This part of IEC 60947 is applicable to the following equipment:<\/p>\n
electromechanical contactors and starters including motor protective switching device (MPSD);<\/p>\n<\/li>\n
actuators of contactor relays;<\/p>\n<\/li>\n
contacts dedicated exclusively to the coil circuit of this contactor or this contactor relay;<\/p>\n<\/li>\n
dedicated accessories (e.g. dedicated wiring, dedicated latch accessory);<\/p>\n<\/li>\n<\/ul>\n
intended to be connected to distribution circuits, motors circuits and other load circuits, the rated voltage of which does not exceed 1 000 V AC or 1 500 V DC.<\/p>\n
This document covers also the assessment procedure for electromechanical overload protection used in safety applications such as protecting a motor located in explosive atmosphere from the outside atmosphere: See Annex L.<\/p>\n
This document does not apply to:<\/p>\n
starters for DC motors 1<\/sup>;<\/p>\n NOTE 1 The requirements for DC motor starters are under consideration for the next maintenance cycle.<\/p>\n<\/blockquote>\n<\/li>\n auxiliary contacts of contactors and contacts of contactor relays. These are covered by IEC 60947-5-1;<\/p>\n<\/li>\n starter used downstream to frequency drive1;<\/p>\n NOTE 2 Additional requirements for starter used downstream to frequency drive are under consideration for the next maintenance cycle.<\/p>\n<\/blockquote>\n<\/li>\n short-circuit protective device integrated within starters other than MPSDs. This is covered by IEC 60947-2 and IEC 60947-3;<\/p>\n<\/li>\n the use of the product with additional measure within explosive atmospheres. These are given in IEC 60079 series;<\/p>\n<\/li>\n embedded software design rules1<\/sup>;<\/p>\n<\/li>\n cyber security aspects. These are covered by IEC 62443 series.<\/p>\n<\/li>\n<\/ul>\n The objective of this document is to state:<\/p>\n the characteristics of the equipment;<\/p>\n<\/li>\n the conditions applicable to the equipment with reference to:<\/p>\n its operation and behaviour,<\/p>\n<\/li>\n its dielectric properties,<\/p>\n<\/li>\n its degree of protection,<\/p>\n<\/li>\n its construction including safety measures against electric shock, fire hazard and mechanical hazard;<\/p>\n<\/li>\n<\/ol>\n<\/li>\n the tests intended for confirming that these conditions have been met, and the methods to be adopted for these tests;<\/p>\n<\/li>\n the information to be given with the equipment or in the manufacturer’s literature.<\/p>\n<\/li>\n<\/ol>\n Low-voltage switchgear and controlgear – Contactors and motor-starters. Electromechanical contactors and motor-starters<\/b><\/p>\n\n
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PDF Catalog<\/h4>\n
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\n PDF Pages<\/th>\n PDF Title<\/th>\n<\/tr>\n \n 2<\/td>\n undefined <\/td>\n<\/tr>\n \n 8<\/td>\n Annex ZA(normative)Normative references to international publicationswith their corresponding European publications <\/td>\n<\/tr>\n \n 15<\/td>\n English
CONTENTS <\/td>\n<\/tr>\n\n 23<\/td>\n FOREWORD <\/td>\n<\/tr>\n \n 26<\/td>\n INTRODUCTION <\/td>\n<\/tr>\n \n 27<\/td>\n 1 Scope <\/td>\n<\/tr>\n \n 28<\/td>\n 2 Normative references <\/td>\n<\/tr>\n \n 29<\/td>\n 3 Terms, definitions, symbols and abbreviated terms
3.1 General
3.2 Alphabetical index of terms <\/td>\n<\/tr>\n\n 31<\/td>\n 3.3 Terms and definitions concerning contactors <\/td>\n<\/tr>\n \n 32<\/td>\n 3.4 Terms and definitions concerning starters <\/td>\n<\/tr>\n \n 38<\/td>\n 3.5 Terms and definitions concerning characteristic quantities <\/td>\n<\/tr>\n \n 39<\/td>\n 3.6 Terms and definitions concerning safety aspects <\/td>\n<\/tr>\n \n 40<\/td>\n 3.7 Symbols and abbreviated terms <\/td>\n<\/tr>\n \n 41<\/td>\n 4 Classification
