DRIWISA HIGH VOLTAGE CURRENT-LIMITING FUSES HIGH INTERRUPTING CAPACITY INDOOR AND OUTDOOR USE

Transcription

1 HIGH VOLTAGE CURRENT-LIMITING FUSE CATALOG

2 ! DRIWISA trademark is registered by and is protected by national and international law. The use of this trademark without written authorization by is a crime punishable by law. COPYRIGHT Rigths reserved. Partial or complete reproduction is prohibited. México, EDITION Edited by:

3 INDEX CONTENTS Page INTRODUCTION H-3 MANUFACTURING RANGE H-3 DESIGN AND CONSTRUCTION H-4 OPERATION H-6 DEFINITIONS H-9 Rated Current H-9 Interrupting Capacity H-9 (Maximum interrupting current) Minimum interrupting current H-9 Rated Current Selection H-10 Time-Current characteristic curves H-11 Rated Voltage H-15 Application on electric disconnecting switches H-15 ADVANTAGES H-16 USE AND HANDLING PRECAUTIONS H-16 TRANSPORTATION AND STORAGE H-17 MAINTENANCE H-17 INSTALLATION AND REPLACEMENT H-17 SELECTION H-18 TEMPERATURE AND ALTITUDE CORRECTION CHART H-22 SELECTION CHART I-1 General Specifications I-2 ELECTRICAL AND MECHANICAL SPECIFICATION TABLES Fuses (DRS) with striker pin for transformer, motor and cable protection I-3 Dual fuses (DRS) with striker pin for transformer, motor and cable protection. I-6 Fuses (DRK) threaded without striker-pin for capacitor protection I-7 Fuses (DRN) without striker-pin for potential transformer protection I-10 FUSE SELECTION CHART FOR TRANSFORMER PROTECTION I-11 H-1

4 Aspects, operation principles and basic parameters described in this manual, are usually applicable to all current-limiting fuses. The selection criteria, calculation factors and electrical and mechanical data, as well as Selection guide, specifications only apply to DRIWISA Current Limiting Fuses. If fuses from other brands are used, the technical aspects must be checked with the manufacturer, because not all fuses are the same. Fuse repair or rehabilitation is a non recommended practice by DRIWISA, since the only way to guarantee the reparation (electrical and mechanical) requires the contaminated sand to be substituted, fluoresces or radiography test on the porcelain tube, and the cut-element (silver strips) has to be replaced including the striker pin (wire). DO NOT RISK THE INSTALATION SAFETY AND THE LIVES OF YOUR WORKERS, ALWAYS USE ORIGINAL DRIWISA FUSES. H-2

5 FOREWORD: Current-limiting fuses are devices to protect high voltage systems against short-circuit. They provide protection against thermic and dynamic damages that would occur in case of a short-circuits or overloadings more than the minimum interrupting capacity I3. The DRIWISA high voltage and high interrupting capacity current-limiting fuses are "back-up" fuse type, according to the IEC and NMX-J standard definitions and they are able to interrupt any current above the minimum interrupting capacity I3. Currents between the rated current In and the minimum interrupting capacity I3 are not interrupted safely. DRIWISA fuses are designed and manufactured according to international standards IEC , DIN 43625, VDE 0670 part 4, and NMX-J To obtain better results they can be used with Load Break Switches type LDTP, as well as with low voltage protection devices. Thanks to their short-circuit current-limiting characteristic, the short-circuit current is interrupted before the first half-cycle of the current wave reaches its natural maximum value (Figures 3 and 4). High interrupting capacity is obtained thanks to an optimum design that allows a uniform distribution of the developed energy during interruption, to the excellent materials and finish used, the care, the precision in the manufacturing and the strict quality assurance system. DRIWISA fuses are environmentally friendly protection devices as they keep the fuse elements inside that work under short-circuit conditions. They are mainly used as protection devices for transformers, motors, capacitor-banks, underground cables, overhead lines, potential transformers and other substation devices, including air insulated substations, SF6 switchgears or RMU, installed in fuse-holders types SP, DSP, EFS or DFS, load break switches types LDTP or LFST or in non-load switches types DTP or FST. For further information consult the corresponding selection guides on the Indoor Service and Outdoor Service equipment catalogs. The fuse s internal elements are high quality manufactured and it helps to avoid ageing of the material, so they are maintenance free. The routine test procedure includes measured ohmic resistance in each fuse, to prove their rated intensity. According to the NMX-J and IEC " It is advisable to replace all three fuse-links when the fuse-link on one or two phases of a threephase circuit has operated, unless it is definitely known that no over-current has passed through the unmelted fuse-links. MANUFACTURING RANGE: DRIWISA fuses range from 2.4 to 38 kv; their rated currents are described in Table 1, the types DRS, DRN and DRK are manufactured in the following versions: For indoor service: types: DRS For outdoor service: types: DRS...F "F" ending-code For capacitor-banks: types: DRK indoor service For potential transformers: types: DRN H-3

