Design & Protection Studies

Plenty of protection studies look correct on paper and fail the first time an engineer tries to apply them. Usually the cause is the same: the model used nameplate assumptions instead of installed plant, the DNO source impedance was estimated, or the grading was checked only at maximum fault level. We build models from actual CT ratios, relay types, curve libraries and cable data, and we grade at both maximum and minimum plant configuration.

Because our engineers also commission, every settings schedule we issue is written to be applied — correct curve nomenclature for the relay platform in use, achievable time multipliers, and settings that respect CT saturation and pilot wire realities rather than idealised curves.

Fault level calculation at each busbar, equipment rating adequacy, protection device coordination through the network including DNO upstream devices, earth fault sensitivity against earthing arrangement, and where required arc flash incident energy with PPE category guidance. Where generation or storage is connected, anti-islanding and G99 interface protection requirements are addressed as part of the same package.

Private HV networks sit behind a DNO device, and their settings are constrained by it. We obtain and work to the network operator's protection policy and upstream settings so the study clears review first time — avoiding the energisation delays that follow a rejected settings submission.