Iec 60644 2009

2 ...7 6.4 Interpretation of the test results ...8 7 Information to be given to the user ...8 8 Selection of fuse-links for motor circuit applications and correlation of fuse-link charac

General

The withstand tests are type tests Both test sequences shall be carried out on the same fuse- link

The fuse-link shall be tested under the same test conditions as in 6.5.1.2 of IEC 60282-1

The values of test currents shall be KI f 10 for pulses simulating the motor starting pulses and

K for periods simulating the normal motor running, I f 10 being the pre-arcing current at

10 s The tolerance on both values shall be + 10 0 %

The duration of individual pulses shall be 10 s The tolerance on the 10 s periods, both pulses and off periods, shall be ±0,5 s

Tests shall be made at any convenient voltage and at a frequency from 48 Hz to 62 Hz

LICENSED TO MECON Limited - RANCHI/BANGALORE, FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.

Test sequence No 1

This test sequence shall comprise 100 cycles of 1 h as follows:

Test sequence No 2

This test sequence shall comprise 2 000 cycles of 10 min as follows:

Test sequences No.1 and No.2 are illustrated in Figure 1

Figure 1 – Diagrams of the test sequences

Interpretation of the test results

After completing each test sequence, the fuse-link must cool down, and there should be no significant change in its characteristics A measurement to confirm that the resistance values of the fuse-links remain consistent before and after testing indicates compliance with this requirement If there is uncertainty, an additional method involves applying a sustained current of K I f 10 to the cooled fuse-link until the fuse element melts The pre-arcing time must fall within the tolerances specified by the manufacturer for the pre-arcing time-current characteristic.

If fuse-links form part of a homogeneous series as defined in items d), e) and f) of 6.6.4.1 of

IEC 60282-1, the maximum and minimum current ratings only need be tested

When the same value of K is used for both maximum and minimum current ratings, it applies to all intermediate ratings in the homogeneous series However, if different K values are assigned to the maximum and minimum ratings, the K factors for intermediate ratings can be calculated through linear interpolation, as illustrated in Figure 2.

If a manufacturer assigns a higher value of K for an intermediate rating than that resulting from interpolation, this assigned value shall be proved by tests to the requirements of

M ax im um c urrent rat ing

Int erm edi at e c urrent rat ing

M ini m um c urrent rati ng

Figure 2 – Determination of K factor for fuse-links of intermediate rating of a homogeneous series

7 Information to be given to the user

Although in principle any high-voltage fuse-link can be used to protect motor circuits, there are advantages in selecting a fuse-link specifically designed for this application

For fuse-links intended to be used for motor circuit protection, the manufacturer shall state the

The K factor indicates the fuse-link's ability to endure cyclic overloads without deterioration It is essential to specify whether the K factor pertains to the minimum or the mean pre-arcing time-current characteristic.

The pre-arcing time-current characteristic of the fuse-link, adjusted by a factor K, establishes the overload curve boundary for a specified number of motor starts per hour.

8 Selection of fuse-links for motor circuit applications and correlation of fuse- link characteristics with those of other components of the circuit

Selection of fuse-links

The fuse-link is placed within the motor circuit it is designed to safeguard Certain ratings of the fuse-links, such as rated voltage and rated breaking current, are influenced by the system, while others, like rated current, are determined by the motor itself.

When choosing a fuse-link for a motor circuit application, it is crucial to consider the K factor, which accounts for the ability to endure repetitive starting conditions This factor should be applied to the pre-arcing time-current characteristic of the fuse-link to ensure optimal performance under these specific conditions.

The rated current of a fuse-link, defined by its capacity to continuously carry a specific current without surpassing a designated temperature rise, is often less critical when a motor is started direct-on-line In these cases, the selection of the fuse-link is typically guided by the previously mentioned criteria.

When fuse-links are housed within motor circuit equipment, it is essential to ensure that their rated current is higher than the motor's running current This excess should adequately account for the impact of the surrounding air temperature.

Assisted starting techniques effectively reduce starting currents, making the selection method generally applicable However, it is essential to consider the high transient currents that may occur during the transition between connections Additionally, since assisted starting permits the use of lower-rated fuse links, managing temperature rise during operation becomes a critical factor.

Co-ordination with other circuit components

Figure 3 illustrates a typical motor circuit application involving a motor, relay or relays

Inverse overcurrent protection, instantaneous overcurrent protection, and instantaneous earth fault protection are essential components in electrical systems These protections work in conjunction with contactors or other mechanical switching devices, as well as the cables and fuse-links, to ensure safe and reliable operation.

When selecting a motor, it is essential to consider its specific duty, which determines the full load current and starting current values Additionally, the duration and frequency of starts must be established To ensure adequate thermal protection for the motor, the characteristics of the associated inverse time overcurrent relay should be carefully chosen Furthermore, the selection of the switching device should be coordinated with the fuse-link to align with the chosen motor specifications.

