Siemens AG Power Transmission and Distribution Medium Voltage Division Mozartstr. 31c Erlangen Germany.

Transcription

1 Siemens AG Power Transmission and Distribution Medium Voltage Division Mozartstr. 31c Erlangen Germany For questions on power transmission and distribution, please contact our Customer Support Center, hours a day. Tel.: / Fax: / 5 71 (Subject to charge: e.g. 12 ct/min) support.energy@siemens.com Subject to change without prior notice Order no. E50001-U229-A282-X-7600 Printed in Germany Dispo GB The information in this document contains general descriptions of the technical features, which may not always be available. An obligation to provide the respective performance feature shall exist only if expressly agreed in the terms of contract.

2 We are ready: IEC The new switchgear standard Power Transmission and Distribution

3 Standards for all Switchgear are important nodal points in modern power distribution. Correspondingly important is their reliable functioning, a clearly defined switching behavior according to specified parameters as well as the protection of personnel and protection against operational interruptions when an overload occurs. The International Electrotechnical Commission (IEC) has taken up the task of developing the required specifications, their worldwide standardization and further development. The same applies to IEC the new standard for medium-voltage switchgear. As one of the first manufacturers, Siemens has implemented these requirements and already offers the complete product range of air-insulated and gas-insulated switchgear today, type-tested according to IEC IEC IEC

4 Retrospective IEC for four decades this abbreviation was the decisive factor for the type testing of metal-enclosed switchgear. In the meantime there are tens of thousands of switchgear panels of the primary and secondary distribution level based on this standard in use certified according to the mandatory part of the standard and, if required, according to optional tests. The passing of the following tests was obligatory in order to identify switchgear as type-tested: Dielectric test to verify the insulation level of the switchgear (tests with rated lightning impulse withstand voltage and rated short-duration power frequency withstand voltage with the specified values depending on the respective rated voltage). Temperature rise tests to verify the current carrying capacity with rated normal currents. Peak and short-time withstand current tests to verify the dynamic and thermal current carrying capacity of the main and earth circuits; the tests are performed with rated peak short-circuit current or rated short-circuit making current or rated shorttime current or rated short-circuit breaking current. Switching capacity test to verify the making/breaking capacity of the installed switchgear. Mechanical function test to verify the mechanical functions and interlocks. Degree of protection tests to verify the protection against electric shock and foreign objects. Pressure and strength tests to verify the gas tightness and pressure resistance for gas-filled switchgear. There is also the possibility of voluntarily certifying switchgear for resistance to internal arc faults and for personal protection. Manufacturers and operators can select the criteria which are relevant to them from the following six criteria and have them tested. Criterion 1: Doors and covers must not open. Criterion 2: Parts of the switchgear must not fly off. Criterion 3: Holes must not develop in the external parts of the enclosure. Criterion 4: Vertical indicators must not ignite. Criterion 5: Horizontal indicators must not ignite. Criterion 6: Earth connections must remain effective. In order to guarantee safe access to the individual switchgear components, e.g.the incoming cable, without isolating the busbar, the IEC standard differentiates between three types of compartmentalization that serve exclusively as protection against electric shock. Metal-clad switchgear: Division of the switchgear panel into four compartments (busbar compartment, switching-device compartment, connection compartment and low-voltage compartment); partitions between the compartments made of sheet steel, front plate made of sheet steel or insulating material. Compartmented switchgear: Division of the switchgear panel same as for metal-clad switchgear, but with the partitions between the individual compartments made of insulating material. Cubicle-type switchgear: All other types of construction that do not meet the above features of the metal-clad or compartmented designs. In this context, access to the then common minimum-oil-content circuit-breakers for maintenance work without longer operational interruptions was of prime importance because of the limited number of operating cycles. Therefore, with switchgear in metalclad or compartmented design, the busbar in the busbar compartment and the incoming cable in the connection compartment could remain in operation. With a cubicletype design, the incoming cable had to be isolated, but the busbar itself could remain in operation. 3