6 RATED MAXIMUM RATED VOLTAGE (kv) CURRENT AMP DRIWISA FUSE MANUFACTURING RANGE = DUAL AND SIM PLE FUSE VERSION TABLE 1 = DUAL FUSE DESIGN AND CONSTRUCTION: The fuse design is based on a several compartments system or a series of arcing chambers, where the voltaic arc produced by the fusion of the fuse link is extinguished. Fuse links, formed by one or several 99.9 % pure silver strips, are uniformly wound over a star shaped strip-holder (star-shaped body) built out of steatite (a ceramic material with great mechanical and thermal resistance). Due to its tooth edge design, the star-shaped body guarantees the fuse links safe and firm position. The star-shaped body and the fuse links are put into a porcelain tube that is the cylindrical body of the fuse, thus forming the series of arcing chambers. In every one of these arcing chambers, a part of the voltaic arc produced by the fusion or evaporation of the fuse link when a short-circuit occurs, is started, developed and extinguished. This process is described further on. Therefore the fusion and interrupting process is carried out without the influence of external factors. Fuse links have a group of precise holes regularly spaced lengthwise, calibrated according to each fuse feature, which constitutes a reduction in the conduction cross-section. When a short-circuit current is flowing, it is in these zones where the element fusion is produced and the voltaic arc during the first part of the current wave is established. Type and number of parallel connected silver strips depend on the fuse rated current. H-4

7 According to the above mentioned, the uniform distribution of the voltaic arc and the resulting voltage of the fuse operation is assured. The high interrupting capacity and the rated current wide range available, are mainly the result of these design features which allow the dissipation of the thermic energy generated during the fusion and evaporation process distributed evenly. The fuse is filled with sand of specific granulometry and formulation, thus providing the proper environment for voltaic arc cooling and quenching through the absorption and dissipation of the generated heat and condensation and solidification of the evaporated metal. Figure 1 Internal and external part of the DRIWISA fuse. Figure 1 shows a fuse chambers formed between the silver strips and the star-shape body. Different from other designs with silver wire, the energy distribution takes places lengthwise along the fuse body and not in just in one breaking point as done with wire. The star shaped strip-holder (star-shaped body) tooth edge design, is another difference which guarantees the safe and firm position of the silver strips, wherefore other designs have a flat porcelain body and do not guarantee the firm position of the strip. Fuse ends have silver coated electrolytic copper caps which are connected inside to the silver strips ends. DRS and DRS...F fuse types have a mechanical indicator which operates through a stored spring preloaded energy system with a striker pin that emerges from a fuse end when the fuse operates with a force of 120 N (12 Kg-force) and a shift of 35 mm. Figure 2 shows the mechanical indicator force-displacement characteristic. In accordance with IEC and NMX standard classifications, the striker pin of DRIWISA fuses, is classified as heavy duty (strong) type, and exhaustive tests have demonstrated that it is capable of activating the DRIWISA disconnector switches or other brands. H-5

