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#1
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In article , w_tom
wrote: Any protector that is damaged by the first surge is grossly undersized. No effective surge protector can be damaged. They are not sacrificial devices as urban myth purveyors will claim. The characteristics of MOV's are well known. Every time a MOV turns on due to the device threshold being exceeded they degrade based on how much power is absorbed. If you are whom I think you are the facts won't bother you one bit and further nonsense posts can be expected. -- Telamon Ventura, California |
#2
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A wire also absorbs some power when it shorts a large
current. Does that mean the purpose of a wire is to absorb electricity? Of course not. MOVs are not installed to absorb power. But then if one first consults manufacturer datasheets, then that becomes woefully obvious. http://www.nteinc.com/Web_pgs/MOV.html Let's use the 2V130 as example. This device will shunt up to 4500 amps during the standard 8/20 usec surge. A 1000 volt transient at 4500 amps would be well over 600 joules. But this device is only rated at 39 joules maximum. How can that be? Because MOVs, like wire, are not installed to absorb the energy. They are designed to shunt. If an MOV was absorbing the transient, then MOV voltage must increase as more energy is absorbed. That means more voltage confronts the adjacent appliance. But MOVs don't work that way. If their purpose was to absorb a transient, then they must connect in series with the appliance. But MOVs connect in parallel - a shunt mode device. To be effective as shunt mode devices (like wire), the MOV must conduct massive transients and absorb less of that transient. That is what MOVs do. They shunt. They do not stop, block, absorb, or filter a transient. They operate like a wire during the transient. They shunt. As previously demonstrated from manufacturer datasheets (and not from wild speculation about what 'joules' measures): If that MOV in a plug-in protector that can only withstand 3 standard 8/20 microsecond transient, then the larger 'whole house' protector (that costs about same) will withstand about 300+ such surges. Joules is a measure of MOV life expectancy. MOVs are not designed to absorb a transient - which is in direct contradiction to what many web sites, written by English majors, will claim. The better an MOV, then the more energy it can shunt - per joule. Read manufacturer datasheets; not web sites written by English majors. It is the difference between fact and fiction. Now for your insults - which apparently are due to insufficient electrical knowledge. First learn before insulting others. There is a datasheet. Read it before posting. Keep it civil - if you can. Posted previously are accurate electrical engineering facts taken from manufacture datasheets. Any protector that is damaged by the first surge is grossly undersized - an ineffective protector usually sold to those who like to throw money at urban myths. BTW, MOV degradation is not due to power absorption. It is due to energy absorption - a major technical difference that English majors will not understand. Telamon wrote: In article , w_tom wrote: Any protector that is damaged by the first surge is grossly undersized. No effective surge protector can be damaged. They are not sacrificial devices as urban myth purveyors will claim. The characteristics of MOV's are well known. Every time a MOV turns on due to the device threshold being exceeded they degrade based on how much power is absorbed. If you are whom I think you are the facts won't bother you one bit and further nonsense posts can be expected. |
#3
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In article , w_tom
wrote: A wire also absorbs some power when it shorts a large current. Does that mean the purpose of a wire is to absorb electricity? Of course not. MOVs are not installed to absorb power. But then if one first consults manufacturer datasheets, then that becomes woefully obvious. http://www.nteinc.com/Web_pgs/MOV.html Let's use the 2V130 as example. This device will shunt up to 4500 amps during the standard 8/20 usec surge. A 1000 volt transient at 4500 amps would be well over 600 joules. But this device is only rated at 39 joules maximum. How can that be? Because MOVs, like wire, are not installed to absorb the energy. They are designed to shunt. If an MOV was absorbing the transient, then MOV voltage must increase as more energy is absorbed. That means more voltage confronts the adjacent appliance. But MOVs don't work that way. If their purpose was to absorb a transient, then they must connect in series with the appliance. But MOVs connect in parallel - a shunt mode device. To be effective as shunt mode devices (like wire), the MOV must conduct massive transients and absorb less of that transient. That is what MOVs do. They shunt. They do not stop, block, absorb, or filter a transient. They operate like a wire during the transient. They shunt. As previously demonstrated from manufacturer datasheets (and not from wild speculation about what 'joules' measures): If that MOV in a plug-in protector that can only withstand 3 standard 8/20 microsecond transient, then the larger 'whole house' protector (that costs about same) will withstand about 300+ such surges. Joules is a measure of MOV life expectancy. MOVs are not designed to absorb a transient - which is in direct contradiction to what many web sites, written by English majors, will claim. The better an MOV, then the more energy it can shunt - per joule. Read manufacturer datasheets; not web sites written by English majors. It is the difference between fact and fiction. Now for your insults - which apparently are due to insufficient electrical knowledge. First learn before insulting others. There is a datasheet. Read it before posting. Keep it civil - if you can. Posted previously are accurate electrical engineering facts taken from manufacture datasheets. Any protector that is damaged by the first surge is grossly undersized - an ineffective protector usually sold to those who like to throw money at urban myths. BTW, MOV degradation is not due to power absorption. It is due to energy absorption - a major technical difference that English majors will not understand. Telamon wrote: In article , w_tom wrote: Any protector that is damaged by the first surge is grossly undersized. No effective surge protector can be damaged. They are not sacrificial devices as urban myth purveyors will claim. The characteristics of MOV's are well known. Every time a MOV turns on due to the device threshold being exceeded they degrade based on how much power is absorbed. If you are whom I think you are the facts won't bother you one bit and further nonsense posts can be expected. The notorious Tom troll. Explaine the meaning of the chart "Peak current per pulse versus pulse duration" at the top of this page. http://www.worldproducts.com/MOVPeakPulse.htm I see you are still up to par with your long winded nonsense and you still have not learned to post to Usenet properly either. Up next... a kill file update. -- Telamon Ventura, California |
#4
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In article
, Telamon wrote: snip Telamon wrote: In article , w_tom wrote: Any protector that is damaged by the first surge is grossly undersized. No effective surge protector can be damaged. They are not sacrificial devices as urban myth purveyors will claim. The characteristics of MOV's are well known. Every time a MOV turns on due to the device threshold being exceeded they degrade based on how much power is absorbed. If you are whom I think you are the facts won't bother you one bit and further nonsense posts can be expected. The notorious Tom troll. Explaine the meaning of the chart "Peak current per pulse versus pulse duration" at the top of this page. http://www.worldproducts.com/MOVPeakPulse.htm I see you are still up to par with your long winded nonsense and you still have not learned to post to Usenet properly either. Up next... a kill file update. Answering my own post because Tom can't. I figured you could not answer a simple question. -- Telamon Ventura, California |
#5
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Posted by worldproducts.com is a chart demonstrating MOV
life expectancy for various pulse widths and peak current - as was described in the previous post. Chart simply demonstrates how an MOV degrades; not self destructs. As stated earlier, an MOV self destructs when operating well outside the ratings of that chart - when grossly undersized - insufficient joules to provide effective protection. Any MOV that 'sacrifices itself' does not even appear on the chart and does not provide effective protection. Any MOV that 'sacrifices itself' was grossly undersized - ineffective protection. Telamon wrote: Explaine the meaning of the chart "Peak current per pulse versus pulse duration" at the top of this page. http://www.worldproducts.com/MOVPeakPulse.htm I see you are still up to par with your long winded nonsense and you still have not learned to post to Usenet properly either. Up next... a kill file update. |
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