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Controlled switching systems (CSS) have been installed at Notre-Dame 315-120 kV substation located in Montreal in order to improve the power quality during energization of 96 MVArs back-to-back shunt capacitor banks (SCB) on the 120 kV power system. Power quality had to be improved following numerous complaints of particularly sensitive customers. Other alternative solutions were also considered but CSS was found to be the best cost effective solution. Two air blast 120 kV circuit breakers (CB) had to be replaced and one existing gang-operated SF6 CB was modified in order to achieve effective controlled switching operations. Special tests had to be performed on the circuit breaker to prove its suitability for this particular application. Tests were performed according to CIGRE guidelines given in ELECTRA, No. 197, April 2001 and IEC 62271-100.