The pre-arcing time-current characteristic of the fuse-link, as shown in Figure 3, must be positioned to the right of the motor starting current at point A when multiplied by the appropriate K factor.

The switching device must endure the conditions outlined by the operating characteristic curves, particularly at points D, B, C, and E It is crucial that the rated current of the fuse-link is selected to continuously handle the motor's running current without overheating, especially during assisted starting Additionally, the current at point B, where the fuse-link and overcurrent relay intersect, should be lower than the maximum breaking current of the switching device The rated minimum breaking current of the fuse-link must not surpass the minimum take-over current, which is the point where the switching device assumes breaking duty from the fuse If instantaneous protection is implemented, the take-over point will shift accordingly.

When considering B to C, it is crucial to acknowledge that the switching device may open at a current exceeding its rated maximum breaking current Additionally, the cut-off current of the fuse-link at the system's maximum fault current must not surpass the rated peak short-circuit withstand current (I p) of the switching device Ideally, the rated minimum breaking current of the fuse-link should be minimized, preferably matching or being lower than the motor's starting current (refer to IEC 60282-1, section 9.3.3.5) As illustrated in Figure 3, the entire withstand curve of the cable should be positioned to the right of the operating characteristic DBCE In cases where high ratings of fuse-link are required due to the motor's starting duty—such as prolonged starting times and frequent starts—the sections B, C, and E may shift to the right, potentially necessitating an increase in cable size.

NOTE In cases where the switching device can be tripped by operation of the fuse striker, reference should be made to IEC 60470[1] 1

1 Figures in square brackets refer to the bibliography

Time-current characteristic of the fuse

Rated maximum breaking current of switching device

For clarity, only the average characteristics are presented However, it is essential to consider manufacturing tolerances and the differences between the "cold" and "hot" characteristics of the circuit's various components in practice.

Figure 3 – Characteristics relating to the protection of a motor circuit

[1] IEC 60470, High-voltage alternating current contactors and contactor-based motor- starters

3 Caractéristique temps-courant des éléments de remplacement 17

8 Choix des éléments de remplacement utilisés sur des circuits comprenant des moteurs et coordination des caractéristiques des éléments de remplacement avec celles des autres composants du circuit 22

8.1 Choix des éléments de remplacement 22

8.2 Coordination avec les autres composants du circuit 22

Figure 1 – Diagrammes des séquences d'essai 20

Figure 2 – Détermination du facteur K pour les éléments de remplacement du courant assigné intermédiaire d'une série homogène 21

Figure 3 – Courbes caractéristiques pour la protection d'un circuit de moteur 24

SPÉCIFICATION RELATIVE AUX ÉL É MENTS

DE REMPLACEMENT À HAUTE TENSION DESTINÉS À DES CIRCUITS COMPRENANT DES MOTEURS

The International Electrotechnical Commission (IEC) is a global standardization organization comprising national electrotechnical committees Its primary goal is to promote international cooperation on standardization issues in the fields of electricity and electronics To achieve this, the IEC publishes international standards, technical specifications, technical reports, publicly accessible specifications (PAS), and guides, collectively referred to as "IEC Publications." The development of these publications is entrusted to study committees, which allow participation from any national committee interested in the subject matter Additionally, international, governmental, and non-governmental organizations collaborate with the IEC in its work The IEC also works closely with the International Organization for Standardization (ISO) under conditions established by an agreement between the two organizations.

Official decisions or agreements of the IEC on technical matters aim to establish an international consensus on the topics under consideration, as each study committee includes representatives from the relevant national IEC committees.

The IEC publications are issued as international recommendations and are approved by the national committees of the IEC While the IEC makes every reasonable effort to ensure the technical accuracy of its publications, it cannot be held responsible for any misuse or misinterpretation by end users.

To promote international consistency, the national committees of the IEC commit to transparently applying IEC publications in their national and regional documents as much as possible Any discrepancies between IEC publications and corresponding national or regional publications must be clearly stated in the latter.

5) La CEI n’a prévu aucune procédure de marquage valant indication d’approbation et n'engage pas sa responsabilité pour les équipements déclarés conformes à une de ses Publications

6) Tous les utilisateurs doivent s'assurer qu'ils sont en possession de la dernière édition de cette publication

The IEC and its directors, employees, agents, including its specialized experts and members of its study committees and national committees, shall not be held liable for any injury or damage, whether direct or indirect, arising from the publication or use of this IEC Publication or any other IEC Publication, nor for any associated costs, including legal fees and expenses.

