Diagnosing and Mitigating Blinks
It is a clear sunny day with not a cloud in the sky… All of a sudden, the room goes dark for a few seconds. Then power returns, joined by the clanging and clunking sound of printers and equipment “rebooting” around the home or office.
So what just happened? Many folks assume that an electrical power surge just happened.
Actually, an automatic circuit recloser (ACR or Recloser) just opened, then “reclosed,” resulting in a momentary interruption of power, also known as a “blink.”
Automatic circuit reclosers quickly respond to problems on an electric utility’s power grid. They are similar to a circuit breaker in your home but different due to their ability to automatically reset themselves to restore power quickly.
Reclosers have been used to protect electric utility systems and customer homes since the 1950s. Few customers even knew about reclosers or blinks until manufacturers started building digital alarm clocks in the late 1970s and early 1980s.
These new digital clocks maintained time by synchronizing with the 60 Hertz frequency of the utility power waveform.
Where digital clocks were found to be quite accurate, early clocks simply did not like “blinks.” When they occurred, the clock would flash 12:00 and require manual resetting—which worked until the lights blinked again.
The incorporation of digital clocks into large appliances and newly introduced microwave ovens further exacerbated the problem of customers getting home to a house full of flashing 12:00s.
What Causes Reclosers to Open and Close?
- A lightning strike somewhere on the utility line that creates an overcurrent condition.
- Cars hitting power poles that can briefly cause the electrical lines to slap together.
- Tree limbs falling into power lines, causing conductors to short out.
- High winds blowing tree limbs and other debris into the power lines.
- Wayward animals attempting to navigate high-voltage lines.
A typical recloser will open and close three or four times before “locking out” due to its inability to clear the line. Once this occurs, a utility service vehicle must be dispatched to investigate and repair the distribution line protected by the locked-out recloser.
So, why do electric utilities continue to use reclosers? Quite simply, reclosers allow for quick restoration of power in a matter of seconds rather than waiting more than an hour for a service truck to troubleshoot a distribution line or replace a blown fuse.
Manufacturers of digital clocks have helped minimize customer complaints by adding internal batteries to keep clocks and appliances working through “blinks.”
Ways to Mitigate Blinks
If a customer calls in and states that they had six or seven “surges,” more than likely they are counting “blinks.” One or two blinks over a three- or four-week period should not be considered excessive unless they recur at a particular time each day or week.
That being said, there are several steps that a utility can take to help reduce the number of blinks a customer may be experiencing. These may include:
- Check alarm clocks and timers for—and replace—their internal backup batteries.
- Ask the customer to document the dates and times that blinks occur. This information can help engineering staff review other events that may have occurred at the same time and assess the number of events reported by the customer.
- Ask the customer to note whether there were high winds, winds from a particular direction, or thunderstorms in the area during the blink.
- Forward the collected information to appropriate engineering staff to help determine the cause and possible solutions. This may include inspecting the line for damaged cross arms, overgrown tree branches, broken insulators, or blown distribution lightning arresters.
- Consider a battery backup for high-value computers and Smart TVs. These can be relatively inexpensive compared with the value of the items being protected.
More than three to five blinks per week could be considered excessive. Customers can help utilities diagnose and reduce or eliminate blinks by carefully documenting each event and observing weather conditions.
The better the documentation, the faster the resolution and mitigation of these events.
Questions?
Please contact Kenick if you have questions about this article or a particular issue you need help with.
Email: Solutions@kenick.com