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Facility Maintenance Decisions

Preventing Power Predicaments

Technology and maintenance strategies for managers seeking to keep facilities protected against brownouts and blackouts

By Jim Degnan, P.E. Power & Communication   Article Use Policy

Nothing makes one appreciate electricity like a good blast of air conditioning on a hot August afternoon. Yet as summer comes to a boil, the possibility of another round of possible brownouts and blackouts looms over the nation. Most engineering and maintenance managers concur that the best way to appreciate electricity is to remember what happened the last time it wasn’t there.

While institutional and commercial facilities can’t control the grid, they can control their facilities’ preparations for potential power problems. What can managers do to keep the power on? A closer look at the challenges institutional and commercial facilities face — as well as equipment, technology systems, and inspection and testing tips to protect against power problems — can help managers develop a successful strategy.

Utility Considerations

Large, system-wide blackouts are rare, but when they occur, they make headlines. Smaller outages related to equipment failure or storms are far more likely. In either situation, the end result is the same — the facility is without power.

To a large extent, the reliability of a region’s electrical utility depends on the proximity of a facility to metropolitan areas or utility substations. Most major metropolitan area utilities serve their customers with a network, and each facility receives power from one or more substations.

Network protectors can automatically switch a facility’s service from one substation to another. In rural areas, the density of customers is far less, so utilities construct less reliable power systems. A facility might be at the end of an old overhead line, which is susceptible to tree limbs, vehicular accidents and a general lack of attention.

These factors increase the chance of losing power. If the power delivery chain is well constructed and if automated backup switching equipment is in place, the chances of an outage are far smaller.

If loads on a utility’s substation get too high, a facility’s service voltage will decline, creating a situation commonly referred to as a brownout. High loads can be caused by weather-related peak power demands or nearby equipment failures, which can force too many customers onto a single substation.

Brownouts can precipitate facility equipment failures, especially in motors. If motor voltage declines, the motor will try to compensate by drawing more current. Motor heat loss is proportional to the square of the current, and hot motors are prone to failures.

A good starting point for improving power reliability is to talk with the local utility. Expressing concerns to utility representatives about the integrity of aging equipment or the lack of redundancy will help to put the portion of the system that serves a facility on an accelerated capital improvement path. Managers should addressed these points:

  • Ask if automated switching is available to restore power if the line that normally serves a facility fails.
  • If automated switching is not available, find out if the facility can be connected to a different substation through manual switching or sectionalizing.
  • Inquire about the age of the utility’s system and the nature of its construction. If it is an overhead line, ask when the poles, insulators, or power lines were replaced. If the utility has an underground feeder, find out the age of the cable and the type of insulation used. Some insulation, such as ethylene propylene rubber, can last up to 40 years. Others, such as high-molecular-weight, cross-linked polyethylene, begin to fail after 20 years.
  • Ask to see the facility’s service record to determine if the quantity and duration of outages that the facility incurs are higher than normal.

In recent years, many utilities have deferred capital investment while deregulation shakes out the industry. Most institutional and commercial electric accounts are major sources of income for utilities. When owners ask about reliable power, they stand a better chance of receiving it.

Technology Options

Inevitably, there is no guarantee on the availability of utility power, so maintenance and engineering managers must prepare their facilities to meet this challenge. In response, many facilities are investing in emergency generators or uninterruptible power supplies.

This investment might be driven by economic considerations, such as data centers and process related industries, or it might be driven by the need to sustain life found in hospitals. Once emergency power becomes available in a facility, the justifications by users to be on emergency power readily appear.

Emergency generators are common in most large facilities to support life-safety systems. In the event of a fire or power failure, these electrical loads permit occupants to safely exit a building. Life-safety systems must be isolated from other power systems; so a single receptacle cannot be added to a life safety system unless it is dedicated to a life-safety load.

When facilities invest heavily in standby generators, the generation plant can be used to mitigate brownout conditions, as well as blackouts. The utility might offer a cost payback for this service, but facilities might have to comply with local clean air regulations.

Managing building power and emergency power systems is much easier when metering equipment is permanently in place. All manufacturers of major distribution equipment offer individual or integrated power monitoring equipment.

Basic equipment allows users to determine the presence of voltage sags or spare capacity, while advanced equipment can evaluate power quality issues such as transients or harmonics. Sophisticated systems have adjustable alarm thresholds that immediately alert personnel to progressively deteriorating voltage or other power conditions.

 

Maintenance Insights

How can managers help their facilities mitigate the effects of brownouts and blackouts? These suggestions can help ensure backup systems will operate properly when needed:

    Generator testing. Frequent and thorough testing of emergency generators should simulate an outage if the facility process permits. Instead of punching the test button on an automatic transfer switch, throw the main breaker off. If possible, do this during peak use and record those departments that are most adversely affected. In this way, managers become better prepared for an extended outage. No one thinks about the garage door being on emergency power until the power outage closes a facility, and no one can leave to go home.

    If managers expect to maintain operations during an extended outage, test all backup systems accordingly. Testing generators for an hour each month at 5 a.m. might increase the chances of generators starting and coming on line, but a four-hour test in the afternoon during August will reveal latent thermal problems that otherwise might not manifest themselves. If diesel fuel is used, the extended testing will turn over the fuel more frequently, preventing it from aging.

    Technicians should test diesel generators annually for at least 70 percent of their nameplate-rating load to prevent build-up of carbon in the cylinders. If the connected load cannot challenge the generators, consider bringing in a portable load bank.

    Technicians can test generator batteries at the same time generators are tested.

    UPS testing. UPS also should be inspected and tested. While full-load tests might not be possible, partial testing and use of online battery-cell-monitoring systems helps assure that power will be there when it is needed.

    Infrared testing. This photographic technique is extremely useful in identifying hot spots with potential for imminent failure. Best results occur when systems are heavily loaded.

The Best Defense

Managers must take every precaution to protect facilities in the event of an outage. If power fails, the best defense is to know what to expect from the facility and its users. Following are some tips to ensure a smooth response during an outage:

  • Have a written plan that includes ways to contact critical personnel during an outage. If possible, communicate this plan to staff annually.
  • Develop an procedure that documents outage event tracking. This documentation is also a good defense when requesting better service from the utility.
  • Provide staff with easy access to documentation, which can eliminate much of the confusion during an outage.
  • Review the plan’s details. During blackouts, communications are critical. Most users develop issues that require immediate attention from facility support personnel. Does the facility stock adequate spare batteries for radios? Are the public-address and security systems on emergency power?
  • Know where to obtain temporary or replacement components, including transformers, generators and switches.

Maintaining and testing a facility’s power equipment, working with the utility to obtain the most reliable power, and having a plan in place are the best defenses against brownouts and blackouts.


posted on 8/1/2004



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