Shunt Capacitors

TEKNISKA RIKTLINJER 2010-12-21 TR1-17ErevB

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ENHET, VERKSAMHETSOMRÅDE VÅR BETECKNING

NT, Nätteknik TR1-17E

DATUM SAMRÅD

2010-12-21 NU, VAB TECHNICAL GUIDELINE

VERSION

B

Shunt Capacitors

Preface These guidelines are based on the international standard IEC 60871-1. The guidelines do state preferred alternatives where the standard allows selections. They also include additions to and clarifications of the standard. The guidelines may as part of a contract be made compulsory for the Supplier and will in such cases specify requirements that will in addition to the standard be applicable for manufacture and testing of high voltage capacitor units. This document has been prepared on behalf of Svenska Kraftnät and Vattenfall Eldistribution AB.

Revision Revision note Date

B Rated voltage explained. Appendix 2 replaced. Alternative solutions for connection discussed. Pollution classes b and d added for insulators. Demande for Geotextile removed.

2010-12-21

TEKNISK RIKTLINJE 2010-12-21 TR1-17E revb

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Innehåll

1 ............................................................................................................... 5 GENERAL

1.1 ................................................................................. 5 Applicable standards

2 ..............................................................................6 OPERATIONAL CONDITIONS

2.1 ....................................................................6 Environmental Temperature

2.2 .....................................................................................................6 Pollution

2.3 ...........................................................................................6 Wind Pressure

3 ..............................................................................................................6 Definitions

4 .............................................................................................................. 7 Rated Data

4.1 ................................................................................. 7 Insulation Test Level

4.2 ......................................................................................... 7 Rated frequency

5 ...........................................................................8 Design of Shunt Capacitor Banks

5.1 .......................................................................................................8 General

5.2 ................................................................................8 Design Requirements

5.3 .......................................................8 Foundations and Support Structures

5.4 .................................................................................8 Corrosion Protection

5.5 ..............................................................................................8 Environment

5.5.1 .......................................................................8 Insulating Liquids

5.6 ..........................................................................................9 Capacitor Units

5.6.1 ...............................................................9 Selection of Rated Data

5.6.2 .....................................................................................9 Balancing

5.6.3 ......................................................................9 Overload Capacity

5.6.4 ............................................................................................9 Fuses

5.6.5 ........................................................................ 10 Fuse-less Design

5.6.6 .................................................................... 10 Discharge resistors

5.6.7 ................................................................................. 10 Containers

5.7 ............................................................................. 10 Current Transformers

5.8 ........................................................................ 10 Current Limiting Reactor


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5.8.1 ........................................................................................ 10 Design

5.9 ..................................................................................................11 Insulators

5.10 ................................................................................................... 12 Earthing

5.11 ................................................................................... 12 Protective Fencing

5.12 .................................................................. 12 Thermovision Measurements

6 ............................................................................... 12 Rating Plates and other Signs

6.1 ..................................................................................................... 12 General

6.2 .................................................................... 12 Capacitor Unit Rating Plate

6.3 ................................................................... 12 Capacitor Rack Rating Plate

6.4 .................................................................. 12 Capacitor Bank Rating Plate

7 ...................................................................................................... 13 Lifting Devices

8 ...................................................................... 13 Spare Parts for the Capacitor Bank

9 .................................................................................................................. 13 Testing

9.1 ................................................................................................ 13 Type Tests

9.2 ........................................................................................... 13 Routine Tests

10 ..................................................................................................... 14 Documentation

10.1 ..................................................................................................... 14 General

10.2 ........................................................ 14 Documentation Included in Tender

10.3 ...................................................... 14 Documentation Included in Delivery

10.4 .................................... 15 Documentation and Spare Parts After Delivery

11 ............................................................................................................... 16 Appendix

11.1 ......................................................... 16 Appendix 1. Design and main data