5 Characteristics of contactors and starters
5.1 Summary of characteristics <\/td>\n<\/tr>\n\n 42<\/td>\n 5.2 Type of equipment
5.2.1 Kind of equipment
5.2.2 Number of poles
5.2.3 Kind of current (AC or DC)
5.2.4 Interrupting medium (air, oil, gas, vacuum, etc.)
5.2.5 Operating conditions of the equipment
5.3 Rated and limiting values for main circuits
5.3.1 Rated voltages <\/td>\n<\/tr>\n\n 44<\/td>\n 5.3.2 Currents or powers <\/td>\n<\/tr>\n \n 45<\/td>\n 5.3.3 Rated frequency
5.3.4 Rated duties <\/td>\n<\/tr>\n\n 46<\/td>\n 5.3.5 Normal load and overload characteristics <\/td>\n<\/tr>\n \n 48<\/td>\n 5.3.6 Short-circuit characteristics <\/td>\n<\/tr>\n \n 49<\/td>\n 5.3.7 Pole impedance of a contactor (Z)
5.4 Utilization category
5.4.1 General
5.4.2 Assignment of utilization categories based on the results of tests <\/td>\n<\/tr>\n\n 51<\/td>\n 5.5 Control circuits
Tables
Table 1 \u2013 Utilization categories <\/td>\n<\/tr>\n\n 52<\/td>\n 5.6 Auxiliary circuits
5.7 Characteristics of relay and release of overload relays and motor protective switching device (MPSD)
5.7.1 Summary of characteristics
5.7.2 Types of relay or release
5.7.3 Characteristic values <\/td>\n<\/tr>\n\n 54<\/td>\n 5.7.4 Designation and current settings of overload relays
5.7.5 Time-current characteristics of overload relays
Table 2 \u2013 Trip classes of overload relays <\/td>\n<\/tr>\n\n 55<\/td>\n 5.7.6 Influence of ambient air temperature
5.8 Co-ordination with short-circuit protective devices
5.9 Void
5.10 Types and characteristics of automatic change-over devices and automatic acceleration control devices
5.10.1 Types
5.10.2 Characteristics <\/td>\n<\/tr>\n\n 56<\/td>\n 5.11 Types and characteristics of auto-transformers for two-stepauto-transformer starters
5.12 Types and characteristics of starting resistors for rheostatic rotor starters
6 Product information
6.1 Nature of information
6.1.1 Identification <\/td>\n<\/tr>\n\n 57<\/td>\n 6.1.2 Characteristics, basic rated values and utilization <\/td>\n<\/tr>\n \n 58<\/td>\n 6.2 Marking <\/td>\n<\/tr>\n \n 59<\/td>\n 6.3 Instructions for installation, operation, maintenance, decommissioning and dismantling
6.4 Environmental information
7 Normal service, mounting and transport conditions <\/td>\n<\/tr>\n\n 60<\/td>\n 8 Constructional and performance requirements
8.1 Constructional requirements
8.1.1 General
8.1.2 Materials <\/td>\n<\/tr>\n\n 61<\/td>\n 8.1.3 Current-carrying parts and their connections
8.1.4 Clearances and creepage distances
8.1.5 Actuator <\/td>\n<\/tr>\n\n 62<\/td>\n 8.1.6 Indication of the contact position
8.1.7 Additional requirements for equipment suitable for isolation
8.1.8 Terminals
8.1.9 Additional requirements for equipment provided with a neutral pole
8.1.10 Provisions for protective earthing
8.1.11 Enclosures for equipment <\/td>\n<\/tr>\n\n 63<\/td>\n 8.1.12 Degrees of protection of enclosed equipment
8.1.13 Conduit pull-out, torque and bending with metallic conduits
8.1.14 Limited energy source <\/td>\n<\/tr>\n\n 64<\/td>\n Table 19 \u2013 Limits for limited energy sources without an over-current protective device
Table 20 \u2013 Limits for limited energy sources with an over-current protective device <\/td>\n<\/tr>\n\n 65<\/td>\n 8.1.15 Stored charge energy circuit
8.1.16 Fault and abnormal conditions
Table 21 \u2013 Limits for limited energy source with current limiting impedance <\/td>\n<\/tr>\n\n 66<\/td>\n 8.1.17 Short-circuit and overload protection of ports
8.2 Performance requirements
8.2.1 Operating conditions <\/td>\n<\/tr>\n\n 68<\/td>\n Table 3 \u2013 Limits of operation of time-delay overload relays when energized on all poles <\/td>\n<\/tr>\n \n 69<\/td>\n Figures
