BUREAU OF INDIAN STANDARDS

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1 BUREAU OF INDIAN STANDARDS Manak Bhavan, 9 Bahadur Shah Zafar Marg New Delhi Phones TeleFax Website : Extn eetd@bis.org.in य प च ल म म द तपम प दम तत : ईट र षत : 1. ईट 15 क सभ सद य 2. व य त तकन क व भ ग पर षद क सभ सद य त 3. च खन ल अ य सभ नक य र ख रषण द ञ म द भ द म प ईट 15/ट 101, ट मह दय, क य न नलल खखत मस द क एकएक र त स ल न ह : र ख द य श षभप 1. रल ख : ईट घ ण व य त मश न 3 फ ज़ ल घ ण व य तमश न क टलम नल ब स क व लश टट 2. रल ख : ईट घ ण व य त मश न भ ग 31 पर त न य ग त अन रय ग सहहत ऊ दष म ट क यन अन रय ग ग ईड क य न मस द क अ ल कन क अपन स म तय यह बत त ह ए भ क अ तत: यहद य म नक क प म रक लशत ह ऍ त न प अमल क न म आपक य स य अ क ब म य कह न य आ सकत ह स म तय यहद क ई ह त क य अगल प ट प हदए प म अ ह त ष क रपर ललखखत पत प भ द यहद क ई स म त र त नह ह त अ स म त म क ल भ ष स ब हट ह ई त रप त रल ख क य त अ त म प हदय एग यहद क ई स म त तकन क रक त क ह ई त व षय सलम त क अ यष क प मश स अ रनक छ प आग क क य ह क ललए व षय सलम त क भ न क ब द रल ख क अ त म प द हदय एग स म तय भ न क अ तम त ख य द, भ द य, ड ग व व ञ तमप एफ एव र ख (वव य त तपम प ) स ल न : रप ललखखत

2 BUREAU OF INDIAN STANDARDS Manak Bhavan, 9 Bahadur Shah Zafar Marg New Delhi Phones TeleFax Website : Extn eetd@bis.org.in DRAFTS IN WIDE CIRCULATION Document Despatch Advice REFERENCE DATE TECHNICAL COMMITTEE ETD 15 ADDRESSED TO: 1 All Members of Rotating Machinery Sectional Committee, ET 15; 2. All Members of Electrotechnical Division Council; and 3. All other Interested. Dear Sir(s), Please find enclosed a copy of the following draft Indian Standard: ETD 15/ T 101, T DOC NO. ET 15 (6897) ET 15 (6898) TITLE Rotating Electrical Machines Specification for Terminal Boxes for 3 Phase Rotating Electrical Machines Rotating Electrical Machines Part 31 : Selection of energyefficient motors including variable speed applications Application guide (IEC :2010) Kindly examine the draft standard and forward your views stating any difficulties which you are likely to experience in your business or profession, if these are finally adopted as Indian Standards. In case, you need a copy of the document, kindly send us your mailing address. Comments, if any, may please be made in the format given overleaf and mailed to the undersigned. Last date for comments: In case no comments are received or comments received are of editorial nature, you will kindly permit us to presume your approval for the above document as finalized. However, in case of comments of technical in nature are received then it may be finalized either in consultation with the Chairman, Sectional Committee or referred to the Sectional Committee for further necessary action, if so desired by the Chairman, Sectional Committee. Thanking you, Yours faithfully (D Goswami) Sc F & Head (Electrotechnical) eetd@bis.org.in Encl: As above

3 Date Document No ET 15 (6897), ET 15 (6898) Sl. No. Name of the Organization Clause/ Subclause Paragraph/ Figure/Table Type of Comment (General/ Technical/ Editorial Comments Proposed Change

