HONOLULU (HawaiiNewsNow) - It sounded like a joke: all city services were interrupted because the uninterruptible power supply was interrupted. But that's apparently what happened. And it could happen to you. An uninterruptible power supply, or UPS, takes the outside electric power and converts it from alternating current to direct current. It stores that direct current in a battery. At the other end, power is reconverted from DC back to AC and flows through your office. Because the UPS unit stores power, if the outside feed goes out, you still have stored-up power flowing out. No interruption. We think that actually happened.
But eventually the stored-up power runs out, especially if your back-up generators aren't on, and especially if everyone is using power, rather than the more limited power we associate with back-up generators. When the UPS unit runs dry, then you DO have an interruption. One interesting side note: the process of converting power from AC to DC and back to AC cleans up the electrical waves going through your wires. That's good for the life of delicate electronics.