11.2. Appendix 2 Component Data List ............................................................17


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1 GENERAL

1.1 Applicable standards Applicable Swedish standards (SS) shall be used. When these do not exist, European standards (EN) and international standards (IEC) are applicable. The latest version of each standard shall be used. If equipment does not in all respects fulfil the applicable standard and any additional requirements of this document, the deviations shall be clearly presented. Applicable standards and specifications: SS-EN 60529 Degrees of protection provided by enclosures (IP-code) SS-EN-ISO 1461: 2009 Hot dip galvanized coatings on fabricated iron and steel

articles -- Specifications and test methods SS 3192 Varmförzinkade gängade ståldetaljer SS 14 23 03 Rostfritt stål – SS-stål 2303 SS 421 01 01: 2004 Starkströmsanläggningar med nominell spänning

överstigande 1 kV a.c. SS 421 01 67: 2001 Dimensionering av utomhusställverk – Vind och islaster SS-IEC 60168: 2001 Tests on indoor and outdoor post insulators of ceramic

material or glass for systems with nominal voltages greater than 1000 V.

SS-IEC 60273: 1993 Characteristics of indoor and outdoor post insulators for systems with nominal voltages greater than 1000 V

SS-EN 60437: 1997 Radio interference test on high-voltage insulators SS-IEC 62231: 2007 Composite station post insulators for substations with a.c.

voltages greater than 1 000 V up to 245 kV - Definitions, test methods and acceptance criteria

IEC 60060-1: 1989 High voltage test techniques – Part 1: General definitions and test requirements

IEC 60071-1: 2006 Insulation co-ordination – Part 1: Definitions, principles and rules

IEC 60071-2: 1996 Insulation co-ordination – Part 2: Application guide IEC 60099 all parts Surge arresters IEC 60549: 1976 High-voltage fuses for the external protection of shunt

power capacitors IEC 60815: all parts Guide for the selection of insulators in respect of polluted

conditions IEC 60871-1: 2005 Shunt capacitors for a.c. power systems having a rated

voltage above 1000V IEC 60871-2: 1999 Shunt capacitors for a.c. power systems having a rated

voltage above 1 000 V – Part 2: Endurance testing IEC 60871-3: 1996 Shunt capacitors for a.c. power systems having a rated

voltage above 1 000 V – Part 3: Protection of shunt capacitors and shunt capacitor banks

IEC 60871-4: 1996 Shunt capacitors for a.c. power systems having a rated voltage above 1 000 V – Part 4: Internal fuses

The following guidelines and recommendations are applicable:


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TR2 Svenska Kraftnäts Riktlinje för kontrollanläggningar TR1-02 Cable Current Transformers 7.2 – 420 kV TR1-04 Self-contained Current Transformers 7.2 – 420 kV TR1-13 Svenska Kraftnäts Riktlinje för miljö TR1-16 Svenska Kraftnäts Riktlinje för skyltar I ställverk VAST-Vattenfall Jordningsanvisningar, ställverk, 1987 EBR KJ 60:4 Stängsel för kraftanläggningar

2 OPERATIONAL CONDITIONS

2.1 Environmental Temperature The supplier shall indicate the conditions under which the capacitor units can be installed and what temperature interval is applicable. The capacitors shall be classified in categories of allowed temperatures according to IEC 60871-1, where each category is specified by a number, followed by a letter. The number indicates the lowest ambient temperature under which the capacitor may be in operation. The letter indicates the upper limit of the temperature interval. Capacitors for indoor installations shall normally be classified –25/A. If installed in a normally heated room, category –5/A may be used. For outdoor installations in southern and central Sweden, class –40/A is applicable. Outdoor installations in northern Sweden (north of Dalälven) requires class – 50/A.

2.2 Pollution Special requirements for corrosion protection, creepage distances and possibilities for spray-washing insulators are applicable for installations in polluted or coastal areas. See also 5.4 and 5.9.

2.3 Wind Pressure For normal outdoor installations, a wind pressure of 700 Pa on a cylindrical surface shall be used. This corresponds to a wind velocity of 34 m/s. In case equipment is installed on heights or in coastal areas a higher wind pressure might be required, in which case load calculations shall be made using wind pressures according to SS 421 01 67.