5 New specifications new challenges Overview of IEC Although the old IEC standard was very helpful, in time it was superseded by the technological progress. Above all, the appearance of maintenance-free vacuum circuit-breakers, with operating cycles far exceeding the normal number, made frequent access to this circuit-breaker no longer of prime importance. The vacuum arc-quenching principle is technologically so superior to other arc-quenching principles that the circuit-breaker can be fixed-mounted again. This resulted in the first-time use of gas insulation with the important features of climatic independence, compactness and maintenance-free design. However, both technologies the vacuum arc-quenching principle and gas insulation were not adequately taken into account in the existing standard. Therefore, at the end of the nineties, the responsible IEC committees decided on the reformulation of the switchgear standard, which finally came into effect as IEC in November 03. At the same time the old IEC standard was withdrawn without any transition period. Four key features are of special note with the new IEC standard: 1. Changed dielectric requirements According to IEC 60298, two disruptive discharges were permitted in a series of 15 voltage impulses for the test with rated lightning impulse withstand voltage. According to the new standard, the series must be extended by another five voltage impulses if a disruptive discharge has occurred during the first 15 impulses. This can lead to a maximum of voltage impulses, whereas the maximum number of permissible disruptive discharges is still two. 2. Increased demands on the circuitbreaker and earthing switch In contrast to the previous standard, the switching capacity test of both switching devices is no longer carried out as a pure device test. Instead, it is now mandatory to carry out the test in the corresponding switchgear panel. The switching capacity may get a negative influence from the different arrangement of the switchgear with contact arms, moving contacts, conductor bars, etc. For this reason, the test duties T100s and T100a from the IEC standard are stipulated for the test of the circuitbreaker inside the switchgear panel. 3. New partition classification The new partition classes PM (partitions metallic = partitions and shutters made of metal) or PI (partitions nonmetallic = partitions and shutters made of insulating material) now apply with respect to the protection against electric shock during access to the individual components. The assignment is no longer according to the constructional description (metalclad, compartmented or cubicle-type design), but according to operator-related criteria (Tables 1 and 2). 4. Stricter internal arc classification Significantly stricter changes have also been implemented here. The energy flow direction of the arc supply, the maximum number of permissible panels with the test in the end panel and the dependency of the ceiling height on the respective panel height have been redefined. In addition, the five following new criteria must always be completely fulfilled (no exceptions are permitted): 1) Covers and doors remain closed. Limited deformations are accepted. 2) No fragmentation of the enclosure, no projection of small parts above 60 g weight. 3) No holes in the accessible sides up to a height of 2 meters. 4) Horizontal and vertical indicators do not ignite due to the effect of hot gases. 5) The enclosure remains connected to its earthing parts. For the internal arc classification of substations with and without control aisle, the testing of the substation with installed switchgear is mandatory in the new IEC standard. The classification of the substation is only valid in combination with the switchgear used for the test. The classification cannot be transferred to a combination with another switchgear type as each switchgear behaves differently in the case of an internal arc (pressure relief equipment with different cross-sections and pickup pressures, different arcing conditions because of different conductor geometries). 4

6 Table 1 Loss of service continuity category When an accessible compartment of the switchgear is opened: Constructional design LSC 1 then the busbar and therefore the complete switchgear must be isolated. No partitions within the panel, no panel partition walls to adjacent panels. LSC 2 LSC 2A then the incoming cable must be isolated. The busbar and the adjacent switchgear panels can remain in operation. LSC 2B Type of accessibility to a compartment Interlock-based Table 2 then the incoming cable, the busbar and the adjacent switchgear panels can remain in operation. Access features Opening for normal operation and maintenance, e.g. fuse replacement. Panel partition walls and isolating distance with compartmentalization to the busbar. Panel partition walls and isolating distance with compartmentalization to the busbar and to the cable. Access is controlled by the construction of the switchgear, i.e. integrated interlocks prevent impermissible opening. Overview of the characteristic values The IAC classification describes a successful test. It results from the definition of the degree of accessibility, the possibilities of arrangement inside a room, as well as the test current and test time (Table 3). Medium-voltage switchgear in the primary and secondary distribution level is generally classified with degree of accessibility A. This means they are intended for use in rooms that are only accessible to authorized personnel (closed electrical service locations). Switchgear that is accessible by general public has the degree of accessibility B (distance of indicators = 100 mm) and polemounted switchgear has the degree of accessibility C (indicators below a tower in an area of 3 x 3 m). Procedure-based Opening for normal operation and maintenance, e.g. fuse replacement. Access control via a suitable procedure (work instruction of the operator) combined with a locking device (lock). Consequences for operators With the new IEC standard, the following conditions must be satisfied by the switchgear operators: Tool-based Nonaccessible Opening not for normal operation or maintenance, e.g. cable testing. Access only with tool for opening, special access procedure (instruction of the operator). Opening not possible / not intended for operator, opening can destroy the compartment. This applies generally to the gas-filled compartments of gas-insulated switchgear. As the switchgear is maintenance-free and climate-independent, access is neither required nor possible. Already existing switchgear can still be operated in accordance with IEC However, new switchgear must fulfill the IEC standard in order to avoid any resulting legal disadvantages. A situation which has a number of advantages. For example, the comparison and evaluation of switchgear features is now more transparent. But also from an economic point of view, they are an investment in the future. Table 3 The notation IAC A FLR, I and t contains the abbreviations for the following values: IAC A Internal Arc Classification Distance between the indicators 300 mm, i.e. installation in rooms with access for authorized personnel, closed electrical service location FLR Access from the front (F), from the sides (L = lateral) and from the rear (R) I t Test current = rated short-circuit breaking current (in ka) Internal arc duration (in seconds) 5

