Faults within switchgear enclosures, as a result of operating errors or unusual operating conditions, cannot be completely ruled out and may result in an internal arc.
With this in mind, global specialist in energy management, Schneider Electric has introduced GMA switchgear specifically designed to significantly lower the probability of internal arcs during its service life.
“As the IEC 62271-200 standard has confirmed that extraordinary operating conditions or operator errors may give rise to an internal arc, it is important that switchgear provides operators with a very high degree of protection,” says Isaac Kruger, manager: MV offer and technology at Schneider Electric South Africa.
“Operator safety is achieved by reducing the hazard to a tolerable level as the risk stems from both the probability of the occurrence and the severity of the resulting damage. To this end, Schneider Electric has ensured that its GMA switchgear is equipped with all imaginable preventive measures in accordance with SANS IEC 62271-200.”
Measures to reduce the probability of internal arc occurrences have been designed and implemented, including the use of gas-filled compartments to prevent internal arcs.
“Focus was placed upon ensuring maximum protection of people with additional measures to limit the external consequences of internal arcs,” adds Kruger. “These include pressure relief devices and non-operation unless the front is closed. All of these measures have been systematically implemented in the GMA switchgear series.”
Planning engineers and companies are able to refer to the IEC guidelines for the selection of suitable switchgear with regard to internal arcs. Where the risk is negligible, metal-enclosed switchgear with internal arc classification is not required.
“However, it is important that in the case of gas-insulated switchgear the risk of internal arc faults is extremely low by design and if the risk is considered as essential then only metal-enclosed switchgear with internal arc qualification IAC should be used.
“In making this decision, planning engineers and operating companies should take note of ISO/IEC guide 51, section 6. This procedure implies that the operator must contribute to reducing the risk.”