4 Doc: ET 15(6897) BUREAU OF INDIAN STANDARDS DRAFT FOR COMMENTS ONLY (Not to be reproduced without the permission of BIS or used as Indian Standard) Draft Indian Standard ROTATING ELECTRICAL MACHINES: SPECIFICATION FOR TERMINAL BOXES FOR 3 PHASE ROTATING ELECTRICAL MACHINES Last date for receipt of comments is Foreword (Formal clauses will be added later) 1 SCOPE This standard specifies types and performance requirements for terminal box for 3 phase rotating electrical machines for rated voltages up to 15 kv rms. This standard also specifies requirements of the terminations of the machines to withstand high energy fault. However, it is to be noted that, withstand high energy fault is not a standard feature of the terminal box of machines with rated voltage up to and including 690 volts. In such case, the design of terminal box will be entirely different and may be inappropriate to the size of the machine itself. For machines with rated voltages up to and including 690 volts, it is assumed that, fuses or other energy limiting devices would protect the machine. The standard applies to terminal boxes and terminal enclosures, but it does not specify the requirements for flameproof terminal enclosures. The choice of a particular termination will be largely governed by the service and environmental conditions, but the standard is also relevant to the various types of cables normally used, including aluminium and, where applicable, cable spreader boxes. The scope of this standard does not cover the external supply cables in detail, but insofar as the design of the terminals is concerned, essential data is listed. Terminal boxes for small rating machines having rated outputs up to and including 0.75 kw or kva per 1000 r/min are not covered by this standard.

5 2 REFERENCES The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.. BS:4999:part145:1997 Specification of winding terminations BS 5372:1997 Dimensions of cable terminations for multi core extruded solid dielectric insulated distribution cables of rated voltages 600/1000 and 1900/3300V having copper or aluminium conductor.. CEGB standard Issue 2 Sept ESI Standard 443 ; Issue 1 January TERMS AND DEFINITIONS For the purposes of this document, the definitions in IEC and the following definitions apply. For the purposes of this standard, the term agreement means agreement between the manufacturer and purchaser. 3.1 Type Test A test of one or more machines made to a certain design to show that the design meets certain specifications. [IEV ] NOTE The type test may also be considered valid if it is made on a machine, which has minor deviations of rating or other characteristics. These deviations should be subject to agreement. 3.2 Routine Test A test to which each individual machine is subjected during or after manufacture to ascertain whether it complies with certain criteria. [IEV ] 3.3 Degree of Protection As defined in IEC : 2000, Short Circuit The accidental or intentional connection, by a relatively low resistance or impedance, of two or more points in a circuit which are normally at different voltages. 1

6 3.5 Short Circuit Current An over current resulting from a short circuit due to a fault or an incorrect connection in an electric circuit (IEV ). NOTE The Short Circuit current levels defined in this standard is due to short circuits at the line terminals inside the terminal box. 3.6 Gland Plate The plate provided at the bottom of terminal box facilitating cable entry to the motor from either top, bottom or side. 3.7 Low Voltage From 200V up to 1000V 3.8 High Voltage Above 1000V up to V 3.9 Termination The arrangement provided for making the connections between the machine winding leads and the external conductors Terminal A conducting element of a winding intended for connection to an external electrical conductor Stud Terminals A form of termination in which the terminals are stud mounted integral with the machine frame or in a separate terminal enclosure Strip terminals A form of termination in which the terminals are strip mounted integral with the machine frame or assembly Flexible Leads A form of termination in which the ends of the machine winding are brought out as unsupported insulated flexible conductors. 2

7 3.14 Air Insulated Termination A termination so designed that the protection of phase conductors against electrical failure is by adequately spaced bare conductors with appropriate insulated supports Cable Coupler A form of termination in which the terminals are connected to the supply leads by means of a plug and socket device Separable Insulated Connectors A form of termination comprising a molded bushing and insulated elbow connector coupling Separate Terminal Enclosure A form of termination in which the terminals are connected to the incoming supply leads inside a chamber, which need not be fully enclosed and may be formed by the foundations beneath the machine Terminal Box A type of terminal enclosure in which the terminals are connected to the incoming supply leads inside a box. which encloses the connections and is of a size consistent to suit the Rated r.m.s. current with adequate access and with adequate clearances and creepage distances suitable for the highest system Voltage requirements Pressure Relief Terminal Box A terminal box such that internal fault energy is relieved through a pressure relief diaphragm without any disintegration of the front side exposed to operating Personnel Pressure Containing terminal Box A terminal box such that the Internal fault energy is withstood without any disintegration from Outside surface Flameproof Terminal Box A terminal box designed to comply with additional flameproof requirements of IEC Increased Safety Terminal Box A terminal box designed to comply with additional Increased Safety requirements of IEC Air Insulated Terminal Box A terminal box so designed that the protection of phase conductors against electrical fault within the terminal box is ensured by adequate air gap, with or without appropriate insulated supports. 3

