Electricity + Control December 2015

COVER ARTICLE

Power Quality, Probability and Profitability – Energy Saving the Elspec Way!

FEATURES: •Control systems, automation+ systems engineering • Transformers+ substations • Flowmeasurement

•Hazardous areas+ safety • Energy+ enviroFiciency

Power Quality Implications Estimating the financial losses associated with Power Quality (PQ) disturbances can be complex as there aremany uncertainties involved. Where effective analysis has been conducted these costs have been found to be significantly high compared to the overall cost base of an organisation. How to Spot the Opportunity It is common, widely published knowledge that continuous mining and manufacturing process plants and digital industries are the most vulnerable to power quality related disturbances. Of similar significance is the growing awareness of economic losses that supply related entities i.e. Eskom, IPPs and municipalities have to factor and account for as part of economic sustainability. Network components suffer extra losses, reduced operational efficiency, abnormal tripping, progressive degradation and premature failure because of various PQ anomalies. The long term financial losses as a result of poor power

quality are those that are not commonly and easily quantified i.e. production losses, scrap, inferior product quality, rework, additional labour and maintenance costs, increased and frequent sustaining capital investment etc. So spotting the opportunity is simple, the challenge really lies in quantifying the size of the prize. Probability is defined as the extent to which something is likely to happen or be the case. And the likelihood of the occurrence or event is usually expressed as a percentage (%).This expressed likelihood can also be referred to as a ‘confidence level’ and forms a pivotal aspect of any energy saving project. Burning questions: Elspec has made the linkage between PQ and Probability through several years of research and development of their leading edge PQMeasurement and Solutions technologies.The uncertainty associated with historical burning ques- tions are now answered with confidence with the Elspec tools in hand. • What are the areas or opportunities for energy saving? • How much can I save and what is the payback? • How confident are you that the savings can be achieved?

Profitability The Technical loss considerations in estimating PQ losses and proposing benefit/saving opportunities can only be made possible if PQ is approached in a systematic manner and backed by technologies that can ‘deliver the goods’. Profitability through PQ involves addressing the losses associated with: • Operational losses such as downtime, equipment failures, scrap, rework etc. • Power Bill Demand (kVA) related costs/penalties as a result of poor Power Factor (PF) • Energy (kWh) ‒ the distinctive offering by Impact Energy, brand ambassadors and exclusive agents for the Elspec product and service portfolio

Description of change in supply conditions Savings due to reactive current compensation and Harmonic reduction Transformers • Harmonics reduction • Current reduction

Effect on equipment

The presence of Harmonic current increases the core losses, copper losses and stray-flux losses. These losses consist of ‘no load losses’ and ‘load losses’.

Additional ‘Ohmic losses’ (I 2 R losses) in the line and neutral conductors. The Eddy Current, which is generated due to the relative motion of the electromagnetic field and circulating current in a conductor, is the root cause of Skin Effect. Voltage Harmonics increases dielectric losses in capacitors and reduction of operational lifetime of PFC capacitors. Resonance and possible catastrophic failures of capacitor bank systems. Increased motor currents in individual phases, resulting in heating and copper losses. Other mechanical/electrical issues e.g. torque reductions,

Cables • Current reduction • Harmonics reduction

Capacitors • Current reduction • Harmonics reduction

Enquiries: Impact Energy Tel. 0861 357 732/ 082 325 3574 or email sishal@impactenergy.co.za

Load • Harmonics reduction (Skin Effect) Hysteresis, Negative Sequence Field due to 5 th , 11 th , etc.

cooling fan problems, insulation degradation. Tripping of VSDs during unbalance conditions.

For non-linear loads, voltage variation due to load variations affects power consumption patterns. Through cycle by cycle reactive energy compensation, voltage is increased and more stable. It is possible to tap down transformers and this has a potential energy saving benefit.

Saving due to optimal voltage control

Typical Technical Loss (kWh) Opportunity Considerations.

December ‘15 Electricity+Control

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