Figure 1 \u2013 Multiple of current setting limits for ambient air temperature compensated time-delay overload relays <\/td>\n<\/tr>\n\n 70<\/td>\n Figure 2 \u2013 Thermal memory test <\/td>\n<\/tr>\n \n 71<\/td>\n Table 4 \u2013 Limits of operation of three-pole time-delay overload relays when energized on two poles only <\/td>\n<\/tr>\n \n 72<\/td>\n 8.2.2 Temperature-rise <\/td>\n<\/tr>\n \n 73<\/td>\n Table 5 \u2013 Temperature-rise limits for insulated coils in air and in oil <\/td>\n<\/tr>\n \n 74<\/td>\n 8.2.3 Dielectric properties
Table 6 \u2013 Intermittent duty test cycle data <\/td>\n<\/tr>\n\n 75<\/td>\n 8.2.4 Normal load and overload performance requirements <\/td>\n<\/tr>\n \n 76<\/td>\n Table 7 \u2013 Making and breaking capacities \u2013 Making and breaking conditions according to utilization category <\/td>\n<\/tr>\n \n 78<\/td>\n Table 8 \u2013 Relationship between the test current and off-time forthe verification of rated making and breaking capacities
Table 9 \u2013 Operational current determination for utilization categories AC-6a and AC-6b when derived from AC-3 ratings <\/td>\n<\/tr>\n\n 79<\/td>\n Table 10 \u2013 Conventional operational performance \u2013 Making and breaking conditions according to utilization category <\/td>\n<\/tr>\n \n 81<\/td>\n 8.2.5 Co-ordination with short-circuit protective devices
Table 11 \u2013 Overload current withstand requirements <\/td>\n<\/tr>\n\n 83<\/td>\n Figure 3 \u2013 Examples of co-ordination characteristics of a starter
Table 15 \u2013 Test conditions for Icd <\/td>\n<\/tr>\n\n 84<\/td>\n 8.3 Electromagnetic compatibility (EMC)
8.3.1 General
8.3.2 Immunity <\/td>\n<\/tr>\n\n 85<\/td>\n 8.3.3 Emission
9 Tests
9.1 Kinds of test
9.1.1 General
Table 12 \u2013 Specific acceptance criteria for immunity tests <\/td>\n<\/tr>\n\n 86<\/td>\n 9.1.2 Type tests
9.1.3 Routine tests
9.1.4 Sampling tests <\/td>\n<\/tr>\n\n 87<\/td>\n 9.1.5 Special tests <\/td>\n<\/tr>\n \n 88<\/td>\n 9.2 Compliance with constructional requirements
9.2.1 General
9.2.2 Electrical performance of screwless-type clamping units
9.2.3 Ageing test for screwless-type clamping units
Figure 4 \u2013 Voltage drop measurement at contact point of the clamping terminal <\/td>\n<\/tr>\n\n 89<\/td>\n 9.2.4 Limited energy source test
9.2.5 Breakdown of components <\/td>\n<\/tr>\n\n 90<\/td>\n 9.3 Compliance with performance requirements
9.3.1 Test sequences <\/td>\n<\/tr>\n\n 91<\/td>\n 9.3.2 General test conditions
9.3.3 Performance under no load, normal load and overload conditions <\/td>\n<\/tr>\n\n 94<\/td>\n Figure 5 \u2013 Example of a pole impedance measurement for a 3 pole contactor <\/td>\n<\/tr>\n \n 103<\/td>\n 9.3.4 Performance under short-circuit conditions <\/td>\n<\/tr>\n \n 105<\/td>\n Table 13 \u2013 Value of the prospective test current according to the rated operational current
Table 14 \u2013 Value of the prospective test current according to the rated operational current (harmonized table) <\/td>\n<\/tr>\n\n 108<\/td>\n 9.3.5 Overload current withstand capability of contactors
9.3.6 Routine tests and sampling tests <\/td>\n<\/tr>\n\n 110<\/td>\n 9.4 EMC tests
9.4.1 General
9.4.2 Immunity
Table 16 \u2013 EMC immunity tests <\/td>\n<\/tr>\n\n 112<\/td>\n 9.4.3 Emission
Table 17 \u2013 Terminal disturbance voltage limits for conducted radio-frequency emission (for mains ports) <\/td>\n<\/tr>\n\n 113<\/td>\n Table 18 \u2013 Radiated emission test limits <\/td>\n<\/tr>\n \n 114<\/td>\n Annexes
Annex A (normative) Marking and identification of terminals of contactors, starters and associated overload relays
A.1 General
