SIS Solid Insulation System

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Allyson Underwood
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1 SIS Solid Insulation System Quality Security Progress

2 Mühlberg 1 D Oberaurach-Kirchaich Germany Phone: +49 (0) 9549 / 89-0 Fax: +49 (0) 9549 / info@mwb-messwandler.de Parents companies: Wandler- und Transformatoren-Werk Wirges GmbH PO Box D Wirges, Germany WIRGES Phone: +49 (0) 2602 / Fax: +49 (0) 2602 / Ritz Messwandler Ritz Instrument Transformers PO Box D Hamburg, Germany Phone: +49 (0) 40 / Fax: +49 (0) 40 /

3 Contents General 4 Busbar design principle 4 Complex connections 5 Busbar fixing 6 Dimensioning / Conductor material 7 Busbar connection 8 Earthing 8 Outdoor application 8 Quality assurance 9 Tests 9 Ordering information 9

General Especially for the transmission of higher currents the solid insulation system for busbars is an alternative to parallel-connected cables and metal-enclosed busbar connections.

The following inherent benefits speak for the use of fully insulated busbars: Compact design, little space requirements Small bending radii High thermal and dynamic short circuit current withstand

4 General Especially for the transmission of higher currents the solid insulation system for busbars is an alternative to parallel-connected cables and metal-enclosed busbar connections. All requirements with respect to protection of personnel and equipment are met. The following inherent benefits speak for the use of fully insulated busbars: Compact design, little space requirements Small bending radii High thermal and dynamic short circuit current withstand capabilities Safety to touch No maintenance Easy installation Minimum project work for the user No short-circuits between phases due to full insulation Busbar design principle The busbar insulation is built up with Resin Impregnated Paper (RIP). Crepe paper is wound around the conductor (copper or aluminium) and impregnated under vacuum with epoxy resin. This results in a void free insulation, which is partial discharge free. To avoid partial discharge by delamination of the insulation from the conductor a conducting layer is wrapped around the conductor. Layers of insulating crepe paper are built up on the high voltage layer according to the rated voltage. In this insulation layers of semi conducting paper are included for the capacitive grading at the ends of the busbar. These are dimensioned to reach an optimised electric field distribution on the surface of the busbar. Thus a minimised grading length can be reached. Over the whole length of the busbar, except the grading region, an earth layer is wound on the insulating layers. This earth layer is built up by semi conducting paper, aluminium foil layers and axial copper strips to reach a high short circuit current capability. A connection device is soldered on the copper strips used as earthing point of the busbar. As protection of the earth layers additional protecting layers are added. The whole busbar is sealed vacuum tight with shrinking sleeve. After drying the insulation, the paper is impregnated with a low viscosity epoxy resin under vacuum conditions. This manufacturing technology of MWB permits to build a busbar with any geometrical shape. Umax min. length of grading Insulation wrapping (Is) (s) 12 kv 175 mm 10,0 mm 24 kv 215 mm 12,5 mm 36 kv 330 mm 17,5 mm Busbar design principle 1. Conductor 2. Epoxy-impregnated paper wrapping 3. Earth layer 4. Capacitive grading 5. Metal ring 4

Complex connections The length of single busbars is limited by the manufacturing process, transportation and installation conditions. For complex installations the busbars have to be connected.

These joints are fully insulated by connection sleeves, which cover the capactive grading at the busbar ends.

5 Complex connections The length of single busbars is limited by the manufacturing process, transportation and installation conditions. For complex installations the busbars have to be connected. The connection is performed with flexible connectors between the busbars to allow thermal expansion and to compensate tolerances at the installation. These joints are fully insulated by connection sleeves, which cover the capactive grading at the busbar ends. These connecting sleeves are also fully insulated and guarantee an absolute touch safety over the whole length of the busbar installation. For voltages above 12 kv the sleeves are also capacitive gradings. The high voltage connection to the sleeve is realised by a contact spring installed on the flat connector of the busbar. The connecting sleeves have a protection grade IP 45. On demand higher protection grades are available. Busbar connection 1. Insulated busbar 2. Insulated connection sleeve 3. Brass tube 4. Contact spring 5. Expansion joint 6. Earthing clamp 7. Fixing clamp 5

6 Busbar fixing The busbar-fixing elements include aluminium C-profiles, angles, screws and fixing clamps. The fixing elements are movable with respect to each other in any direction and thus allow to compensate for building tolerances. The fixing clamps include fixed bearings and movable bearings, allowing the busbar to move axially within the fixing clamps in case of thermal expansion. In the first instance, the short-circuit withstand capability of the equipment must be considered for the the busbar fixing. Another criterion is the natural frequency of the busbar. The distance between fixing points must be chosen to avoid resonance with respect to the power frequency of the system and its harmonics. A respective computer programme is available, which includes Busbar diameter Distance between phases Mass Bending strength The distance between fixing points of the busbar is computed for each order. Section A-B Busbar fixing 1. Plastic fixing clamps 2. Aluminium double-c-profile 3. Aluminium fixing angles 6

7 Dimensioning / Conductor material The busbar conductors are dimensioned according to DIN 43670/671. The following criteria are taken into consideration: Thermal conductivity of the insulation Heat transmission beween the insulation and ambient air (by convection and radiation) Natural cooling Skin effect The busbars are dimensioned for an ambient temperature of 35 C with a maximum temperature rise of the conductor of 50 C. Accordingly, the maximum temperature of the conductor is 85 C under natural cooling conditions. Deviations from the above dimensioning criteria shall be specified and can be considered when the design calculation is made. The conductor material can be copper (E-Cu) or aluminium (E-Al-MgSi 0,5). Dimensions for conductor material E-Al-MgSi 0,5 U (max) 12 24kV 12kV 17,5 24kV 36kV IN ø Conductor (mm) ø Busbar (mm) ø Busbar (mm) ø Conductor (mm) ø Busbar (mm) 1250 A A A / A 80/ / A 100/ / A 120/ / A 150/ / A 200/ Dimensions for conductor material E-Cu U (max) 12 24kV 12kV 17,5 24kV 36kV IN ø Conductor (mm) ø Busbar (mm) ø Busbar (mm) ø Conductor (mm) ø Busbar (mm) 1250 A A A A 70/ / A 90/ / A 110/ / A 140/ / A 180/ / Other voltages and currents on request. 7

Bubar connection There are several variants of rigid or flexible connections between busbar segments or between the busbar and other equipment parts, viz.

