Charge Development of GIS Spacers
National Grid Electricity System Operator
National Grid TO Innovation Team
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Innovation Funding Incentive
It is known from experience that gas-insulated switchgear
(GIS) substations are susceptible to the effects of charge
trapped on isolated sections after switching. The DC electric
field associated with trapped charge can lead to migration of
charge onto insulator surfaces and a reduction in the
withstand performance. Since the mechanism by which
charge migrates onto the insulators has not been identified, it
is difficult to eliminate the problem at the design stage and,
at present, the effects of trapped charge are managed by
adopting special switching procedures for GIS. The present
work aims to understand migration of charge onto GIS
insulators by applying modern measurement techniques so
that the issue may be eliminated by appropriate design.
The mechanism(s) by which charge accumulates on the surfaces of
solid support insulators in GIS are to be investigated to recognise the
design factors that confer immunity or susceptibility to trapped
charge, to eliminate at identified sites the requirement for special
switching procedures for GIS and to incorporate appropriate clauses
in specifications to eliminate susceptible designs.