Sparks Electrical News June 2019

CONTRACTORS’ CORNER

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ZEST WEG GROUP HELPS FARMERS FIND GOOD ‘GROUND’ – ELECTRICALLY

A ccording to Zest WEG Group, there are mis- conceptions around what constitutes ‘earth’ (or ‘ground’) and ‘neutral’ connections and not understanding the differences can create serious problems when connections are made from on-site transformers or other sources. This more often than not leads to earth leakage systems underperform- ing and compromising the safety of the equipment and operators. Johan Breytenbach, transformer sales specialist at Zest WEG Group, says that the neutral connection in an electrical installation is designed to carry current all the time, while the earth connection is only supposed to carry current for a short period to trip

the feeding transformer. Earthing is therefore a vital part of electrical installations to ensure that circuit breakers will trip under fault conditions. Safe and legal installation needs to start with the selection of the right transformer, with a star configuration to allow the connection to the neutral point. Installation by a qualified and experienced technician is then ideal, to ensure optimal performance. The correct earthing or grounding of electrical currents has a number of important benefits apart from the main concern around safety. It protects equipment and appliances from surges in electricity – commonly from lightning strikes or power surges – which bring dangerously high voltages of electricity into the system. Good earthing will ensure that excess electricity will go into the earth, rather than damaging equipment. Zest WEGGroup’s product line-up includes low and high voltage electric motors, vibrator motors, variable speed drives, softstarters, power and distribution transformers, MCCs, containerised substations, mini substations, diesel generator sets, switchgear and co- generation and energy solutions as well as electrical and instrumentation engineering and project management services.

is a conductor that provides a low impedance path to earth so that hazardous voltages do not find their way to the equipment. Under normal conditions, the earth connection does not carry any current. Neutral, on the other hand, is a circuit conductor that normally carries current back to the source. Neutral is usually connected to earth at the main electrical panel or meter, and also at the final step- down transformer of the supply. Neutral is also the connection point in a three-phase power supply to connect cable termination in order to gain single phase power. In a three-phase circuit, neutral is usually shared between all three phases, with the system neutral being connected to the star point on

your protection switch. “Where this is not understood and the installation is not done correctly, the trip system will not work properly. In addition to this, stray currents are created that could cause other problems,” he says. Experience has shown that many farmers use the neutral connection as the earth when they do an electrical installation, and this is not correct. Current carried on a grounding conductor can result in significant or even dangerous voltages on equipment enclosures. For this reason, the installation of grounding conductors and neutral conductors is carefully defined in electrical regulations. In alternating current (ac) electrical wiring, the earth

Enquiries: +27 (0)11 723 6000

KEY PRODUCTS FOR POWER-FACTOR CORRECTION TO CUT ENERGY COSTS P ower-factor correction is a mechanism to reduce operating costs associated with electricity consumption. Some of the key advantages here are reduced kVA charges, im- proved plant efficiency and network voltage, and reduced overloading of cables, switchgear, and transformers. The power factor is simply the ratio of actual power (known as active power) used in a circuit, expressed in kW, to the mains power drawn, ex- pressed in kVA, ElectroMechanica (EM) Product Manager Artur Socha explains. Large industrial, commercial, or retail operations can have maximum demand charges applied to their electricity bill. Improved power factor relates to immediate savings on the demand charges. Even sites that have switched to renewable energy sources such as solar still need to take power fac- tor into account. To determine the estimated savings that can be realised by installing a Power Factor Correction system, Socha reveals that EM recently launched a Power Factor Correction calculator to allow cus- tomers to determine savings if they are being pe- nalised on their electricity bills with a maximum demand charge. The EM Power Factor Correction calculator is available at http://www.em.co.za/site/ pfc/pfc.html.

Enquiries: +27 (0)11 249 5000

SPARKS ELECTRICAL NEWS

JUNE 2019