensive, and like most things in life, you get what you pay for. If your site has a good surge arrestor at the service entrance, you really shouldn't need anything extra. --- Jeff WN3A
