Electrical Asset Management
HV Switchgear Enhanced Ratings
Giving network operators a defensible basis to run high-voltage switchgear harder, for longer, when the network needs it.
No published standard tells an operator how far high-voltage switchgear can safely be pushed above its normal rating, or for how long. Threepwood built the guidance and the calculator that provide the justification.
The challenge
No guidance is currently available to temporarily operate high-voltage (HV) switchgear above its normal load current rating. When demand peaks, or a fault pushes load onto neighbouring circuits, operators have no recognised basis for justifying a short-term overload.
No current published national or international standard addresses the problem, so decisions are made conservatively, and flexibility that the network could safely use is left on the table.
There is opportunity to provide guidance and tools that can assist network operators to justify temporary short-term overloading of certain switchgear.
Our approach
Threepwood developed a guidance document, supported by a calculator tool, that lets operators justify temporary overloading situations. Rather than judging switchgear against a single steady-state rating, the method models how equipment temperature responds to a defined loading period.
A short-term overload can then be assessed against the equipment’s thermal limit and its time constant, so the loading a circuit can carry over a fixed window is understood, not guessed.
The outcome
The results
Keeps supplies on
Provides short-term flexibility to maintain supplies when the network is under strain.
Rides through faults
Allows supplies to be maintained following fault outages, where the network may be temporarily overloaded.
Defers capital cost
May assist in deferring asset replacement and the associated costs.
Facing a similar challenge?
Put the same rigour to work on your network
From switchgear ratings to substation design and asset management, we help network operators justify decisions and defer cost. Tell us about your project.
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