PASS M0 - Innovative solutions for distribution substations up to

General descriptionCircuit -breakerThe PASS M0 circuit-breaker is a single pressureinterrupter operating on the well-established selfblastprinciple.The energy for interrupting currents is partlysupplied by the arc itself, thereby reducing theenergy requested from the operating mechanismof about 50% compared with a conventionalpuffer-type circuit-breaker.Combined Disconnector/Earthing SwitchPASS M0 is equipped with a three pole operatedcombined disconnector/earthing switch. Theoperating principle (patented) is based upon therotary motion of the contact which can be closedon the BusBar, earthed or left in the neutralposition.The mechanism is composed of minimal numberof mechanical components and it is intrinsicallyreliable, and maintenance free. This modulardesign can be applied to PASS M0 in SingleBusBar configuration, Double BusBarconfiguration and on all the bushings: BusBar orline sides.All the combinations are possible.In both cases, Single BusBar and Double BusBar,the position of the combined disconnector/earthing switch is clearly indicated at all times byan indicator which is mechanically coupled to theshaft. In addition to this, a visual confirmation ispossible by means of a view port in the enclosure.The disconnector/earthing switch may, in anemergency, be operated manually by means of acrank.Current TransformerPASS M0 is equipped with a conventional currenttransformer, to meet customer requirements, e.g.for retrofitting. Several combinations of cores forprotection and measurements with differentburdens are available. Up to 5 cores can be fittedinto the current transformer.BushingsOverhead lines and BusBars are connected to thePASS M0 by air bushings. The main insulation iscompressed SF6-gas. The insulator consists of anepoxy impregnated fibreglass tube with siliconrubber sheds. The flanges are heatshrunk andglued onto the tube making an extremely strongand gastight joint. The silicon rubber sheds arecast onto the tube and chemically bonded to it,thus allowing no moisture or contamination toenter between them. The silicon rubber sheds arehydrophobic and give very good rain and pollutionperformance. The main features are:Fig. 4The operating mechanism is of the spring type. This typeof drive stores energy in a spring which is dischargedduring operations.• high safety (crack and explosion resistant)• low weight• excellent pollution and rain performance• sandstorm resistant• maintenance free.SF6 Gas SystemThe compact design of the PASS M0 module isdue to the excellent insulation qualities of SF6gas. Its dielectric strength in a homogeneous fieldis about 2.5 times greater than that of air at thesame temperature and pressure. The design of thelive components is such that the field distributionis as homogeneous as possible, which allows theintrinsic strength of the insulating gas to be utilizedmost efficiently.❑ SF6 gas pressures of the PASS M0module at 20 °C• Filling pressure ........................ 680 kPa (abs)• First alarm level ........................ 620 kPa (abs)• Nominal insulation pressure(blocking pressure) ................ 600 kPa (abs)Filling pressure is about 15% higher than thenominal insulation pressure. This guaranteessufficient gas density over a long operationalperiod. To ensure minimum gas loss duringoperation all enclosures, connections and valvesare subjected to severe gas-tightness tests in thefactory.❑ Gas density controlEach PASS M0 pole builds a single gas compartment.Since the dielectric strength of the switchgear andthe breaking capacity of the SF6 circuit-breakerdepend on the density of the SF6 gas, a gas densityrelay is installed to control gas density and detectleakage.4 - PASS M0