A.2 Marking and identification of terminals of main circuits
A.3 Marking and identification of terminals of overload relays
Figure A.1 \u2013 Main circuit <\/td>\n<\/tr>\n\n 115<\/td>\n Figure A.2 \u2013 Overload relays <\/td>\n<\/tr>\n \n 116<\/td>\n Annex B (normative) Special tests
B.1 General
B.2 Mechanical durability
B.2.1 General
B.2.2 Verification of mechanical durability <\/td>\n<\/tr>\n\n 118<\/td>\n B.3 Electrical durability
B.3.1 General <\/td>\n<\/tr>\n\n 119<\/td>\n B.3.2 Results to be obtained
B.3.3 Statistical analysis of test results for contactors or starters
Table B.1 \u2013 Verification of the number of on-load operating cycles \u2013 Conditions for making and breaking corresponding to the several utilization categories <\/td>\n<\/tr>\n\n 120<\/td>\n B.4 Coordination at the crossover current between the starter and associated SCPD
B.4.1 General and definitions <\/td>\n<\/tr>\n\n 121<\/td>\n B.4.2 Condition for the test for the verification of co-ordination at the crossover current by a direct method
B.4.3 Test currents and test circuits
B.4.4 Test procedure and results to be obtained
B.4.5 Verification of co-ordination at the crossover current by an indirect method <\/td>\n<\/tr>\n\n 122<\/td>\n Table B.2 \u2013 Test conditions <\/td>\n<\/tr>\n \n 123<\/td>\n Figure B.1 \u2013 Examples of time-current withstand characteristic <\/td>\n<\/tr>\n \n 124<\/td>\n Annex C (informative) Typical characteristics of starters
Figure C.1 \u2013 Typical curves of currents and torques during a star-delta start (see 3.4.4.1) <\/td>\n<\/tr>\n\n 125<\/td>\n Figure C.2 \u2013 Typical curves of currents and torques during an auto-transformer start (see 3.4.4.2) <\/td>\n<\/tr>\n \n 126<\/td>\n Figure C.3 \u2013 Typical variants of protected starters, combination starters, protected switching devices and combination switching devices <\/td>\n<\/tr>\n \n 127<\/td>\n Figure C.4 \u2013 Example of three-phase diagram of a rheostatic rotor starter with three starting steps and one direction of rotation (in the case whenall the mechanical switching devices are contactors) <\/td>\n<\/tr>\n \n 129<\/td>\n Figure C.5 \u2013 Typical methods and diagrams of starting alternating-current induction motors by means of auto-transformers <\/td>\n<\/tr>\n \n 130<\/td>\n Figure C.6 \u2013 Examples of speed\/time curves corresponding to cases a), b), c), d), e) and f) of 5.3.5.6.1 <\/td>\n<\/tr>\n \n 131<\/td>\n Annex D (informative) Items subject to agreement between manufacturer and user <\/td>\n<\/tr>\n \n 132<\/td>\n Annex E (Void) <\/td>\n<\/tr>\n \n 133<\/td>\n Annex F (normative) Requirements for auxiliary contact linked with power contact (mirror contact)
F.1 Application and object
F.1.1 Application
F.1.2 Object
F.2 Terms and definitions
F.3 Characteristics
F.4 Product information <\/td>\n<\/tr>\n\n 134<\/td>\n F.5 Normal service, mounting and transport conditions
F.6 Constructional and performance requirements
F.7 Tests
F.7.1 General
F.7.2 Tests on products in a new condition
Figure F.1 \u2013 Mirror contact <\/td>\n<\/tr>\n\n 135<\/td>\n F.7.3 Test after conventional operational performance (defined under Table 10)
Table F.1 \u2013 Test voltage according to altitude <\/td>\n<\/tr>\n\n 136<\/td>\n Annex G (informative) Rated operational currents and rated operational powers of switching devices for electrical motors
G.1 General
G.2 Rated operational powers and rated operational currents <\/td>\n<\/tr>\n\n 137<\/td>\n Table G.1 \u2013 Rated operational powers and rated operational currents of motors <\/td>\n<\/tr>\n \n 140<\/td>\n Annex H (normative) Extended functions to electronic overload relays
H.1 General
H.2 Terms and definitions
