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Cable TV In-Line Coaxial Surge Protector
How does this device shunt a surge with no apparent ground connection?
One would think that surge protection would require a heavy ground in order to carry the energy of the surge away from the device and the equipment it is protecting. How is protection achieved?
This device is a non-ohmic variable resistor, or varistor. Varistors do not shunt surges. This would imply redirection of the current to another path such as ground. This is not how varistors work. Normal operation of a varistor is shunt mode, whereby current bypasses the varistor and is allowed to flow through the circuit unimpeded. When input voltage is higher than the clamping voltage, i.e. a surge, the varistor's resistance increases infinitely, cutting off the flow of current. Resistance dictates current flow. When resistance is sufficiently high, current will not flow. See Ohm's law.Note that varistors degrade after each surge, and can degrade rapidly, or simply fail, after an extremely large surge, such as a lighting strike. Therefore, this is a consumable deivce. Given the low cost, for maximum continuous protection, it is a good idea to replace this device once a year if you live in the Midwest, or anywhere electrical storms are frequent. Definitely replace it immediately after a nearby lighting strike.No specs are given for this low cost unit. I'd suspect its joule rating is very low. Running 2 of them in series will double your protection. Normally I install a single large value suppressor at the inside distribution panel. With this product you'd probably want to install two to four in series at the panel for maximum protection. As it has male/female connections it is apprently designed with this in mind, else it would be double female.
Date published: 2012-12-16
What is the RF loss?
THe -Insertion Loss: Less than 0.2 dB Video-1500 MHz -Return Loss ( 75 ohm):16dB
Date published: 2013-04-24
What's the frequency range?
The previous question on the loss gives an answer for loss to 1500 MHz, but other sites list this same part (including PE model) as covering 5-2300 MHz.
The specs on current stock are below:Current stock Surgender SE-1 specs- Surge Protection Attack Time:0.0000001 seconds (100 nanosec.) -Maximum Surge Current: 5000 Amps. (8 microsec x 20 microsec test pulse) -Maximum Surge Voltage:Multiply 5000 times Ohms of Coax Loop -Surge life: 200 Surges of 500 Amps. (10 microsec x 1000 microsec test pulse) -Normal Resistance Across Coax: 10,000 Mega Ohms -Surge Resistance: Approx. 0 Ohm -Power Passing Capability:50 Volts DC or AC peak-to-peak 36 Volts RMS, 10 Amps -Insertion Loss: Less than 0.2 dB Video-1500 MHz -Return Loss ( 75 ohm):16dB (VSWR 1.38) Video to 500MHz -14dB (VSWR 1.38) 500 to 1500MHz -Connectors: F Fmale to F Female -Dimensions:1.385"L x 0.815"DIA.
Date published: 2013-06-10