8 FIGURE 2 Figure 2 Mechanical indicator force-displacement characteristic. DRIWISA fuses work satisfactorily in any mounting position, horizontal or vertical. In every case resin is used as a seal between the caps and the porcelain tube, to assure great resistance and long life sealing, waterproof and resistant to most severe and extreme atmospheric conditions. For outdoor fuses, additionally a special welding between the caps and lids is used to offer an optimum sealing. Installations with a high degree of humidity, coastal, tropical or rainy zones, it is recommended to use outdoor fuses (type DRS...F) even when installed indoors. In regard to their electrical, dimensional and mechanical characteristics (diameters, lengths, striker pin operation force, etc) DRIWISA fuses are manufactured in accordance with international IEC, DIN, VDE and NMX standards. For further details, consult the catalog Selection Guide (Section I) which contains the specifications and mechanical and electrical data. OPERATION: OPERATION PRINCIPLE: When a short-circuit condition occurs in an electric network, very appreciable thermic and dynamic effects are produced because of the high current values. The interruption of these currents in the shortest time possible is very important, avoiding or at least minimizing damages caused by dynamic stresses and overheating of conducting parts. Current-limiting and high interrupting capacity fuses are used as protection against short-circuit currents. The importance falls on the current-limiting effect, which is the fuse capacity to interrupt a short-circuit current before it reaches its maximum peak value, by limiting the let-through current value I D to the breaking current or fusion current I S which is considerably less than the non-limited short-circuit current (prospective current) I k shown in figure 3 with a dotted line and which corresponds to the short-circuit current available at the point where the fault occurs. Figure 3 shows the current and voltage behavior during a short-circuit current and the interrupting process. H-6

9 I k " I S I D I D = I S t S t L short-circuit prospective current (in case the fuse does not exist) (rms value) fusion current (peak value) let-through current (peak value) short-circuit current limited by the fuse pre-arcing time (fusion time) arcing time FIGURE 3 Short-circuit current interrupting process in a current-limiting fuse When the short-circuit begins, a minimum resistance opposes the flow of the current I D thus increasing at the same time the current I k and starting the temperature elevation process in the fuse link (silver strips). When they reach the I S value, (fuse breaking current or fusion current) the fuse link melts and interrupts the circuits at several points, with multiple voltaic arcs showing up, whose length increases quickly with the material is melting. Voltage increases very fast from the moment of the fusion, reaching a maximum (interruption voltage) and the current is limited to the I S value. At this moment the current stars its decreasing process. The limiting process is therefore the result of the insertion of the voltaic arcs resistance at several points from the fusion. When arcs turn cold as a consequence of the surrounding sand, consequently the conductivity is reduced and therefore, the resistance to the current flow increases quickly. The current decreases gradually at the same time as the voltage. Near the next zero voltage point, the voltaic arcs are extinguished and the current remains totally interrupted. The events described occur within the first half cycle of the short-circuit current, meaning, in less than 8 to 10 milliseconds. H-7

10 Formation of multiple voltaic arcs at the fuse length is a result of DRIWISA fuses special design which gives a even voltage distribution and the great amount of energy (heat) generated during this short process, thus preventing the possibility of arc reignition. Figure 4 shows the DRIWISA current-limiting fuse characteristics, indicating the let-through current maximum value I D equal to the fusion current I S with regard to the prospective short-circuit current rms value ( I k ) for fuses from 6 to 500 A. FIGURE 4 Maximum let-through current I D referred to the short-circuit prospective current I k Line A-A'represents the maximum asymmetrical peak current that will show up in the circuit if there is no fuse. The value of 1.8 x 2 corresponds to the maximum asymmetric value possible in the network, which represents the most critical condition. The declining lines correspond to every fuse rated current to mark the maximum let-through current I D (which corresponds to the fusion current I S ) in relation to the short-circuit prospective current I k. For example, for a short-circuit prospective current of I k = 20 ka (rms), if the current-limiting fuse is not there, the let-through current reaches I D = 1.8 x 2 x 20 ka = 50.9 ka peak. With a 32 A fuse this value is limited to only I D = I S = 4 ka peak within an operation time less than 10 milliseconds. It is important to consider that for low currents, for which the fusion time is long (including times over one cycle), the fuse does not act as a current-limiting fuse. Fuses will show their current-limiting characteristic only from a current value where the I D peak is the same as the I S. From this current level the fuse will operate as a current-limiting fuse (on the right side of the A-A'line in Figure 4). The point where the line corresponding to I S of every fuse meets with the A-A'straight line, defines the short-circuit current value from which the fuse operates as current-limiting over the abscissa (X). If the short-circuit current is lower, the fuse will not operate as a current-limiting fuse. For example, a 75A fuse will operate as a current-limiting fuse from approximately 2000 A of short-circuit value. H-8