3 Definitions

In general, definitions are found in the applicable standards. Rated voltage The rated voltage is the upper limit of the system voltage for which the device is intended. (Same as the highest voltage for equipment) Rated value


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A quantity value assigned, generally by a manufacturer, for a specified operating condition of a component, device or equipment. (IEV 151-04-03) Nominal voltage A suitable approximate value of voltage used to identify a system or device. (IEV 601-01-21) Highest voltage for equipment The highest r.m.s. phase-to-phase voltage for which the equipment is designed in respect to insulation as well as other characteristics which relate to this voltage in the relevant equipment standards. (IEV 604-03-01)

4 Rated Data

4.1 Insulation Test Level The following selection of standard insulation test levels are used:

Highest voltage for equipment

(kVrms)

Rated lightning impulse test level (kVpeak)

Rated power frequency test level (kVrms)

12 75 28 24 125 50 36 170 70 52 250 95

82,5 *) 380 150 145 650 275 170 650 275 245 950 395

*) Not standardised by IEC

Rated switching impulse test level (kVpeak)

Highest voltage for equipment

(kVrms)

Rated lightning impulse test level

(kVpeak) Phase-Earth Phase-

phase

Rated power frequency test level (kVrms)

420 1425 1050 1575 520 A Shunt capacitor Bank shall have the same rated voltage as highest voltage for equipment. In some cases the Capacity is defined for an other voltage as Nominal voltage. In the documentation the Capacity may be given both for this voltage and highest voltage for equipment. At the Rating Plate, the capacity at highest voltage for equipment shall be given.

4.2 Rated frequency The rated frequency shall be 50 Hz.


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5 Design of Shunt Capacitor Banks

5.1 General All components, which are required in order to fulfil the required function of the capacitor bank, shall be included in the delivery. This includes capacitor units, racks, post insulators as required, fuses, current transformers for unbalance protection, tubes / stranded conductors for high voltage connections and interconnection of the units to a completed bank. Main technical data for a specific delivery are given in Appendix 1.

5.2 Design Requirements The capacitor units shall be connected in parallel and serial groups in order to meet the specified type and capacity of the complete bank. The racks and support insulators, as well as interconnections, shall be designed to allow replacement of individual cans. All post insulators with the same rated voltage, shall have such physical dimensions that they may be interchanged with each other, without requiring any special adaptors or moving of capacitor units.

5.3 Foundations and Support Structures Capacitor banks and current-limiting reactors shall be placed on support insulators with supports bolted to concrete foundations. Design requirements and applicable standards for steel supports and concrete foundations are listed in Item 1 above.

5.4 Corrosion Protection All external details shall be made of corrosion resistant material. Steelwork shall be either stainless or be protected by hot dib galvanizing (SS-EN ISO 1461). If the capacitor bank is to be installed in a corrosive atmosphere, an additional corrosion protection might be required. This will be stated in Appendix 1 in such a case.

5.5 Environment Environmentally harmful chemicals shall be replaced by less harmful ones where this is possible (substitution). Scientific hesitance shall not prevent actions when there is a risk of serious harm to the environment.

5.5.1 Insulating Liquids Insulating liquids are used in current and voltage transformers as well as in capacitor units. As insulating liquid, mineral or synthetic oils such as Faradol or Edisol shall be used. The insulating liquid must not include any PCB. Spread of oil on surface or leakage into earth shall be avoided by providing a protective covering of the geotextile type over a large enough area beneath the bank. The proposed size of the covering shall be shown in the tender. As the volume of each container is small, the risk of significant leakage is small.


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The chemical properties of the insulating oil must be such that it is biologically degradable and that the toxicological levels are minimal in case of leakage. Complete chemical and environmental data shall be submitted with the tender.

5.6 Capacitor Units

5.6.1 Selection of Rated Data Voltage and capacity (stated in kVAr), as well as the number of units in parallel and series groups shall be selected correctly in order to achieve the specified ratings of the bank. Furthermore, the physical placement and ratings of units in series and parallel be selected so that no healthy unit will be subjected to a voltage increase above 10% in case any one fuse has tripped. This shall also be applicable to windings of e.g. reactors in case included in the bank.

