Momentary Interruptions

To maintain overall system performance, utilities periodically do large grid switching. This switching can possibly introduce momentary voltage interruptions. These are very brief outages, typically less than a cycle in duration.

Most of these disturbances are overshadowed by the utility's distribution system. The interruption hardly exists by the time it gets to most customers. But, for those customers close to substations, or those who have distribution switches at their service entrance, momentary interruptions are important concerns.

The electronic devices in a customer's business will probably withstand short duration interruptions during the change. But the equipment will respond adversely to longer interruptions. The power supplies may not be able to keep the DC voltage perfectly stable, contributing to equipment problems like lock-ups and restarts.

If these anomalies are causing problems, there are two alternatives. First, consider replacing the user's power supplies with ones that have longer ride-through times. This may resolve the problem.

Second, install an energy storage device such as a stand-by power system, called an SPS, or an uninterruptible power system, called a UPS. These devices, if properly specified and installed, will provide the needed ride-through time.