11 BASIC DEFINITIONS: RATED CURRENT (I n ): The rated current is the maximum current value that the fuse can conduct for an indefinite amount of time without reaching fusion, but generating an energy that can be dissipated by the fuse. INTERRUPTING CAPACITY ( I 1 ) (MAXIMUM INTERRUPTING CURRENT) : The interrupting capacity (maximum interrupting current) I 1 corresponds to the maximum short-circuit current that the fuse is capable of interrupting safely. The interrupting capacity (maximum interrupting current) of DRIWISA fuses lies above the short-circuit currents usually available in electric networks. Nevertheless it is recommended to verify the short-circuit current of the network when selecting a fuse. The corresponding Selection Guides specify the maximum interrupting capacity (ka) for each type of fuse. When the short-circuit power is specified instead of the short-circuit current, the ratio between them is deduced from the following formula: P short-circuit = kv net x ka short-circuit x 3 MINIMUM INTERRUPTING CURRENT ( I 3 ): For values above the rated current I n, the fusion times are very long and they decrease at the same time the current increases (Figure 5). In this range (In and I3), heat dissipation capacity is lower than the heat generated inside, therefore severe thermic stresses that may damage the fuse occur. While the current increases, the fusion times are reduced until a point where the fusion occurs in a relatively short time (milliseconds), before thermic stresses and damages to the fuse occur. This current value is called the minimum interrupting current I3 and corresponds to the lower limit of current ranges that the fuse may satisfactorily interrupt. FIGURE 5 Typical Time-Current curve for current-limiting fuse Considering the above mentioned information, the minimum interrupting current value ( I 3 ) is defined in each time current curve. Currents below this value ( I3 ) operation for long periods of time are not recommended, because the current (overcurrent) does not have enough magnitude to produce the fusion, but is enough to produce excessive heating, modifying the fuse links characteristics and causing damages that reduce its ability to interrupt a future event. Therefore current-limiting fuses must not operate for long periods of time in the range of currents higher than the rated one ( In ) and lower than the minimum interrupting current ( I 3 ). However, if currents are higher than I 3, the fuse operation is quick, sure and defined. H-9

12 Even though the fusion process is based on known physical principles and laws, when currents are higher than I n (overcurrents) and less than I 3 or overcurrents of an intermittent type, there are difficulties in analyzing and evaluating the fusion process, because the behavior of the fuse will depend on its magnitude and duration, as well as on the periods between these overcurrents, during which the fuse is able to return to a normal regime or return to its cold state. If an overcurrent lasts a relatively long time and then stops, it can start the fusion process or reach the amalgamating condition with a rise in temperature due to energy dissipation during that period of time, changing the fuse links characteristics in a significant way, these are later subject to a new overcurrent regime or short-circuit, the fuses will react in a different way as to the standard characteristic, producing first heating or inexplicable interruptions and then a reaction completely out of specification. Figures 7 and 8 show the DRIWISA fuse time-current characteristic for the range of available rated currents in the manufacturing program, it can be seen that the minimum interrupting current I 3 (beginning at the dotted line) for fuses with rated currents up to 63 A, is about 2.5 times higher than the fuse rated current I n, for rated currents higher than 63 A, the minimum interrupting current I 3 is about 3 times the fuse rated current I n, while for fuse rated currents of 200 A and higher, it corresponds to 4 times the rated current I n. RATED CURRENT SELECTION ( I n ): FIGURE 6 Current-limiting fuse operation zones To avoid fuse operation within the overload range, the fuse rated current I n is selected with an overdimensioned factor according to the equipment being protected, which for example, when the transformers are between 1.6 and 2 times the circuit rated current. This way the fuse will be able to hold up with the magnetization currents (inrush) and even if the transformer works within an overload regime, the fuse will not be exposed to such operation, because the transformer high thermic capacity is higher than the fuse capacity. Appling this factor, it will be possible to coordinate protection with other devices such as overcurrent relays, phase fault relays, etc, and protection elements on the low voltage side, for example, fuses, thermo magnetic switches and other protections. Any current higher than I 3, will be interrupted in a time no longer than 10 to 100 sec., according to the corresponding curve in Figures 7 and 8. For a fast transformer protection fuse selection you can use the fast-track tool available on our website TIME-CURRENT CHARACTERISTIC CURVES: Graphs in Figures 7 and 8 correspond to DRIWISA fuses time-current performance and represent the response curves under cool conditions, without preloading, at a surrounding temperature of 20 C, with a tolerance margin of ± 20%, according to the IEC and NMX-J-149-1, for operating times longer than 0.01 sec. Graphs in Figure 9 correspond to the I 2 t characteristic (Joule integral) applicable to operating times lower than 0.1 sec. H-10