8) L'attention est attirée sur les références normatives citées dans cette publication L'utilisation de publications référencées est obligatoire pour une application correcte de la présente publication

It is important to note that some elements of this IEC publication may be subject to intellectual property rights or similar rights The IEC cannot be held responsible for failing to identify such property rights or for not indicating their existence.

La Norme internationale CEI 60644 a été établie par le sous-comité 32A: Coupe-circuit à fusibles à haute tension, du comité d'études 32 de la CEI: Coupe-circuit à fusibles

Cette deuxième édition annule et remplace la première édition, parue en 1979, dont elle constitue une révision technique

Les changements majeurs par rapport à l’édition précédente sont les suivants:

• mise à jour des références normatives ;

Le texte de cette norme est issu des documents suivants:

Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant abouti à l'approbation de cette norme

Cette publication a été rédigée selon les Directives ISO/CEI, Partie 2

The committee has determined that the content of this publication will remain unchanged until the maintenance date specified on the IEC website at "http://webstore.iec.ch" in the data related to the publication in question On that date, the publication will be updated.

• remplacée par une édition révisée, ou

SPÉCIFICATION RELATIVE AUX ÉL É MENTS

DE REMPLACEMENT À HAUTE TENSION DESTINÉS À DES CIRCUITS COMPRENANT DES MOTEURS

La présente norme s’applique principalement aux éléments de remplacement utilisés avec des moteurs à démarrage direct sur des réseaux en courant alternatif à 50 Hz et 60 Hz

When using motors with indirect starting, this specification may also apply; however, it is important to pay attention to the assigned current of the replacement component (see section 8.1) and to consult the manufacturer of the replacement part.

Replacement elements that meet this specification are designed to withstand normal operating conditions and motor starting impulses They must comply with the requirements of IEC 60282-1.

Généralités

Les essais de tenue sont des essais de type Les deux séquences d’essais sont effectuées sur le même élément de remplacement

L’élément de remplacement doit être essayé dans les mêmes conditions d’essai que celles indiquées en 6.5.1.2 de la CEI 60282-1

The test current values should be KI f 10 to represent the starting impulses and KI f 10 6 for the motor's operating periods, with I f 10 being the pre-arc current at 10 seconds The tolerance for both values must be + 10 0 %.

La durée de chaque impulsion doit être égale à 10 s La tolérance sur les périodes de 10 s, tant impulsions que périodes d’arrêt, doit être de ±0,5 s

Les essais doivent être effectués à une tension convenable quelconque et à une fréquence comprise entre 48 Hz et 62 Hz.

Séquence d’essais n° 1

Cette séquence d’essais doit comprendre 100 cycles de 1 h comme suit:

– une période sans courant de 10 s;

– une période sans courant de 10 s.

Séquence d’essais n° 2

Cette séquence d’essais doit comprendre 2 000 cycles de 10 min comme suit:

– une période sans courant de 300 s

Une illustration des séquences d’essais n°1 et n°2 est donnée à la Figure 1

Figure 1 – Diagrammes des séquences d'essai

Interprétation des résultats d’essai

After completing each test sequence, the replacement component must be allowed to cool down Once cooled, there should be no significant changes in its characteristics No control is required until both test sequences are finished Measurements indicating that there is no substantial difference in the resistance values of the replacement component before and after testing provide assurance of compliance with this requirement If there are any doubts, an additional method involves subjecting the cooled replacement component to the test current f 10.

The K pendant must be maintained for a sufficient duration to induce its melting The pre-arc duration should remain within the tolerances of the time-current characteristics specified by the manufacturer.

If replacement components are part of a homogeneous series as defined in points d), e), and f) of 6.6.4.1 of IEC 60282-1, only those with the maximum and minimum rated currents are tested.

If the same value of K is set for both the maximum and minimum assigned currents, it is accepted that this value can also apply to all intermediate assigned current values within the homogeneous series If different values of K are established for

Licensed to MECON Limited in Ranchi/Bangalore for internal use only, as supplied by the Book Supply Bureau The maximum and minimum assigned currents, along with the corresponding K factors for intermediate assigned currents, can be determined through linear interpolation; refer to Figure 2.

If a manufacturer sets a value of K for an intermediate rated current that is higher than the value obtained from interpolation, this specified value must be validated through tests that comply with the requirements of Article 6.

Courant ass igné m ax im al

Courant ass igné i nt erm édi are

Courant ass igné m ini m al

Figure 2 – Détermination du facteur K pour les éléments de remplacement du courant assigné intermédiaire d'une série homogène

While any high-voltage replacement component can theoretically be used to protect circuits with motors, there are significant advantages to selecting a replacement specifically designed for this purpose.

For replacement components intended for circuit protection involving motors, the manufacturer must establish the K factor, which indicates the extent to which the replacement element can withstand cyclic overloads without deterioration It is essential to specify whether the K factor relates to the minimum or average pre-arc time-current characteristic.