8 3.24 Phase Insulated Terminal Box A terminal box so designed that the protection of phase conductors against electrical failure within the terminal box is separated mainly by solid insulation Phase Separated Terminal Box A terminal box so designed that phase separation is provided by earthed metal barriers so as to restrict any electrical breakdown between phases Phase Segregated Terminal Box A terminal box so designed that phase segregation is provided by Insulated barriers so as to restrict any electrical break down between phases and / or phase to earth 4 SERVICE CONDITIONS The Terminal Box shall be designed to suit operating site conditions specified for rotating electrical machine, unless otherwise specified by the purchaser: 5 MATERIAL FOR CONSTRUCTION 5.1 Low Voltage Machines Terminal box shall generally be of metal and adequately sized to terminate either copper or aluminum conductor cables. The motor manufacturer shall ensure the type of cable envisaged (copper or aluminium) prior to manufacturing of the terminal box. In other than hazardous locations, non metallic, non burning materials for terminal boxes may be used provided internal grounding means between the machine frame and the equipment grounding connection is incorporated into the terminal box. However, these terminal boxes shall meet the requirements of short circuit test as per table5. In case cable end boxes are provided, the same may be of steel or cast iron; for single core cables the cable end plate shall be of non magnetic material. 5.2 High Voltage Machines Terminal box shall be of metal and adequately sized to terminate either copper or aluminum conductor cables. The motor manufacturer shall ensure the type of cable envisaged (copper or aluminium) prior to manufacturing of the terminal box. In case cable end boxes are provided, the same may be of steel or cast iron; for single core cables the cable end plate shall be of non magnetic material. 6 ARRANGEMENTS AND ENCLOSURES 4

9 Terminal box shall have a degree of Protection as per clause 13 such that it remains clean and dry internally in service. The arrangements shall embody the relevant features selected from table 1. The Pressure relief device/ diaphragm should be so located that any relief from it should not get dissipated away from the Motor or relief should be toward the motor on which it is mounted. Table 1 (Clauses 6 and 11) Combinations for termination assembly Sl No. (1) i) ii) iii) iv) v) Terminal Arrangement (2) Air insulated Phase insulated Phase separated Phase segregated Separate terminal Enclosure Terminal Type (3) Stud Bushing Strip Cable coupler Flexible leads Type of Energy Dissipation in Case of the Terminal Box for High Fault Levels V>=1100, MVA>=value in table 5 (4) Pressure containing Terminal box or Pressure relief Terminal box NOTE The combination is to consist of any one of the termination arrangements given in column 1 combined with any one of the conducting parts given in column 2, combined with, for high fault levels, either of the terminal boxes given in column 3. 7 DIMENSIONS OF CABLE TERMINATION Fig 1 5

10 7.1 Cable Sizes The terminal box shall be suitable to accommodate the size and number of cables as agreed between manufacturer and purchaser. LV motor terminal box shall have gland plates suitable to terminate cables according to table2. This table is only for guidance purpose. Table 2 (Clauses7.1 and 8) Dimensions of Cable Terminations for 3 and 4 Core Extruded Solid Dielectric Insulated Distribution Cables of Rated Voltages 600/1100 volts and 3 core Cables of Rated Voltages, 1900/3300 volts having Copper or Aluminium Conductors Sl No. Dimensions and Current rating of Cable Terminations for 600/1000 V Cross Section Aluminum Cable Copper Cable Minimum Area of Cable B (Minimum) F H Current Rating B (In (Minimum) F H Current Rating Earthing (In Terminal Conductor ground) ground) size inside mm² with Deration with Deration terminal box Factor of Factor of (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) i) / / M5 ii) / / M5 iii) / / M5 iv) / / M5 v) / / M5 vi) / / M8 vii) / / M8 viii) / / M8 ix) / / M8 x) / / M10 xi) / / M10 xii) / / M10 xiii) / / M12 xiv) 2x / / M10 xv) 3x / / M10 xvi) 4x / / M10 xvii) 2x / / M10 xviii) 3x / / M10 xix) 4x / / M10 xx) 2x / / M10 6

