Incompatibility between MV Switchgear conforming TO the international standards and their use in DNO’s substations M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Distribution network criteria MV switchgear has to meet the following criteria : Network’s real service conditions Network use Load current capacity under high ambient temperature Service continuity M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Network’s real service conditions Substation in the humid countryside without heating Substation in cellar (P) Metallic substation  High temperature  Low temperature  Moisture M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Network use Connection of cable with cross section according to Irswitchgear : Ir = 630 A  Cable section = 630 mm² Al Ir = 800 A  Cable section = 2x400 mm² Al  mechanical stress on the connection during connection work and during temperature rise and short circuit (expansion ) Few operations (except for smart grid application)  higher forces for switching operations M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Load current capacity for high ambient temperature Generally low load current Peak current for some hours in emergency situation M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Service continuity Very high cost of outage Maintenance free Cost of outage due to cable or switchgear failure Cost of operation to liberate the installation Maintenance free M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Modes of ageing Corrosion of metal parts under the influence of humidity and heat Degradation of the insulating parts under the influence of moisture, heat and dielectric stress Tightness of the vessel containing the insulation gas mainly influenced by temperature M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Standards: implemented improvements Example of improvement implemented in the last IEC 62271-200 Stress on interlock mechanism: attempt to operate the switching device in the wrong direction with a prospective force of 750 N M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Standards: examples of needed improvements Normal service conditions IEC 62271-1 should include: Use for network service conditions Consequently define required type tests 60587 Tracking test 62271-304 but with increased number of cycles, HV impuls test and PD measurements 60068-2-11 Salt mist 62271-1 Tightness at 40°C M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Standards: examples of needed improvements Other required type tests Temperature rise test and short circuit test to perform with a representative cable connection Dielectric test on SWG equipped with all accessories ( connection points for cable test) M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Standards: examples of needed improvements Additional design criteria to be taken into account: Possibility to respect EN 50110-1 for maintenance purposes (appropriate interlockings) Required accessories for test purposes arc suppressors are not addressed Active parts outside the enclosure are not addressed M. Arens – Y Tits – Belgium – Session 1 – Paper 0950

Conclusions Need to specify the DNO requirements  discussion and preparation between DNO  more implication of DNO in normative working groups M. Arens – Y Tits – Belgium – Session 1 – Paper 0950