Keeping Time Current

Just as watches sometimes run fast or slow and must be adjusted, older electric clocks use the electrical current’s frequency to stay accurate. To make this work, the electric grid’s frequency must be regularly corrected for “time errors”—in essence, steps taken at power plants help older electric clocks tick properly.

However, in mid-July, the North American Electric Reliability Corporation (NERC), the nation’s power grid watchdog, started a year-long field test to discover if Time Error Corrections (TECs), which have been performed since 1930, actually hurt electric system reliability.

To keep electricity flowing smoothly, we must maintain a stable frequency level which generates electricity for members of Access Energy Cooperative.

The electric grid runs in something called cycles, or Hertz (Hz)—60 cycles per second. That standard is used to match the 60 seconds per minute that keeps time. Older electric clocks depend on that standard to remain accurate. Newer clocks have chips and other electronics in them that stay accurate independent of the 60-Hz standard. 

To adjust for fast time errors, the frequency is lowered slightly from 60 Hz to 59.98 Hz. The concern is that during a time adjustment, which can take several hours, the frequency is already below normal. If a problem during that time drives frequency levels even lower, it could trigger emergency load-shedding measures.

The NERC field trial will suspend time corrections in favor of stabilizing the grid’s frequency. As a side effect, older alarm clocks and some appliance clocks may lose track of time a few seconds a day. By July 2012, it’s possible an affected clock could run up to 20 minutes fast in the East unless the owner corrects the time manually. Since the electric grid operates in three sections, other areas of the country may see a different impact. Clocks in the west may only run up to 8 minutes fast, while clocks in Texas won’t run more than 2 minutes over. Members can check the official time at www.time.gov.

Since most newer appliances and clocks no longer rely on electric current to keep time, it’s unclear how or if the experiment will impact members.

NERC has a plan in place to resume TEC if a reliability issue develops. Access Energy Cooperative will continue to monitor the trial closely.

Source: Megan McKoy-Noe, NRECA