11 xxi) 3x / / M10 xxii) 4x / / M10 xxiii) 2x / / M12 xxiv) 3x / / M12 xxv) 4x / / M12 NOTES 1 The current rating of the cable is based upon a deration factor of For HT motors the distance between gland plate and the terminal studs shall not be less than 500 mm. 7.2 Factors, which Affects Cable Accommodation The limitations imposed by a number of factors as detailed in a, b, c have been taken into account in determining the length required in the terminal enclosure to accommodate the cable cores (dimension B in Fig.1). a) Terminal lugs: Terminal lugs of compression type are usually longer than those of other types. b) Layout of cable cores: The dimensions specified in above table allow for the cores to be crossed within the enclosure. However, if the terminal enclosure allows for the entry of two or more cables, it will be necessary to increase dimension B to allow for crossing a greater number of cable cores. c) Type of terminal box; Phase segregation or phase separated. 8 EARTHING IN TERMINAL BOX When motors are provided with terminal box for fixed terminal connections, a means for earthing of terminal box shall be provided inside or outside the terminal box. A screw stud or bolt intended for the termination of earthing conductor shall not be smaller than mentioned in Table 2. When a terminal box mounting screw stud or bolt is used to secure the earthing conductor to the main terminal box, there shall be at least one other equivalent securing means for fixing the terminal box to the machine frame. NOTE Use of.3½ core cables is recommended for effective earthing of terminal box. 9 ELECTRICAL CLEARANCES With the components of the terminations in the correct position, the clearances.and creepage distances shall be not less than the values given in Table 3 and 4 as applicable. Further, the clearances provided shall be adequate between cable lugs (that is equal to or higher than the value indicated in table below) at termination to ensure ease of Copper or Aluminium cable installation. Table 3 (Clause 9) Minimum Clearance Distances (mm) in Air between Phase to Earth or between Phases Sl No. (1) Nominal Voltage (2) Machines with Frame Sizes Up to ,200 and 225 Rating of Machine at Nominal Voltage Up to 22 kw (3) Above 22 kw Up to 75 kw (4) 250 and Above 75kW Up to 185 kw (5) Above 185 kw (6) 7

12 i) ii) iii) iv) v) vi) vii) viii) ix) Upto Table 4 (Clause 9) Minimum Creepage Distances (mm) between Phase to Earth or between Phases Sl No. Nominal Voltage Machines with Frame Sizes Up to ,200 and and Rating of other Machine at Nominal Voltage (1) i) ii) iii) iv) v) vi) vii) viii) ix) (2) Upto Up to 22 kw (3) 11.2 Above 22 kw Up to 75 kw (4) 12.5 Above 75kW Up to 185 kw (5) Above 185 kw (6) NOTES: 1. Some designs of pressure containing type terminal boxes may require the use of clearance and creepage distances smaller than the values given in tables 3,. and The values given are for air insulated terminal boxes. These can be considerably less for phase separated and phase insulated terminal boxes. 3. For Phase segregated terminal boxes the clearance and creepage values are left to the manufacturer s design, except that these will have to pass the tests given in sec. 15 (b) 10 POSITION OF TERMINAL BOX For footmounted machines of frame size 56 to 315, the following shall apply: 10.1 The terminal box shall be so located on the righthand side, when looking at the driving end of the motor, that there is adequate clearance between cable end plate and ground for ease of routing and termination of cables; 10.2 It is recommended that unless the terminal box is on the top, the motors shall be so 8