7 Air- and gas-insulated switchgear from Siemens in accordance with IEC We are ready to make you ready as well With intensive development work and comprehensive tests, Siemens has already implemented the performance features requested by IEC at an early stage. As one of the first manufacturers, we offer the entire product range of air- and gas-insulated switchgear for medium-voltage applications in primary and secondary distribution systems today type-tested according to the new IEC standard. A greater margin for your safety Not only that: the more stringent requirements of the dielectric type tests have been implemented without exception. All switching capacity tests for the various circuit-breakers and earthing switches were performed in installed condition, i.e. inside the switchgear panel with the associated arrangement of the conducting path, contacts, etc. This means for you as the operator: One hundred percent certainty that this combination of switchgear and switchgear panel functions reliably. All switchgear series were also tested for the internal arc classification in accordance with the new standard. The maximum permissible number of test objects (generally two or three panels) as well as the changed direction of energy flow of the arc supply significantly increased the demands on the switchgear panels. All switchgear certified in accordance with IEC satisfies all five criteria required for the internal arc test without exception. Ready for the future with Siemens With the fulfillment of the new IEC standard, all our switchgear types represent the latest state of development in technology, safety and reliability. Without exception, Siemens switchgear fulfills the internal arc classification as vital proof of the personal safety. Our switchgear therefore also meets the requirements of CAPIEL the European association of national switchgear manufacturer associations: This is now a type test and not anymore subject of agreement between manufacturer and user. An investment in the switchgear technology made by Siemens is a profitable investment in the future. With the successfully verified internal arc classification, IAC A FLR up to 50 ka and one second arc duration, our switchgear offers maximum possible personal protection. Our type-tested series also entirely fulfill the specifications of IEC in all aspects. In addition, they guarantee the highest possible degree of operational reliability and therefore an extremely low failure rate. Siemens medium-voltage switchgear therefore corresponds to the IAC A FLR classification for short-circuit currents up to 50 ka (depending on the system type) and short-circuit times up to one second. 6

8 Overview of Siemens switchgear Distribution level Insulation Design Loss of service continuity Partition class Internal arc classification* Switchgear type Busbar system Voltage (kv) Short-circuit current (ka) 1s 3s Rated current, busbar (A) Rated current, feeder (A) Primary Gasinsulated Extendable LSC 2B (panels without PM IAC A FLR 31,5 ka, 1s NXPLUS C Single 15 31,5 31, LSC 2B (panels without PM IAC A FLR ka, 1s NXPLUS C Double LSC 2B PM IAC A FLR 31,5 ka, 1s NXPLUS Single 40,5 31,5 31, LSC 2B PM IAC A FLR 31,5 ka, 1s NXPLUS Double 36 31,5 31, LSC 2B PM IAC A FL 40 ka, 1s 8DA10 Single 40, LSC 2B PM IAC A FL 40 ka, 1s 8DB10 Double 40, Airinsulated Extendable LSC 2B PM IAC A FLR 40 ka, 1s NXAIR Single LSC 2B PM IAC A FLR 40 ka, 1s NXAIR Double LSC 2B PM IAC A FLR ka, 1s NXAIR M Single LSC 2B PM IAC A FLR ka, 1s NXAIR M Double LSC 2B PM IAC A FLR 50 ka, 1s NXAIR P Single LSC 2B PM IAC A FLR 50 ka, 1s NXAIR P Double LSC 2B PM IAC A FLR 31,5 ka, 1s SIMOPRIME Single 17,5 31,5 31, LSC 2A PM IAC A FLR ka, 1s 8BT1 Single LSC 2B PM IAC A FL 31,5 ka, 1s 8BT2 Single 36 31,5 31, LSC 1 PM IAC A FL 16 ka, 1s 8BT3 Single Secondary Gasinsulated Nonextendable LSC 2B (panels without PM IAC A FL 21 ka, 1s 8DJ10 Single 17,5 LSC 2B (panels without PM IAC A FL 21 ka, 1s 8DJ Single 17,5 Extendable LSC 2B (panels without PM IAC A FLR 21 ka, 1s 8DH10 Single 17, Airinsulated Extendable LSC 2B (panels without PM IAC A FLR ka, 1s SIMOSEC Single 17,5 11, * Maximum possible IAC classification