H.3 Limits of operation of control functions
H.3.1 General
H.3.2 Limits of electronic overload relay with main circuit under-voltage restarting function <\/td>\n<\/tr>\n\n 141<\/td>\n H.4 Test of the control functions <\/td>\n<\/tr>\n \n 142<\/td>\n Annex I (informative) AC-1 contactors for use with semiconductor controlled motor load <\/td>\n<\/tr>\n \n 143<\/td>\n Annex J (Void) <\/td>\n<\/tr>\n \n 144<\/td>\n Annex K (normative) Procedure to determine data for electromechanical contactors used in functional safety applications
K.1 General
K.2 Test requirements
K.3 Characterization of a failure mode
K.4 Failure ratios of a contactor
Table K.1 \u2013 Failure mode of contactors <\/td>\n<\/tr>\n\n 145<\/td>\n Table K.2 \u2013 Typical failure ratios for normally open contactors <\/td>\n<\/tr>\n \n 146<\/td>\n Annex L (normative) Assessment procedure for electromechanical overload protection used in safety applications and especially in explosive atmospheres
L.1 Application and object
L.1.1 Application
L.1.2 Object
L.2 Terms, definitions and symbols
L.2.1 Terms and definitions <\/td>\n<\/tr>\n\n 147<\/td>\n L.2.2 Symbols and abbreviations <\/td>\n<\/tr>\n \n 148<\/td>\n L.3 Procedure
L.3.1 General
L.3.2 Safety design process <\/td>\n<\/tr>\n\n 149<\/td>\n L.4 Requirements
L.4.1 General
L.4.2 Safety plan
Figure L.1 \u2013 Safety design process <\/td>\n<\/tr>\n\n 150<\/td>\n L.4.3 Design
L.4.4 Failure mode and effects analysis of the safety function <\/td>\n<\/tr>\n\n 151<\/td>\n L.4.5 Design plan
L.4.6 Verification
L.4.7 Function assessed
L.5 Documentation
L.5.1 Technical safety documentation
L.5.2 Safety instructions <\/td>\n<\/tr>\n\n 152<\/td>\n L.6 Example
L.6.1 architecture description
Figure L.2 \u2013 Typical structure of a thermal overload relay <\/td>\n<\/tr>\n\n 153<\/td>\n L.6.2 FMEA
Figure L.3 \u2013 typical structure of MPSD
Table L.1 \u2013 Severity <\/td>\n<\/tr>\n\n 154<\/td>\n Table L.2 \u2013 Occurrence
Table L.3 \u2013 Detection levels <\/td>\n<\/tr>\n\n 155<\/td>\n Table L.4 \u2013 Conclusion <\/td>\n<\/tr>\n \n 156<\/td>\n Table L.5 \u2013 Example of failure mode and effects analysis for thermal overload relay <\/td>\n<\/tr>\n \n 161<\/td>\n Annex M (normative) DC contactors for use in photovoltaic (PV) applications
M.1 Application
M.2 Object
M.3 Terms and definitions <\/td>\n<\/tr>\n\n 162<\/td>\n M.4 Classification
M.5 Characteristics
M.5.1 General
M.5.2 Rated impulse withstand voltage
M.5.3 Utilization category
Table M.1 \u2013 Rated impulse voltage levels for PV contactors
Table M.2 \u2013 Utilization categories <\/td>\n<\/tr>\n\n 163<\/td>\n M.6 Product information
M.7 Normal service, mounting and transport conditions
M.7.1 General
M.7.2 Ambient air temperature
M.7.3 Altitude
Table M.3 \u2013 Ambient air temperature conditions <\/td>\n<\/tr>\n\n 164<\/td>\n M.8 Constructional and performance requirements
M.8.1 Constructional requirements
M.8.2 Performance requirements
Table M.4 \u2013 Verification of rated making and breaking capacities \u2013Conditions for making and breaking corresponding to the DC-PV category <\/td>\n<\/tr>\n\n 165<\/td>\n M.8.3 Electromagnetic compatibility (EMC)
M.9 Tests
M.9.1 General
M.9.2 Type tests
Table M.5 \u2013 Conventional operational performance \u2013 Making and breaking condition corresponding to the DC-PV category <\/td>\n<\/tr>\n\n 166<\/td>\n M.9.3 Making and breaking capacities and conventional operational performance
M.9.4 Thermal cycling test
M.9.5 Climatic test
M.9.6 Dielectric test
Table M.6 \u2013 Overall scheme of test sequences <\/td>\n<\/tr>\n\n 167<\/td>\n M.9.7 Critical load current test
Figure M.1 \u2013 Critical current <\/td>\n<\/tr>\n\n 168<\/td>\n M.9.8 Mechanical properties