5.6.2 Balancing The placement of the included capacitor units shall, considering the variation of rated data between individual units, be made with care and in such a way that over-voltages over units are avoided. The allocation of units shall be supported by documentation showing:

Serial number and measured capacitance of all units Physical location of each unit The resulting total capacitance of each parallel group, for each leg of the

unbalance measurement and for each phase. When measured at 1,1xUN in the mid-point between two unbalance legs, the highest measured unbalance in a healthy capacitor bank must not be more than 10% of the trip level of the unbalance protection. For small batteries (<20 MVA) unbalance of 20% of tripp level can be accepted.

5.6.3 Overload Capacity Unbalance capacity shall be as stated in the applicable standards.

5.6.4 Fuses When selecting concept for fuses, internal fuses are preferred. However external fuses can be accepted with the prerequisite that it is possible to coordinate protections and fuses. In case of external fuses, there shall be a mechanical device that clearly indicates that a fuse has tripped. Fuses shall be selected having regard to:

The requirement in 5.6.1 above regarding highest allowed over-voltage across a healthy parallel unit.

The fuse must not trip or get degraded through the inrush currents to which they will be subjected during the lifetime of the capacitor bank. It shall be assumed that up to 1000 switchings with at least 10 minutes intervals might occur each year.

The fuse of a healthy unit shall not trip during a discharge from 2,5xUN peak during external short-circuits or short-circuit in a parallel unit. The supplier shall through documentation show that it is possible to coordinate the fuses and the relay protections.


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The fuse shall be able to ensure a safe tripping a faulty unit within the r.m.s. levels of 0,9xUN to 2,0xUN across the unit.

The isolation of the fuse shall be able to withstand at least 1,1xUN after tripping.

Other requirements on fuses are given in the referred standards.

5.6.5 Fuse-less Design A fuse-less design with so called “all film capacitor” is accepted for larger capacitor banks and higher voltages.

5.6.6 Discharge resistors Each capacitor unit shall be provided with an internal discharge resistor, designed according to applicable standards.

5.6.7 Containers The capacitor unit containers shall be designed to withstand the mechanical forces, which will occur during its lifetime, due to expansions and contractions caused by changes in temperature and electrical loadings. Furthermore, the mechanical resistance must be coordinated with the pressure that will occur during a fault leading to a fuse tripping. The manufacturer shall show that the container will withstand the overpressure caused by the most unfavourable combination of fault current and fuse tripping time. In case of fuse-less design, a capacitor rupture curve shall be included in the tender. When the container is filled with insulating liquid, there must be no air bubbles left once the container is sealed. The container shall be manufactured in accordance with the specified requirements on corrosion protection.

5.7 Current Transformers Additional requirement: A current transformer intended for unbalance protection shall be provided with at least two relay cores. Current transformers shall be designed and tested in accordance with the Technical Guidelines TR-02 and TR-04.

5.8 Current Limiting Reactor

5.8.1 Design Current limiting reactors are required in order to limit the high inrush current occurring when switching two or more parallel capacitor banks. The reactors shall be sized to eliminate unwanted tripping of the earth-fault protections. The reactors shall also be dimensioned so that the harmonics created during switching in of the bank does not disturb other equipment inside or around the substation. Verification of this shall be done by site measurements during commissioning tests. Current limiting reactors shall be design to protect the capacitor bank circuit-breaker.


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5.9 Insulators Insulators can be made in porcelain or composite. Insulators shall be made and tested according to standards above and IEC/TS 60815. In polluted areas insulators shall have increased creepage distances. The normal and increased creepage distances follows the table below. Increased creepage distances shall in first hand be used in the west coast area (about 30 km from coast up to Götaälv-vally up to lake Vänern). In areas where risk for icing is present the vertical insulators shall have an mean field strength axial along the insulator of not more than 85 kV/m (fas/earth) According to IEC 60815-2 corrections shall be made in increased creepage for porcelain insulators with an diameter above 300 mm. For composite insulators no diameter correction are needed. The recommendations for creepage distances are based on the relation between creepage distance and pollution levels in the figure below in accordance with IEC 60815-2 and IEC 60815-3.

