Zest helps farmers find good ‘ground’
June 2019
Electrical Power & Protection
According to Zest WEG Group, there are misconceptions around what constitutes ‘earth’ and ‘neutral’ connections, and not understanding the differences can create serious problems when connections are made from onsite transformers or other sources. This more often than not leads to earth leakage systems underperforming 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 protection switch.
Experience has shown that many farmers use the neutral connection as the earth when they do an electrical installation, which 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 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 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.
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