In case the insulated busbar shall be connected gas-tight to an SF 6 -insulated switchgear, a metal flange is fitted at the earthed portion of the busbar.

8 Bubar connection There are several variants of rigid or flexible connections between busbar segments or between the busbar and other equipment parts, viz.: Conductor end with flat terminal according to DIN or according to customer s specification. Conductor end with round bolt and connection by means of terminals. In case the insulated busbar shall be connected gas-tight to an SF 6 -insulated switchgear, a metal flange is fitted at the earthed portion of the busbar. Current connection can be made in an economical way by means of contact bolts or according to customer requirements. Earthing In general a separate earthing connection dimensioned according to the required short circuit current has to be installed in parallel to the busbar system. Every single busbar, connection sleeve and metallic fixation material has to be earthed on this earthing connection. If a busbar or a sleeve is not earthed correctly these elements will be destroyed after a certain time. Outdoor application For outdoor use, the previously described busbar is covered with a stainless steel tube which is proof for outdoor application. To increase the creepage distance, the capactive grading of the busbar insulation is covered on the outside by cast-on sheds. Resin cone Flange Earthing screw Paper resin insulation 1. Contact bolt 2. Conductor 3. Insulation 4. Metal flange Contact bolt Spring Conductor Connection of busbar to a GIS Special design according to customer requirements 8

Quality assurance Before use in production, the material is subjected to the following tests: a) Material conductors and capacitive grading layers: Measurement of specific resistance b) Insulating

9 Quality assurance Before use in production, the material is subjected to the following tests: a) Material conductors and capacitive grading layers: Measurement of specific resistance b) Insulating paper: Verification of purity Test for tearing strength c) Impregnating resin: Measurement of viscosity Measurement of viscosity rise (with temperature as parameter) Measurement of gelation time The impregnating process is checked by the following measurements: Conditioning (degassing) of the resin compound Temperature in vacuum oven Continuous control of evacuation Gelation temperature / time Post-curing temperature / time All completed busbar segments are subjected to the routine tests described on this page. In the development stage, general investigations have been made and the following were determined: Temperature of deflection underload (Martens method) Flexural strength Deflection Impact strength Module of elasticity Coeffitient of thermal expansion Thermal conductivity Tests Each busbar and each connection sleeve are subjected to electrical routine test, viz.: One-minute power frequency test, 50 Hz according to current standards (IEC, VDE, etc.) Measurement of partial discharges Measurement of capacitance and loss factor Visual inspection The following type tests have been made: Power-frequency test and measurement of partial discharges Impulse voltage test Power-frequency test and measurement of partial discharges (rep.) Temperature rise test Temperature cycle test Power-frequency test and measurement of partial discharges (rep.) Life test Ordering information Customers are kindly requested to supply the following information in their orders for quick processing in the works: Rated voltage U n Rated current I n Short-circuit currents I th / I dyn Frequency f Max. ambient temperature Dimensions of busbar Distance between phases Type of connection Available earthing facilities Possible fixing method Conductor material (aluminium or copper) Also, a differential thermal analysis (DTA) and life test were made. 9

10 Shrinking sleeve Detail X Shrinking sleeve Section A-B View in direction of arrow Y Custom-made busbar connection 10

11 Quality Since 1976 an internal QS-handbook (QS stands for quality standards), guarantees a solid product quality. An interactive EDP-system guarantees the impeccable processing of incoming orders from manufacturing to delivery point. Security The produced equipment plays an important part of energy manufacture and energy distribution. Therefore, highest demands are made with respect to industrial safety. By constantly supervising the manufacturing process as well as the current modification of the utilized materials, the highest degree of safety is guaranteed. The available test equipment allows all necessary type and routine tests. Progress A team of qualified engineers with world-wide experience develops, supervises and controls your order.

Location SIS 05/05-1000 DM-SERVICE +49 (0) 61 06 / 87 95-0 In autumn, the Steigerwald with its extended forest of hardwood trees shows its

The old Town Hall ( Alte Rathaus ) in 1000-year-old Bamberg, lies like a ship in the waters of the Regnitz.

12 Location SIS 05/ DM-SERVICE +49 (0) / In autumn, the Steigerwald with its extended forest of hardwood trees shows its best side. Kirchaich is located approx. 20 km west of Bamberg in the lovely picturesque scenery of the Steigerwald. The old Town Hall ( Alte Rathaus ) in 1000-year-old Bamberg, lies like a ship in the waters of the Regnitz. MWB MESSWANDLER GMBH MWB MESSWANDLER GMBH Phone: +49 (0) 9549 / 89-0 Mühlberg 1 Fax: +49 (0) 9549 / D Oberaurach-Kirchaich Germany info@mwb-messwandler.de Quality Security Progress

Brugg Cables High Voltage Accessories. Swiss solutions for independent applications.

Brugg Cables High Voltage Accessories. Swiss solutions for independent applications. Fact Book High Voltage Accessories Brugg Cables Business Unit High Voltage Accessories Dr. Ruben Vogelsang Head of Product