Metering & Monitoring Systems for Power Reliability and Availability

This article  examines the internal and external factors that can affect electrical supplies, and how metering and monitoring system can support compliance with relevant standards

Power quality is defined as the characteristics of the electrical supply that affect reliability, stability and continuity of service to a system. Reliable power is essential in modern lives, and there is hardly a single industry or market sector that does not require high levels of power quality and reliability.

Power meters
(photo credit: Schneider Electric)

Historically, prior to the advent of solid-state electronics, alternating current (AC) power quality was defined primarily by voltage, frequency and power factor. If these aspects were maintained within industry tolerances, then it would have been reasonable to expect the consumers – domestic, commercial, institutional and industrial – to be suitably supplied with electrical power.
Since the advent of solid-state electronic equipment, however, there has been an increasing need to consider other more complex factors – such as harmonics, transients and momentary disruptions – all of which can result in:

1. Unexpected business downtime

  • Power quality disturbances account for 30-40% of business downtime
  • Poor power quality costs 4% of annual turnover (industry sector)
  • Estimated financial loss of 150bn (£110) per year in Europe

2. Equipment malfunction and damage

  • Overheating of motors, capacitors, cables and transformers
  • Accelerated wear and tear on critical components
  • Improper function
  • Premature ageing
  • Nuisance tripping of circuit breakers
Some 70% of the power quality disturbances originate within the consumer’s premises, while 30% are on the network side.
Some important changes and developments that have occurred in recent years also increase the need for assessment and maintenance of power quality:
  • There is a greater dependence on continuous availability of electric power
  • E-commerce is changing the way all spheres of human activity are interacting with the world
  • Intelligent technology demands power that is free from interruption or disruptions
  • Use of renewable energy has resulted in an increase in power quality issues
  • The level of quality perceived by the supplier (or regulator) may be different from what the customer requires or desires.

This article was extracted from  CIBSE CPD "Module 84: Metering and monitoring systems for power reliability and availability " the full module can be viewed at the below link

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