when there’s a lot of wind or rain, and the lights dim or flicker for a second, and then immediately kick back on, what is actually happening? I’m asking because it seems like if the power is going to disconnect, it would be from some wire breaking or something. So what is happening when it almost goes out, but it doesn’t?
In: Engineering
All electronics have a hold-up time. How long must electricity be lost before it shuts down? Some electronics, with a shortest time, were microwave ovens and VCRs. As indicated by a flashing clock while everything else worked uninterrupted.
If power goes off longer (ie many tens of milliseconds), all appliances simply power off. International design standards for electronics (long before the IBM PC existed) required all electronics to either work just fine or simply power off. Without any damage. One standard was so blunt about this as to put this expression, in all capital letters across the entire low and no voltage areas on charts: No Damage Region. Outages must never damage any electronics.
What protected electronics in a dishwasher, clock radios, central air, refrigerator, LED & CFL bulbs, TV, GFCIs, garage door opener, dimmer switches, microwave oven, recharging electronics, door bell, digital clocks, and smoke detectors? Invisible UPSes?
UPS has one purpose. To provide temporary and ‘dirty’ power so that unsaved data can be saved. To avert a reboot. Nothing more.
What does a surge protector do? Technically accurate answers are tempered by specification numbers. It has a let-through voltage – typically 330 volts. That means it does absolutely nothing (remains inert) until 120 volts well exceeds 330 volts. When does an outage (120 volts falling to zero) recreate a voltage that is approaching or exceeding 1000 volts? Never. Unfortunately many recommendations are only reiterating what advertising, hearsay, or urban myths promote. And ignore all numbers.
Read specification for that type protector. That $3 power strip with five cent protector parts, selling for $25 or $80, only protects profit margins. Superior protection is already inside electronics.
Sometimes a fault does occur. So power may be interrupted. And then restored by AC utility equipment. Generally, this happens three times. If that fault still exists, then power remains cut off.
Dimming can be due to some massive short on some other circuit. As soon as that other circuit disconnects, then lights return to full intensity. Meanwhile, incandescent bulbs can dim to 50% intensity. Even a voltage that low is perfectly good for all properly designed electronics. Because electronics are required to be that robust.
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