EFFECTS OF VOLTAGE SAGS, SWELL AND OTHER DISTURBANCES ON
ELECTRICAL EQUIPMENT AND THEIR ECONOMIC IMPLICATIONS


  EFFECTS OF VOLTAGE SAGS.pdf (Size: 91.11 KB / Downloads: 7)

ABSTRACT

Poor power quality has come to stay in most parts of the
world. In most part of Africa, especially in Nigeria, it is
almost normal not to have good clean power free from
disturbances. If power equipment and loads could talk or
express feelings, I am sure they would have made a big
protest against the great injustices imposed on them. A
survey was carried out amongst 15 multi-national
companies in southwest Nigeria to ascertain the cause(s)
and effects of poor power quality on electrical equipment
and its economic implications.

INTRODUCTION

Most people take the electrical supply for granted and
expect it to be available at the flick of a switch. However,
some businesses like share dealing houses, hospitals and
continuous process lines, are so reliant on electricity that
they have to provide safeguards to ensure that an emergency
supply is always available. Generally, in industry, power
quality is very low on the list of priorities and so very little
attention is given to it, until something goes wrong.
Much of the electrical equipment in an industrial facility
requires high-quality electricity; it will not tolerate sags,
swells, transients, or harmonics, and it certainly will not
tolerate power outages, no matter how short-lived.
Recognizing the limitations of grid-delivered power and the
fact that 80 percent of all power quality and reliability
problems occur inside end-user’s facilities, it behooves all
maintenance and reliability managers to understand the
power quality susceptibilities within their facilities and of
their key equipment.

POWER QUALITY PARAMETERS

Even the best distribution systems are subject to changes in
system voltage from time-to-time. Voltage changes can
range from small voltage fluctuations of short duration to a
complete outage for an extended period of time. The
following industry terms can be used to describe given
voltage conditions.

COST/ECONOMIC IMPLICATIONS OF POOR
POWER QUALITY

Clearly, in a business environment, the equipment in use has
to be resilient to the normal characteristic defects of the
supply and this is not the case with off-the-shelf equipment.
The cost of correction is much lower if corrective action is
taken at the design stage of the equipment but this requires
knowledge of the nature and probability of defects. It is this
knowledge that is missing. This is, however, the most cost
effective approach.
Some equipment makers are recognizing the problem but
the competitive market means that manufacturers will only
respond to customers’ requirements. Until customers
understand the problems and realize that equipment
suppliers can provide a solution, they will not specify
improved performance. The exception is the variable speed
drive market where manufacturers are actively promoting
products with enhanced dip ride through.