Edward Vielmetti | AnnArbor.com

Did your lights go dim? More to the point, I'm wondering why my lights went dim, and what is there about the power network in this area that causes lights to dim but other things, like my computer power charger, to keep working?

Above is a quick brownout and blackout map. A DTE Energy substation in the area, on Hoover Street near the Ann Arbor Railroad tracks, is noted with a question mark. You can edit the map on Google Maps to add your report or leave a report in the comments below.

What is a brownout?

If systems are not designed for low or fluctuating voltage, they can be damaged by power brownouts. Sensitive electronic equipment with power supplies that are not designed for adverse conditions will fail, either by resetting or failing in mysterious ways. Electric motors, like the compressors in air conditioners or refrigerators, will stop running.

A brownout condition means that the voltage provided at the wall socket is lower than normal, and thus the system provides less energy to the circuit. Some equipment will tolerate a relatively wide deviation range of voltage input, e.g. the auto-switching Apple iMac G5 power supply, which handles a range of 100-240 volts to produce an 80 watt output.

One way that systems deal with voltages outside of the design range is to shed some of the excess energy as heat. This can lead to dangerous situations, as power supplies and motors generating heat instead of light or motion.

The video below shows what an apartment looks like in an extreme brownout situation. The author uses a digital multimeter to measure line voltage, and then shows the various appliances in his place that have stopped working.

Systems engineering

In looking around for experts in the area who would actually know this material, I found the EECS Systems Laboratory, located on the University of Michigan's North Campus.

The Systems Lab notes that Michigan native Claude Shannon is the father of information theory: "Born in 1916 in Petoskey, Michigan, and raised in Gaylord, he obtained two bachelor degrees from the University of Michigan in 1936, on one in electrical engineering and a second in mathematics. His pioneering work on the theory of information laid the foundations for the modern era of digital communications."

Modeling, Analysis and Control of DC Hybrid Power Systems is a Ph.D. thesis by U-M graduate Yanhui Xie. The work is further described by "Analysis and modeling of a DC hybrid power system testbed for power management strategy development," which goes into some of the extensive efforts needed to make sense of the systems that go into electric powered vehicles.

Brownout as a metaphor

You don't have to go too far to get to the point where people stop thinking about brownout from the electrical systems world and start applying that metaphor — of systems which are still working, but not quite all the way — to other fields.

Jolts, Surges, Brownouts, and Blackouts: Shocks to Stable Energy Policies: "A brownout produces negative consequences but only for a short duration and to a limited degree. A brownout saps the power of an electrical system without stopping it completely or breaking the mechanisms of distribution. In a policy system, a brownout may occur when the demand for a particular good or policy is much higher than the system’s ability to provide it. Examples from energy policy may be long lines at gas stations during the 1973 Oil Embargo or the unmet demand for renewable energy technologies since then."

The US EPA lab in Ann Arbor environmental plan from 2003 notes: "Grassy areas are allowed to brown out during dry periods. No irrigation is used to maintain facility landscaping. Grassy areas are allowed to brown out during dry periods, and are naturally restored when precipitation occurs."

In aviation, a brownout happens when helicopter downwash obscures visibility for landings. In Sensor Technology to Aid Obscured (Brownout) Helicopter Landings, Frederick Smith, the CEO of Ann Arbor-based OptiMetrics Inc., spoke to U-M students in a Tau Beta Pi gathering in 2009.

Edward Vielmetti is the lead blogger at AnnArbor.com. Contact him at edwardvielmetti@annarbor.com.