13 constructed that the terminal box may be located on the lefthand side by the manufacturer, if requested by the user at the time the motor is ordered. NOTES 1. Provision should preferably be made so as to enable cable entry to the terminal box in any one of four directions at right angles. 2. The terminal box should be separated from main stator frame through a suitable barrier plate / or similar arrangement, so as to prevent any foreign particles/objects falling inside the stator. 11 ABILITY OF TERMINATIONS FOR MACHINES RATED AT 1100V AND ABOVE TO WITHSTAND SYSTEM FAULTS Machine primary winding terminations, including internal flexible cables and connection cables between the power supply cables and the motor windings, of machines for use on electrical systems having nominal short circuit MVA capacities equal to or greater than those in Table 1 shall be so rated that they will safely carry the fault current for the specified duration. Sl No. NOTE The fault clearance time is usually assumed to be not longer than 0.25 s for machines protected by circuit breakers. Table 5 (Clauses 5.1 and 11) Nominal Shortcircuit Capacity Operating Voltage Fault Level (MVA) Time Duration for Withstanding (4) (1) (2) (3) i) 11kV SEC ii) 6.6kV to 11 KV SEC iii) >3.3kV to 6.6 KV SEC iv) 690V to 3.3 KV SEC v) Up to 690V SEC Terminal boxes for machines protected by circuit breakers and having nominal short circuit capacities equal to or higher than those in table 5 shall be of either the pressure relief or pressure containing type. NOTE All motors upto and including 75kW/90kW shall be deemed to have fuse protection. Where motors are with only MCB and there is no fuse wire in circuit, then the terminal box shall be made suitable for with standing a short circuit capacity of 35MVA for 0.25 secs 12 DEGREE OF PROTECTION The degree of protection for terminal boxes shall minimum be that for its motor. However degree of protection of IP54 and above may be considered for user specific requirements. 13 TERMINATION FOR MOTOR AUXILIARIES 9

14 The termination for motor auxiliaries shall be provided in a separate auxiliary terminal box or inside the main terminal box as agreed between the manufacturer and the purchaser. Separate auxiliary terminal box whenever provided shall meet constructional requirements of terminal box indicated at 6 & 7. The short circuit test is not required to be conducted on auxiliary terminal box. 14 TESTS The following type tests shall be conducted for motor Terminal Box (a) Degree of protection test for the terminal box (This test may also be conducted with the TB mounted on the motor at the time of DOP Test for motor). (b) Terminal boxfault level withstand test. The short circuit withstand ability test may be classified as: (i) Three phase through fault current test. (ii) Internal arc fault current test: Three phase to ground internal arc fault current test for air and phase insulated boxes Single phase to ground internal arc fault current test. insulated 15 TEST PROCEDURE FOR SHORT CIRCUIT TEST ON MOTOR TERMINAL BOX The short circuit withstand ability tests classified above may be conducted as per the requirements of the manufacturers/purchasers. However, for guidance purpose, the test procedure is laid below. The terminal box used for the above tests shall be new and in good condition. The terminal box shall be fitted with incoming and outgoing bolted terminals and with a suitable cross section of cable of length 3 to 5 meters to be connected between the testing source and incoming terminals of terminal box. The terminal box shall be mounted on an iron frame in order to mount the structure firmly on the test cell. The outgoing bolted terminals of the terminal box shall be shorted with suitable cross section of copper links or with flexible ropes Test quantities The test quantities such as short circuit current, voltage and duration of the fault current shall be defined by the manufacturer/utility before the commencement of the test. The 10

15 tolerance on the current and voltage also be defined be the manufacturer/utility Details of Short Circuit Withstand ability Tests to be Performed Through Fault Current Test ( 3Phase through Fault Test) For through fault current test, the terminal box is connected as per Test Circuit Diagram given below and all the three phase outgoing terminals shorted outside the terminal box with suitable cross section of copper links or with flexible copper ropes. The specified short circuit current for the specified test duration shall be applied by the test source. On completion of the test, the condition of the terminal box shall be inspected. The terminal box is deemed to have passed the test if no external damage to the terminal box, including pressure relief device, is noticed (other than operation of pressure relief device). 1 Short circuit generator 2 Master breaker 3 Reactors variable in steps 4 Make switch 5 LV transformer with neutral earthed via shunt 6 Equipment under test Internal Arc Fault Current Test Three phase to ground internal arc fault current test For three phase to ground internal arc fault current test, the terminal box is connected as per Test Circuit Diagram given below. The three phase to ground short circuit is created by a tinned copper wire of 0.5mm diameter cross section inside the terminal box. The short circuit current at specified test voltage for the specified test duration shall be applied by the test source. On completion of the test, the condition of the terminal box shall be inspected. The terminal box is deemed to have passed the tests if no external damage to the terminal box 11