Table M.7 \u2013 Number of operating cycles corresponding to the critical load current
Table M.8 \u2013 Critical load current performance <\/td>\n<\/tr>\n\n 169<\/td>\n M.9.9 Degree of protection of enclosed contactors
M.9.10 EMC
M.9.11 Clearance and creepage distances <\/td>\n<\/tr>\n\n 170<\/td>\n Annex N (normative) Additional requirements and tests for equipment with protective separation
N.1 General
N.2 Definitions
N.3 Requirements
N.3.1 Test method for implementing protective impedance <\/td>\n<\/tr>\n\n 171<\/td>\n N.3.2 Touch current measurement
Figure N.1 \u2013 Protection by means of protective impedance <\/td>\n<\/tr>\n\n 172<\/td>\n Figure N.2 \u2013 Measuring instrument <\/td>\n<\/tr>\n \n 173<\/td>\n Annex O (informative) Load monitoring indicators
O.1 General
O.2 Indicators list <\/td>\n<\/tr>\n\n 174<\/td>\n Table O.1 \u2013 AC monitoring indicators list <\/td>\n<\/tr>\n \n 175<\/td>\n O.3 Uncertainty
Figure O.1 \u2013 Example of quantification of a process change <\/td>\n<\/tr>\n\n 176<\/td>\n O.4 Tests
O.4.1 Routine tests
O.4.2 Type tests
Table O.2 \u2013 Different possibilities authorized for verification of indicators <\/td>\n<\/tr>\n\n 177<\/td>\n Table O.3 \u2013 Reference for verification conditions
Table O.4 \u2013 Harmonic levels <\/td>\n<\/tr>\n\n 178<\/td>\n Annex P (normative) Short-circuit breaking tests of MPSD
P.1 General test conditions
P.2 Rated service short-circuit breaking capacity
P.2.1 General <\/td>\n<\/tr>\n\n 179<\/td>\n P.2.2 Test of rated service short-circuit breaking capacity
P.2.3 Verification of operational performance capability
P.2.4 Verification of dielectric withstand <\/td>\n<\/tr>\n\n 180<\/td>\n P.2.5 Verification of temperature-rise
P.2.6 Verification of overload releases
P.3 Rated ultimate short-circuit breaking capacity
P.3.1 General
P.3.2 Verification of overload releases <\/td>\n<\/tr>\n\n 181<\/td>\n P.3.3 Test of rated ultimate short-circuit breaking capacity
P.3.4 Verification of dielectric withstand
P.3.5 Verification of overload releases
P.4 Test of MPSD for IT system
P.4.1 General
P.4.2 Individual pole short-circuit <\/td>\n<\/tr>\n\n 182<\/td>\n P.4.3 Verification of dielectric withstand
P.4.4 Verification of overload releases
P.4.5 Marking <\/td>\n<\/tr>\n\n 183<\/td>\n Annex Q (normative) Co-ordination under short-circuit conditions between a MPSD and another short-circuit protective device associated in the same circuit
Q.1 Application
Q.2 Object <\/td>\n<\/tr>\n\n 184<\/td>\n Q.3 General requirements for the co-ordination of a MPSD with another SCPD
Q.3.1 General considerations
Q.3.2 Behaviour of C1 in association with another SCPD
Q.4 Type and characteristics of the associated SCPD <\/td>\n<\/tr>\n\n 185<\/td>\n Q.5 Verification of selectivity
Q.5.1 General
Q.5.2 Consideration of selectivity by desk study <\/td>\n<\/tr>\n\n 186<\/td>\n Q.5.3 Selectivity determined by test <\/td>\n<\/tr>\n \n 188<\/td>\n Figure Q.1 \u2013 Over-current co-ordination between a MPSD and a fuse or back-up protection by a fuse: operating characteristics <\/td>\n<\/tr>\n \n 189<\/td>\n Figure Q.2 \u2013 Total selectivity between MPSD and circuit-breakers \u2013 Case 1
Figure Q.3 \u2013 Total selectivity between MPSD and circuit-breakers \u2013 Case 2 <\/td>\n<\/tr>\n\n 190<\/td>\n Figure Q.4 \u2013 Back-up protection by a circuit-breaker \u2013 Operating characteristics \u2013 Case 1
Figure Q.5 \u2013 Back-up protection by a circuit-breaker \u2013 Operating characteristics \u2013 Case 2 <\/td>\n<\/tr>\n\n 191<\/td>\n Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" \n\n
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