Creepage distance, (unified specific creepage distance,USCD) as fuction of polluted level (SPS class)

The requirement for creepage distances for Insulators in normal and polluted

environment. In the Swedish grids normally class b and d is used, and the creepage

distances can be seen in the table below:

Min krypsträcka, mm

Porcelain and Composite Rated voltage, Um

kV Smutsig miljö (klass d)1

Normal miljö (klass b)1

12 300 200 24 600 400 36 900 580 52 1300 840

82,5 2070 1325 145 3625 2330 170 4250 2730 245 6125 3940 420 10500 6750


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1) Enligt IEC 60815-1

5.10 Earthing Earthing shall be designed and installed in accordance with the requirements of VAST – Vattenfall: Jordningar av stationer och ställverk (earthing of substations and switchgear) 1987. Earth connections to supports shall be made by cable lugs with two holes. The earth wires shall be installed so that the risks of corrosion, abrasion damages and burns through contacts with other materials are eliminated.

5.11 Protective Fencing All live equipment, located less than 2500 mm above ground surface, shall be surrounded by a protective fence. See SS 421 01 01.

5.12 Thermovision Measurements All connectors and conductor joints on capacitor units and the completed bank, shall be subjected to thermovision measurements before the final acceptance.

6 Rating Plates and other Signs

6.1 General All rating pates shall be made of 1,2 mm engraved steel with lettering in baked enamel or a 25 μm thick layer of anodised aluminium. Any other design must be approved by the purchaser. Other signs and markings shall be supplied in accordance with TR1-16.

6.2 Capacitor Unit Rating Plate All capacitor units shall be provided with rating plates in accordance with the applicable standard. The measured capacitance values shall be stated on the rating plate.

6.3 Capacitor Rack Rating Plate Each rack shall be provided with a rating plate stating the physical location within the bank and the total weight of the rack with installed capacitors.

6.4 Capacitor Bank Rating Plate The complete capacitor bank shall be provided with a rating plate, installed at a suitable location, easily readable, in the centre of the connection bay. The rating plate shall include the following information:

Manufacturer


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Serial number Rated power in MVAr at rated voltage (=highest voltage for equipment if not

other agreed) Highest voltage for equipment of the capacitor bank Rated capacitance in μF for each leg of all three phases Rated insulation level Connection vector diagram Shortest allowed time between tripping and reclosing Year of manufacture and total weight

7 Lifting Devices

The supply shall include a simple device for lifting, removing and replacing faulty capacitor units in the bank.

8 Spare Parts for the Capacitor Bank

The following spare parts shall be included in the delivery of a capacitor bank: Capacitor units: 25% of the total number supplied Support insulators: 25%, at least one of each type supplied External fuses: 10% (if applicable)

9 Testing

9.1 Type Tests Type tests are required in accordance with the standards listed under Item 1 above. Endurance tests in accordance with the standard are required.

9.2 Routine Tests Routine tests shall be performed in accordance with the specified standards.


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10 Documentation

10.1 General Instructions, dimension drawings and schematics that are included in the delivery shall have all text written in the Swedish language.

10.2 Documentation Included in Tender With the tender the following documents shall be provided: List of data, dimension drawings, electrical circuit and schematic diagrams,

instructions for erection, operation and maintenance, type test certificates and also other documents needed for the technical evaluation.

Bases for evaluation of the need and costs for maintenance, such as: o The interval for condition control and other measures of maintenance and

the time necessary for these works. o Necessary spares, special tools and accessories and the costs for these.

Environmental information as below (see also TR 13-01E): o The interval for condition control and other measures of maintenance and

the time necessary for these works. o Information about the main content of the equipment (type of material in

percentage of weight) Information about the content of dangerous substances (for example heavy metals, carcinogenic compounds and compounds hard to biodegrade, xenobiotic substances)

o Handling and treating of the equipment when it has served its time.