13 FIGURE 8 DRIWISA fuse time-current characteristic curves. For fuses from 1 to 6 A H-11

14 DRIWISA HIGH VOLTAGE CURRENT-LIMITING FIGURE 9 DRIWISA fuse time-current characteristic curves. For fuses from 6 to 500 A H-12

15 FIGURE 10 DRIWISA fuses I 2 t characteristic curve for operation times less than 0.1 sec H-13

16 The tight tolerance in the fuse links lineal resistance and a strict quality assurance during the manufacturing process guarantee the characteristic curves repeatability. Applying the overdimension factors and following the selection criteria according to the application, the probability of overloading in the fuse above the rated current I n is low. However, based on the knowledge of the network, the probability of overloads with currents higher than I n but less than I 3 during longer periods of time should be taken into consideration and protected by other devices, such as overcurrent relays connected to disconnecting devices like switches or loadbreak disconnectors. The oscillogram in Figure 10 shows the current performance and the voltage during a short-circuit interruption when a DRIWISA fuse type DRS07/100 with a 12 kv maximum rated voltage and 100 A rated current are subjected to a short-circuit prospective current of I k = 63 ka rms. The current-limiting effect can be deduced when the maximum let-through current I D reaches 15 ka peak that corresponds to the fuse fusion current I S, while the current that would have flown in the test circuit, replacing the fuse with a very low resistance conductor, would have reached a value of ka peak of the maximum asymmetrical peak current ( 1.8 x 2 x 63 A = ka peak ). Ve I P I D I D = I S Recovery voltage Short-circuit prospective current (rms value) Maximum let-through current Breaking current (fusion current) FIGURE 10 Interruption of a 63 ka rms short-circuit current with a fuse type DRS07/100 In accordance with the international standards IEC , VDE 0670 and NMX-J-149-1, the recovery voltage (Ve) at a system frequency is 87% of the fuse maximum rated voltage (V O ). Therefore, in the example shown in Figure 10 the result is: V e = 0.87 x V o = 0.87 x 12 kv = 10.5 kv H-14

17 OPERATION VOLTAGE ( V n ): The interrupting voltage or maneuver voltage generated during the arc extinction process and interrupting currents with a high grade of inductance, is of special interest. The transient voltage during the interruption process must not exceed the insulation levels coordinated in the network, because it would provoke trouble mainly at the insulation of other components of the system, among others, at arresters installed on the line. For this reason it is important to use fuses with a rated voltage in agreement to the network voltage. When using a fuse with less rated voltage in regard to the network voltage, problems to manage the increasing gradient voltage will arise, while using one with higher rated voltage and consequently higher interruption voltage would cause a higher increasing gradient voltage and would consequently create problems with the insulation of other equipments in the network system. In multiple tests accomplished on DRIWISA fuses, the highest arc interruption voltage value found was of V U = 1.95 x 2 x V O = 2.76 x V O. This value is considerably lower than those admitted by the standards in table 2. Consequently, using fuses with rated voltages according to network voltages does not provoke damages to the insulation of equipments connected to the load side, such as transformers, switches, substations, motors, etc. and avoiding the arresters operation. Table 2 lists the maximum arc interruption voltages admissible for high voltage fuses in accordance with international standards IEC 60282, VDE 0670 and NMX-J FUSE RATED SYSTEM RATED MAXIMUM MANEUVER VOLTAGE VOLTAGE (MEXICO) VOLTAGE kv rms kv rms kv peak Also defined as maximum interruption voltage TABLE 2 Maximum interruption voltage levels corresponding to the fuses rated voltage DRIWISA fuses can be installed in three-phase networks where the service voltage does not exceed the fuse rated voltage. In one-phase networks the service voltage must not be higer than 87% of the fuse rated voltage. In other cases, the voltage fuse selection must be such as that the maximum interruption voltage (maneuver voltage) does not exceed the maximum voltages established for the network (see Table 2). APPLICATION WITH LOAD-BREAK SWITCHES: Using current-limiting fuses in combination with DRIWISA load-break switches, three-pole group operated with automatic operation and auxilliary trip type LDTP, an economical and reliable connection and disconnection equipment is obtained. In this case, minimum interrupting current values I 3 may be considered lower ( from 1.8 to 2 times the fuse rated current I n ). This is because the fuse s striker pin response, which in case of being used with load-break switches, provokes the operation of the tripping-mechanism and the three phases open simultaneously. H-15

