Various projects including;

• Benmore 100% stator earth fault protection, work scope and protection relay setting report.  The Benmore generators, were earthed via a single 92.5 W NER which limits each generators’ earth fault contribution to approximately 100 A.  Current-operated earth fault protection had a sensitivity of about 15 % and thus did not provide full, or sensitive coverage for earth faults on the stator winding. Meridian Energy wished to improve this by taking a voltage tapping across the NER, then connecting this to the existing Beckwith M3430 relay via an isolating transformer. Traditional voltage based earth fault protections were then set (in addition to the existing current based earth fault protections), so as to provide 100 % stator earth fault coverage. Earth fault protection function 59N covering the top-portion of the stator were applied (using 50 Hz neutral over-voltage), as was function 27TN covering the bottom-portion of the stator (using 150 Hz neutral under-voltage).

• Complete generation fault studies using Transpower’s Digsilent network model, for 9 power stations. The fault studies included sufficient detail so that the generation company’s protection engineer may complete generator protection sensitivity and co-ordination checks for faults across the generation/transmission asset boundary. This is so that the protection requirements of the Electricity Governance Rules can be checked.   The deliverables were the results of the fault studies, on a per power station basis.
  
• Fault tables.  A document capturing all of Genesis power stations Fault Current Levels.  A summary of fault levels, including both the fault level and the fault contributions.   Shown graphically, by way of a SLD showing the various fault levels and contributions at the different locations, for both phase faults and earth faults
• Earthing Investigation – Earthing Transformer/NER Specification.  An assessment and the calculations/specifications for the replacement earthing transformers and NER’s at Tokaanu Power Station.