The current-time characteristic of the prearc replacement element, with current values multiplied by factor K, establishes a limit for the overload curve based on a specified number of motor starts per hour.

8 Choix des éléments de remplacement utilisés sur des circuits comprenant des moteurs et coordination des caractéristiques des éléments de remplacement avec celles des autres composants du circuit

Choix des éléments de remplacement

The replacement element is integrated into the circuit that includes the motor it is designed to protect Certain assigned characteristics of the replacement element, such as rated voltage and rated breaking capacity, are dependent on the network, while others, like the rated current, are determined by the motor.

La capacité à supporter des conditions de démarrages successifs est un facteur important

When selecting a replacement component for use in a specific motor circuit, it is crucial to pay close attention to the K factor applied to the pre-arc time-current characteristic of the replacement element to account for the starting conditions.

The standard concept of assigned current, which is based on a replacement component's ability to continuously handle a specified current without exceeding a defined temperature rise, is typically of secondary importance during direct motor startup Replacement components for such applications are usually selected with reference to the aforementioned guidelines.

When replacement components are installed within equipment designed for circuits that include motors, it is essential to ensure that their rated current exceeds the motor's operating current This should include a sufficient margin to account for the impact of the surrounding air temperature (refer to Annex F of IEC 60282-1).

When using indirect starting methods that reduce starting currents, the aforementioned selection method is typically applicable However, it is important to consider the high transient currents that may occur during the transition from one connection to another with certain starting methods Additionally, since indirect starting often allows for the use of replacement components with lower rated currents, heating during operational conditions may become a critical factor.

Coordination avec les autres composants du circuit

Figure 3 depicts a typical motor circuit application, which includes a motor, one or more relays for functions such as inverse time protection against overcurrents, instantaneous protection against overcurrents, and instantaneous ground fault protection Additionally, the circuit features a contactor or another mechanical connection device, along with the cable and the replacement element itself.

The motor is selected based on the specific service it needs to perform, determining the full-load and starting current values Additionally, the duration and frequency of starts are established Consequently, the inverse time characteristic of the associated overcurrent relay is chosen to ensure proper thermal protection for the motor.

L’appareil de connexion est choisi en relation avec l’élément de remplacement pour être coordonné avec le moteur déjà choisi

In reference to Figure 3, it is important to note that: a) the pre-arc current-time characteristic of the replacement element, after being multiplied by the appropriate factor K, lies to the right of the motor's starting current at point A; b) the mechanical connection device must withstand the stresses defined by the operating characteristic curves shown in Figure 3, represented by points D, B, C, and E.

The replacement element's assigned current must be selected to continuously support the motor's operating current without abnormal heating, especially during indirect starts Additionally, the current at point B, where the time-current curves of the replacement element and the overload relay intersect, should be lower than the maximum assigned cutoff current of the connecting device The minimum assigned cutoff current of the replacement element must not exceed the minimum intersection current, particularly when the connecting device overrides the fuse's cutoff service at point B If instantaneous protection is provided, the intersection point shifts from B to C, necessitating careful consideration of the connecting device's ability to open under currents exceeding its maximum assigned cutoff current Furthermore, the limited cutoff current of the replacement element for the maximum fault current should not exceed the assigned peak withstand current (I_p) of the connecting device, and the minimum assigned cutoff current of the replacement element should be as low as possible, ideally at least equal to the motor's starting current.

According to section 9.3.3.5 of IEC 60282-1, as shown in Figure 3, the entire cable performance curve is positioned to the right of the DBCE operating characteristic When high assigned currents for replacement components are required due to the motor's starting nature, such as prolonged start durations and frequent starts, sections B, C, and E shift to the right, potentially necessitating an appropriate increase in cable cross-section.

NOTE Dans le cas ó l’appareil mécanique de connexion peut être déclenché par le fonctionnement du percuteur du fusible, il convient de faire référence à la CEI 60470[1] 1

1 Les chiffres entre crochets renvoient à la bibliographie

Caractéristique temps-courant du fusible

Relais de surcharge à temps inverse

Courant maximal de coupure assigné de l’appareil de connexion

To simplify, only the average characteristics are presented In practice, it is important to consider construction tolerances and the variations in characteristics between the cold and hot states of the different components in the circuit.

Figure 3 – Courbes caractéristiques pour la protection d'un circuit de moteur

[1] CEI 60470, Contacteurs pour courant alternatif haute tension et démarreurs de moteurs à contacteurs

Tiêu đề	Specification for High-Voltage Fuse-Links for Motor Circuit Applications
Trường học	International Electrotechnical Commission (IEC)
Chuyên ngành	Electrical Engineering
Thể loại	standards document
Năm xuất bản	2009
Thành phố	Geneva

Định dạng
Số trang	30
Dung lượng	1,03 MB