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        • Aurora works across a wide range of traditional power generation systems, from small CHP units up to large industrial power generation facilities. We have extensive experience in considering synchronous generators fault contribution into the network, as well as considering issues such as dynamic response and transient stability of synchronous generators.

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        • Aurora provides a range of services to the Renewables and Battery Energy Storage Systems industries, and can provide advice on analysis on greenfield developments or integration into existing brownfield industrial facilities. We specialise in providing grid simulation and G99 compliance studies to support renewable connections to the UK network, and other European networks.

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        • Aurora works in light and heavy industry providing a range of services to help plant owners analyse and understand their networks, identify weak spots, providing guidance on system loadings, fault levels, earthing, protection coordination and arc flash.

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        • Aurora works in Building Services industry to support multiple M&E contractors in development of the HV aspects of their design, or integration of renewable technologies like roof top solar.  Services include system analysis for fault levels, harmonic analysis, protection coordination and arc flash analysis.

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        • Aurora has extensive experience in the water industry and has worked fs, identify weak spots, providing guidance on system loadings, fault levels, protection coordination, motor starting earthing and arc flash. We also have extensive experience in helping water companies integrating renewalbe power and battery storge technologies into their sites.

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        • Concept selection, contingency analysis, switchgear and transformer specification, SLD preparation, cable sizing, UPS sizing, substation layouts, protection scheme design, wiring modifications for EPC and M&E companies.

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        • Earth potential rise (EPR) calculations and touch and step voltage calculations with either CDEGS or XGSLab, earthing layouts, soil resistivity testing, fall of potential tests, earthing inspections and resistance testing.

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Earthing Studies

Earthing is one of the most complex and poorly understood aspects of power system engineering, with many engineers regarding it as a ‘black art’ or ‘alchemy’. In truth it is not an easy subjective, and one that is not overly intuitive, but there are some key ideas that are worth taking the time to understand. This blog post is only a very brief overview of the main areas of earthing studies, and there will be many more posts too follow on the subject!

One of the key things to first understand is that the HV and LV earthing studies have very different focuses. LV earthing is primarily concerned in providing clear paths for earth fault current to flow in, correctly sizing the conductors to handle the fault current and deciding which earthing strategy to use i.e. TN-S, TN-C-S, TN-C, IT or TT (Wikipedia actually explains them fairly well). In practice, in the UK, most earthing systems are TN-S or TN-C-S, but there are a few important exceptions. This is a complex area, and an incorrect specification can put personnel at risk and lead to nuisance tripping of circuit breakers.

HV earthing is subtler, and much more complex – typically requiring the use of complex modelling packages such as CDEGS. HV earthing is based around is how the system and surrounding area behaves should a phase-earth fault occur, and how the fault current will return to the source. In HV systems the ‘source’ substations are usually far remote, and an earth fault current may need to ‘travel’ many km to reach it. This fault current will flow into the mass of ground the earth rods and if available through cable sheaths and ground wires. In HV systems it is the earth fault current that flows into the ground that is of most concern, as this can create at Earth Potential Rise (EPR) that can adversely affect nearby livestock, personnel and buildings.

An issue important to all earthing studies, is how and where the neutral and earth are bonded together and if neutral earthing resistors or insulation monitors should be used. These decisions are of key importance for the safety, continuity and reliability of the electrical network and a frequent source of confusion amongst even experienced engineers. Due to the complexity of earthing studies and the differences between HV and LV earthing, there will be several dedicated blog posts on each subject later. If you have any questions or would like to know more, please do not hesitate to get in touch.