18 This way, when the first fuse acts, the disconnector switch operates opening the three poles, preventing a two-phase operation, and just in the phase where the fuse operated, the Load disconnector switch opens with a higher current than the other two phases. This current does not affect the switch because the fuse operation time is designed to interrupt the short circuit during the first stage, working the striker pin in a second stage and opening the switch in the third stage. During the interruption of the remaining phases, the disconnector switch is not subject to stress because it only has to interrupt the rated and voltage current of the net. If the other fuses have started their fusion process, the arcing currents are limited and isolated. In accordance with the IEC and VDE standards, the extreme operation condition of the unfused load-break switch, an inductive power factor = 0.7 (cos φ = 0.7) is specified. However, under short-circuit conditions, for instance, at the transformer secondary terminals, the value of cos φ can be considerably lower, around 0.1. However, when using a combination of fuses with a DRIWISA load-break switch, the switch has to disconnect at a lower current value due to the fuse currentlimiting characteristic and a power factor within its rated range, thanks to the fuse s high arc resistance. The use of fuses with a striker pin, in combination with load-break disconnector switches, is recommended for its excellent features and behavior in case of short-circuits. This is why many Electric Utility companies around the world use and specify DRIWISA fuses with striker pin to operate three-pole load-break disconnector switches. ADVANTAGES: DRIWISA fuse s high interrupting capacity guarantees a safe operation. Their current-limiting characteristic guarantees minimum damage to the network and other equipments due to dynamic and thermic short-circuit current effects. Due to their time-current characteristic, DRIWISA fuses, which are used for transformer or motor protection, do not show untimely fusion or fuse link degradation if they are selected according to the corresponding recommendations. For outdoor service fuses, a special welding between covers and caps is used in order to offer good protection against humidity. Cost saving when the same kind of fuses can be used in networks that have increased their short-circuit power. DRIWISA fuses are manufactured in a wide range of operation currents and voltages to meet any need. DRIWISA fuses are dimentionally standardized which makes selection and replacement easy. USE AND HANDLING PRECAUTIONS: The following precautions must be taken into consideration when handling and using fuses: - Water or humidity must not penetrate the fuse because the high temperatures reached when fusion takes place will provoke the abrupt generation of steam which can cause an explosion. - Handle fuses with precaution, avoid breakage of the porcelain and denting of the caps. If this happens, DO NOT USE THE FUSE, SERIOUS HAZARDS OR INJURIES MAY OCCUR. - Fuse copper caps are silver-plated to give them excellent conductivity and assure good electrical contact. DO NOT USE SANDPAPER OR STEEL WOOL TO CLEAN THE CAPS IF THEY ARE DIRTY OR IF THEY HAVE TURNED BLACK, this does not affect their electrical conductivity features. Use a soft, slightly damp cloth with silver cleaning solution that does not contain any abrasive or aggressive materials. - Do not place metallic or metallized labels on the fuse body, this may provoke external arcs, because the dielectric distance in the air between the caps is reduced. - NEVER USE Fuses repaired or rehabilitated because they do not guarantee the ability to operate under short-circuit conditions again. - When buying non-original or repaired fuses, keep in mind the equipment, installations and personnel that they will protect and remember that THE CHEAPEST COULD BE THE MOST EXPENSIVE". - Even when just one fuse has operated in a three-phase system, it is necessary and highly advisable to replace all three fuses, since the unmelted fuses may have internal damage if the fusion process (pre-arcing) has begun. This will cause problems later, such as inexplicable temperature elevations or unwanted interruptions. This recommendation is contained in the international standard IEC " It is advisable to replace all three fuse-links when the fuse-link on one or two phases of a three-phase circuit has operated, unless it is definitely known that no over-current has passed through the unmelted fuse-links. H-16