16 from terminal box cover side is noticed. Pressure relief device, if any incorporated in the terminal box, should operate safely. The damaged component if any, should either get vented through pressure relief device or remain inside the box. For pressure containing type, the box should neither disintegrate nor any damaged component come out of the Terminal Box. 1 Short circuit generator 2 Master breaker 3 Reactors variable in steps 4 Make switch 5 Terminal box under test 6 Fuse element 7 Series resistors for voltage measurement 8 Current transformer for current measurement Test conditions: Short circuit point: grounded Source neutral: isolated Single phase to ground internal arc fault current test For single phase to ground internal arc fault current test, the terminal box is connected as per Test Circuit Diagram given below. The single phase to ground short circuit is created by a tinned copper wire of 0.5mm dia cross section inside the terminal box. The short circuit current at specified test voltage for the specified test duration shall be applied by the test source. On completion of the test, the condition of the terminal box shall be inspected. The terminal box is deemed to have passed the tests if no external damage to the terminal box from terminal box cover side is noticed. Pressure relief device, if any incorporated in the terminal box, should operate safely. The damaged component if any, should either get vented through pressure relief device or remain inside the box. NOTES 1. For pressure containing type, the box should neither disintegrate from outside surface nor damaged component should come out of the Terminal Box. 2. For phase separated and phase segregated box, the test shall not result in to flow of current in other two phases, which 12

17 are at rated voltage during the duration of the test. 1 Short circuit generator 2 Master breaker 3 Reactors variable in steps 4 Make switch 5 Terminal box under test 6 Fuse element 7 Series resistors for voltage measurement Test conditions: Short circuit point: grounded Source neutral: isolated 16 TEST REPORTS The test report for the above tests shall have all the relevant drawings of the terminal box with complete details like: a) Material of construction b) Technical data sheet of terminal box c) Oscilloscope waveform and d) Peak to peak current observed and its duration. 13

18 Doc: ETD 15(6898) BUREAU OF INDIAN STANDARDS DRAFT FOR COMMENTS ONLY (Not to be reproduced without the permission of BIS or used as Indian Standard) Draft Indian Standard ROTATING ELECTRICAL MACHINES PART 31: SELECTION OF ENERGYEFFICIENT MOTORS INCLUDING VARIABLE SPEED APPLICATIONS APPLICATION GUIDE Last date for receipt of comments is Rotating Machinery Sectional Committee, ETD 15 NATIONAL FOREWORD This Indian Standard (Part 31) which is identical with IEC : 2007 Rotating electrical machines Part 31: Selection of energyefficient motors including variable speed applications Application guide issued by the International Electrotechnical Commission (IEC) was adopted by the Bureau of Indian Standards on the recommendation of the Rotating Machinery Sectional Committee and approval of the Electrotechnical Division Council. The text of IEC Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminology and conventions are however not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words International Standard appear referring to this standard, they should be read as Indian Standard. b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker. In this adopted standard, references appear to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards, which are to be substituted in their places, are listed below along with their degree of equivalence for the editions indicated: International Standard Corresponding Indian Standard Degree of Equivalence IEC Rotating electrical machines IS/IEC :2004 Rotating Identical with Part 1: Rating and performance electrical machines Part 1: Rating and performance IEC : 2004

19 The technical committee has reviewed the provisions of the following International Standards referred in this adopted standard and has decided that they are acceptable for use in conjunction with this standard: International Standard IEC Title Rotating electrical machines Part 30: Efficiency classes of singlespeed threephase, cage induction motors (IEcode Only the English language text of the IEC Standard has been retained while adopting it in this Indian Standard and as such the page numbers given here are not the same as in the IEC standard. For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated expressing the result of a test, shall be rounded off in accordance with IS 2 : 1960 Rules for rounding of numerical values (revised). The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. ii