
People buy the UPS (Uninterruptible Power Supply) to achieve two goals: saving their work when (again) the power cuts off and to protect their precious equipment from nasty things often happening in the power line — spikes, surges and sags.
Let's see how two UPSes - one from the leading world manufacturer APC, and another one with obscure name, but available in many computer shops in Thailand, are designed to cope with these tasks.
APC BackUPS, |
Cheap UPS, |
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| Case and chassis: sheet metal. Provides good heat dissipation, prolonging the life of the battery. In case of the fire inside, gives some fire proofing. |
Case is made of thick plastic. Poor heat dissipation leads to overheating, which damages the battery. Fire unsafe (plastic melts and burns). No common ground inside. | |
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| Printed circuit board as it should look like | No, that's not a damaged UPS - that's a soldering quality... Somebody forgot to remove the flux... | |
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| Classic filter and surge suppressor. MOV, 2 coil Inductors, hot-neutral capacitor and 2 capacitors to the ground. Relays disconnect both hot and neutral wires. |
MOVs only? Relays missing? I wonder how did the developers know which wire is the hot one? What if the user reverse the plug with 2 pins? With this poor schematics MOVs will degrade quickly. | |
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| Simple Push-To-Reset circuit breaker on the back side |