Protection design and studies

In any HV or LV electrical installation, correctly designed back-up protection and discrimination will minimise disruption caused by electrical faults.

To achieve this, proper electrical protection studies may be necessary. The identification of optimum protection settings and, in addition, the correct use of short circuit study result to selectively coordinate time current characteristics of electrical protective devices.

Incorrect protection settings can result in spurious tripping during normal load conditions, or failure to trip when a fault occurs. Inadequate discrimination can result in unnecessary disconnection of supply to loads.

Deliverables

• Perform calculations of the fault currents at all points on the grid with the aim to identify the minimum and maximum values of the current which the protection devices must eliminate
• Analyse the existing protection plan or define a new one
• Conduct a settings and selectivity analysis, involving constructing current-time curves and allowing the selectivity to be verified

Depending on the outcome of the analysis of the existing system, further services may be:

• Validate the protection plan in its current state
• Validate the protection plan by adjusting certain settings of the protection devices
• Revise the protection plan by defining a new protection strategy for the site.