The challenge
A utility serving a residential area through a medium-voltage network experienced increasing faults, outages and equipment damage. Existing protection did not isolate faults selectively, affecting more of the network than necessary.
Our approach
- Reviewed single-line diagrams, relay settings, coordination curves and fault history for three substations and three feeders.
- Modelled the network and performed load-flow and short-circuit studies; assessed fault levels ranged from 3.2 kA to 12.0 kA.
- Revised relay settings and reviewed the time-current curves.
- Checked selective operation across fault scenarios, load variation and future expansion.
The outcome
Revised settings were implemented to support selective coordination and faster fault isolation. The reported outcome was shorter outages and less equipment damage, with disconnection limited to the faulted section. Coordination was also checked under the assessed load and expansion scenarios.
What this means for the owner
Protection coordination should address how the network operates today and the changes expected as it grows.
Client: Utility operating a medium-voltage distribution network. This summary reflects the recorded project scope and outcomes. Project references are available subject to client confidentiality.
