OT: Don't mess with my AC

**bfish** · June 25th, 2011, 08:52 PM

Power grid change may disrupt clocks | The News Journal | delawareonline.com

Not a real headline grabber... yet.

Seems we're gonna be the test animals this time. The idea to run it a year to see if anyone notices was pure brilliance.

For lots of stuff it won't matter. For anything with a synchronous motor (like the Hammond organ, most RTRs and TTs, etc) it's bad news. Plenty of digital devices clock off the AC too.

And in the recording world... will a CD recorded when the AC was 59Hz sound right played back at 61?

Might be a good time to enter the Power Frequency Stabilizer market.

**cradeldorf** · June 26th, 2011, 02:32 AM

I think they've been doing it for years, they run it at 59 during working hours to slow the clocks down and get more work out of you then speed the damn things up to 61 so you have to get back to work faster!!!!

**Panomaniac** · June 26th, 2011, 12:15 PM

I knew it!!

**bfish** · June 26th, 2011, 02:03 PM

Seems a private outfit called NERC has been handling our grid for a few years, and they proposed the "experiment". Assertions are that we may be wasting big bucks on precision we don't really need.

Which raises the Q, "how precise is it now"? I found the following alarm limits at NERC;

" The Frequency Trigger Limits (FTLs) are defined as thresholds. An FTL-Low alarm is generated when interconnection frequency is lower than FTL-Low for 5-minutes or more. The FTL-Low is 59.950 Hz for Eastern Interconnection and 59.856 Hz for Western Interconnection. FAL, as referenced on this chart, refers to the Frequency Emergency Threshold, where, once reached, system reliability quickly deteriorates. The FAL-Low is 59.908 Hz for Eastern Interconnection and 59.80 Hz for Western Interconnection.

An FTL-High alarm is generated when interconnection frequency is higher than FTL-High for 5-minutes or more. The FTL-High is set at 60.050 Hz and 60.144 Hz for Eastern and Western Interconnection respectively. The FAL-High is set at 60.092 Hz and 60.20 Hz for Eastern and Western Interconnection."

OK... that's pretty precise.

**cradeldorf** · June 26th, 2011, 04:51 PM

I agree...those tolerances are pretty tight.

**Altec Best** · June 26th, 2011, 05:23 PM

Well it seems here in the East we will have the biggest effect.

**Panomaniac** · June 26th, 2011, 06:25 PM

I always new those folks out west lived in a looser time frame. Now we have proof.

**bfish** · June 26th, 2011, 08:58 PM

Our current policy for grid frequency includes both manual and automated correction to keep (some) clocks ~accurate;

"Regulation of power system frequency for timekeeping accuracy was not commonplace until after 1926 and the invention of the electric clock driven by a synchronous motor (a Hammond invention). Network operators will regulate the daily average frequency so that clocks stay within a few seconds of correct time. In practice the nominal frequency is raised or lowered by a specific percentage to maintain synchronization. Over the course of a day, the average frequency is maintained at the nominal value within a few hundred parts per million. In North America, whenever the error exceeds 10 seconds for the east, 3 seconds for Texas, or 2 seconds for the west, a correction of ?0.02 Hz (0.033%) is applied. Time error corrections start and end either on the hour or on the half hour."

What isn't clear is the intent of the "experiment". If they merely discontinue the time correction efforts (which could be a sizable savings alone), the only noticeable effect will be to some of our clocks. If they loosen the overall tolerance standards, that could be a different story.