Breaker Switch
When I saw the clear plastic rocker, I was expecting an indicator switch. That's not the case, though. The third terminal for the indicator’s neutral connection is missing. Since the top does have LED indicators for ground fault and protection, I concede that such a switch would have been redundant.
Based on the documentation I could find for this protection switch, its trip time can exceed one second at 300% overload. Since distribution panel breakers are at least an order of magnitude faster, that explains why I’ve never seen a surge protector breaker switch trip.
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Internal Wire Gauge
Although the power cord is #14, all of the internal wiring is #16. To be fair, losses in 10cm of #16 are still negligible next to 2.4m of #14, and wiring inside the power bar isn’t as tightly packed as the cord's.
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Broken Strands
Look at that beautifully tinned wire. Unfortunately, four of its strands broke during stripping or preparation. While reviewing photographs, I noticed that double-insulated wires are being used for the hot-side wiring (the central insulation is white with a thin black outer layer). Double-insulated wiring with high contrast layers is used to facilitate visual identification of compromised insulation.
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Slight Nick
At some point during the unit’s assembly, a small chunk of the black wire’s insulation was shaved off, though not enough to reveal the white insulation underneath. We're still good to go.
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Indicator Board
There isn’t much to see on this tiny board. Since all power has to pass through the main thermal cut-off fuse on the surge protection board, the "protected" LED's only job is to show that the surge protector is still receiving power. In other words, the main cut-off hasn’t blown.
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Surge Suppression Board Back
The soldering quality looks pretty good, with minimal flux residue around the manual wire soldering jobs and no apparent cold or under-filled solder joints.
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Surge Suppression Board Top
Where does AmazonBasic’s surge suppression come from? A total of 10 MOVs, the four thicker ones being 20D471s and the rest likely either 20D271Ks or 20D201Ks. I’m guessing here, as none of them face outward for me to read numbers from, and I did not want to rip the tape off. For what it's worth, there is also a tiny 10nF Y-class capacitor on the left.
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Skimping On Filtering
The board layout had provisions for a filter choke meant to separate the first bank of three MOVs (directly across hot and neutral after the thermal shut-off fuse) from the second bank of two MOVs downstream from said inductor.
I was tempted to dig through my scavenged parts bin to find a suitable choke to put in there, but did not find any with suitably thick wire gauge.
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Why Inductors Matter
Inductors oppose any sudden change in the current passing through them, which makes them ideal for rejecting short-lived voltage transients. How much of a difference can a modestly-sized inductor make to the strain put on other transient suppression devices? Here’s a simple test circuit with two quasi-ideal 200V TVSS', one directly across simulated live-neutral and the other with an extra 22µH inductor in series, both branches subjected to the same 6kV pulse source.
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Simulation Results, Current
Inserting a mere 22µH in series reduces peak current through the diode from 2778A to 890A, a 68% reduction in transient suppression strain. Since MOV lifespan is heavily dependent on peak energy dissipation, using inductors upstream to reduce current rise rate and peaks considerably improves the life expectancy of downstream MOVs.
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