10.3 Documentation Included in Delivery If not agreed otherwise, the following documentation shall be submitted in paper and electronic form, together with the delivery of the equipment: A list of documentation including:

Contract and order number Manufacture Type designations Serial numbers Rated data Type test reports

Information about the following documents shall be provided at the same time as the list above:

Assembly drawings with drawing lists Instructions for transport, storage, installation, maintenance, testing,

condition monitoring and adjustments. List of chemicals List of goods and safety information for all chemical products List of special tools and accessories for installation and maintenance List of equipment for testing and condition monitoring Spare parts list List of material for repair Final dimension drawings Final principle and connection diagrams


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Routine test reports Filled in data sheets

On behalf of the maintenance organisation of the purchaser a set of documentation, clearly defined for each supply, shall be submitted. The technical documentation shall allow the purchaser to establish a spare parts and maintenance organisation. It shall also be possible to use the documentation for training of supervisors, storage and service staff. The documentation shall specify prerequisites for condition monitoring and evaluation, as well as planning and performing of maintenance activities based on the risk assessment of the purchaser. The list of documentation shall cover assembly drawings valid for the equipment in question. Details of and applicable data for a specific device or a series of devices of the same type shall be identifiable through the documentation list. This means that the valid version of documents shall be clearly stated in the documentation list. It shall be possible to identify standardised mechanical components for purchase in Swedish specialist stores. See also SS-EN 60694. At the time of the first delivery, the documents presented in the list, shall be submitted in one printable version, collected in one set that can be used by the purchaser to create a service handbook. For additional supplies, only amended drawings, documents and instruction, together with advice for insertion, need to be supplied.

10.4 Documentation and Spare Parts After Delivery The supplier shall upon request provide the purchaser with required information and during at least ten years after delivery, be able to provide spare parts required for maintenance. Design changes or modified instructions, applicable for the supplied equipment, shall after delivery be submitted in the form of service bulletins. See also SS-EN 60694.


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11 Appendix

11.1 Appendix 1. Design and main data Conditions of operation:

Installation [Indoor / Outdoor] Temperature class [-25/A, -40/A or –

50/A] Environmental pollution level [Normal, salt or

industrial] Corrosion protection [Normal / Increased] Creepage distance [Normal / Increased]

Rated power at rated voltage: kVAr Allowed tolerance for capacitance value: % Connection type of bank:

Bridge connection with separate unbalance measurement for each phase or double Y

connection. If other connection or unbalance measurement is quoted the sensitivity of unbalance protection shall be presented.

Neutral connection [Isolated / Solid earth] Insulation level LIW kV SIWL kV (400 kV only) PF kV Insulation level neutral (if isolated) kV (LIWL) Short time overvoltage (15 min) kV


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11.2 Appendix 2 Data for capacitors

Deskription Value Unit Remarks

General

Site * Given by the contractor ie Hagby, CT65

Object id/Littera * Given by the contractor ie EK1

Manufacturer * Ie ABB

Ordernumber *

Manufacturing-number

*

Year of manufacturing

* year Ie 2007

Standard, Guideline * Ie IEC 60871-1 2005, TR1-17 E revC

Type of battery * Ie QBANK-A

Typ of Capacitor Unit * Ie CHDB182

Use * Outdoor or indor

Lowest temperature oC Ie -50

Rated Voltage (=highest voltage for equipment )

kV

Reactive Power at Rated voltage

MVA Ie 300MVA

Total mass ton

Volume of insulating fluid

kg

Type of insulating fluid

* Ie Faradol

Spraying permitted * Yes/No/otional


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Rated Voltage Unit* kV

Capacitans (for serie capacitors)

mF Ie 50mF

Current (for serie capacitors)

A

Number of unit connected in serie

* no Ie 80

Connection * Ie dubbleY (YOH)

Date of reconstruction

year Ie 1988

Overvieu * Document No

Outline * Document No

Maintenance * Document No

Circuits * Document No

Creepage distance mm Ie 80mm

Data of Unit * Document No

Documents

Shunt Capacitors