The Grid: The Fraying Wires Between Americans and Our Energy Future

Heard yesterday on Fresh Air: Aging And Unstable, The Nation’s Electrical Grid Is ‘The Weakest Link’

In her new book, The Grid, Gretchen Bakke argues that the under-funded power grid is incapable of taking the U.S. into a new energy future. She explains the challenges to Fresh Air‘s Dave Davies.

Just ordered a copy online; was a great interview and sounds like a wonderful book, dealing with the realities of balancing nearly unlimited, yet inconsistent renewable power sources (solar, wind, etc.) with the reality of consumer and commercial demand.

I confess to being a little curmudgeonly about issues of power usage, renewable energy sources, attempts to encourage consumer energy savings, etc. and this book gets to the heart of a lot of that. Really looking forward to this read!

Losing the Neutral Conductor

This one came across my social media timeline this morning (edited a bit):


I came home on Friday, an hour before we had a birthday party planned. There was a cable company guy who came over and asked if I was the home owner. He did not explain the problem very clearly and became very frustrating but in short, he saved our house from burning down.

He shut down the Internet and told us to shut down the electricity. Apparently the neutralizing wire that runs under ground was not working causing brown outs and power shortages. The smell of electrical fire was heavy in the house.

We managed to have a great party despite the problems. The output caused a shortage in the hot tub and pool. We have no refrigeration or dishwasher along with a few other things that burned out. Last night, we found a power strip that had really burned out with burn marks on the floor. As he moved it, the same electric burn smell filled the room.

Through it all God spared us big. We are still without a refrigerator but at least the stove works.


What happened was that this home lost the neutral conductor from the utility to the service entrance. Without that neutral, there’s no return path except for the safety ground, which is often substandard or high impedance (~25 ohms). The result: Phase-Phase voltages (such as used for an electric stove, water heater, or electric dryer) are fine, but Phase-Neutral voltages can be anywhere from 0 VAC to 240 VAC.

So yes, things blow up, burn, etc. and often in a bad way (high current but not a dead short, so not enough to trip breakers). The “power strip with burn marks on the floor” is typical as internal surge suppressors / MOVs overheat, not because of short term transients, but because of prolonged, sustained AC overvoltage.

Oftentimes this sort of situation has some warning signs: lights dimming or brightening as appliances switch on and off, light bulbs failing prematurely. One online board reports:


When i turned the oven on, the fan went back to normal, the lights normal.  The 240v load
apparently balanced the system.


Sadly, a lot of electricians and utility workers are not that well versed in this sort of issue. From the same message board:


So i get on the horn with the power company.  They come out, and basically look at what i’m experiencing and the first thing the guy does is pull the meter.  Then he measures the voltages on the incoming legs.  All is equal.  Then he tells me the problem must be on the inside.  Puts the meter back in and the imbalance returns.  “yep , he says, problem is on your side”.


 

No Current? No Problem!

We recently looked at Fluke 1750 data from an ultrasound site. As is often the case with these 120 VAC, 1 Phase monitoring, it’s voltage only (due to the need to use a break-out cable to monitor current on a manufactured power cord; even if they are made up and sent with the monitoring equipment, they tend to disappear from the power analyzer kits over time.

A lack of current data can be a real handicap when analyzing data, but we go back a few years, to the days before current monitoring was ubiquitous. Here’s a few things we were able to determine, even without current data.

Ultrasound OutageFirst, an outage was captured, identified by the service engineer as “hospital power went out”. We’re not so sure; the rapid loss of voltage, with no significant decay, points to a local event (not facility wide), and the neutral-ground voltage swell and phase voltage collapse points to a high current event. Our best guess – equipment fault caused an overload and a subsequent breaker trip.

Ultrasound TransientsNext some voltage transients, captured a few times during monitoring, on both phase-neutral and neutral-ground. Without current data, it’s hard to make much of a guess regarding the source of these. But zooming out a bit provides additional evidence.

Ultrasound Switch-onRMS voltage logs show some small drops in voltage immediately after the transient – typical of a load switch-on (neutral-ground data, not shown, also supports this). We’re sure the transients are associated with load switch-on; probably switch bounce of a circuit breaker, relay, or contactor.

Power analysis without current data. Kicking it old school…..