19 TRANSPORTATION AND STORAGE: During transport of DRIWISA fuses, avoid strikes that can break or crack the porcelain fuse body or dent the caps. For indoor service fuses, getting wet or exposure to humid environments must be avoided, for the reasons stated in previous lines. When receiving new fuses, inspect them before storage, informing the Authorized Distributor or the factory of any problem. Fuse storage must be done in a closed, cool and dry place. Do not store them in places where there are vibrations, moisture or dust. Keep the fuses inside their original package on a shelf in order to keep them safe from falling and do not stack more than 5 boxes per pile. MAINTENANCE: DRIWISA high voltage and high interrupting capacity fuses do not require any maintenance. However, it is recommended that after the fuse operation, in a three-phase system, replace all three fuses, even when only one fuse has blown, because the others could have been subjected to thermic stress that may have caused internal damages and then later cause problems such as inexplicable temperature elevations or unexpected and unexplained interruptions. This recommendation is contained in the international standard IEC In cases of high or prolonged overloading in the circuit protected by fuses, it is recommended to have the fuses checked in our factory or with any Authorized Distributor, since this overloading may have caused irreversible thermic damages that modify and demote its original characteristics. It is highly advisable, in all cases, to be equipped with a set of at least 3 spare fuses for emergency cases. These fuses must be of the same characteristics to those installed. Keep them according to the instructions given in the section "transportation and storage". Fuse copper caps are silver-plated to give them excellent conductivity and assure a good electrical contact. Do not use sandpaper or steel wool to clean the caps if they are dirty or if they have turned black, this does not affect their electrical conductivity features. Use a soft, slightly damp cloth with silver cleaning solution that does not contain any abrasive or aggressive materials. Do not place metallic or metallized labels on the fuse body, this may provoke external arcs, because the dielectric distance in the air between the caps is reduced. NEVER USE Fuses repaired or rehabilitated because they do not guarantee the ability to operate under short-circuit conditions again. INSTALLATION AND/OR REPLACEMENT: It is recommended to follow the these instructions when installing or replacing fuses: A) ACCOMPLISH THE SAFETY PREPARATIONS: 1) Use special pliers for handling high voltage fuses ( DRIWISA type DW-018) 2) Use insulating gloves for high voltage. 3) Use a facemask made of insulating material. 4) Have cable, hook stick and equipment ready to connect to ground. 5) Have a sand bed ready where fuses can be placed. 6) In front of the equipment which contains the fuses, place an insulating platform for high voltage or a wooden platform with an insulating rug and stay on it during the operation, more so if the environment is humid. 7) If working in branch circuits or remote substations, place placards on the main substation or switch to let everyone know that someone is working there. B) THINK FIRST AND THEN ACT, remember that when working with high voltage, the FIRST MISTAKE may be THE LAST ONE. 8) Disconnect the high voltage supply: 8.1) Be sure that the main load-break disconnector or main switch is open. If not, open it. 8.2) Open the non load isolator switch. 8.3) Connect the grounding switch ( If you have this kind of equipment). 9) Open the cabinet door; stay strategically where the door does not hit you, or receive projections from inside. H-17

20 PRECAUTION: FUSES MAY REACH HIGH TEMPERATURES, SO WHEN THE CABINET DOOR IS OPENED, THEY CAN RECEIVE A THERMAL IMPACT THAT MAY CRACK OR MAKE THE PORCELAIN TUBE EXPLODE. THEREFORE LET THE FRESH AIR ENTER SLOWLY. 10) Connect the ground cable (use the correct length of cable and a hook stick) to the substation's grounding bus bar or to grounded structures, and then to the phases (If you don t have a grounding switch integrated to the equipment). 11) Find out and determine what caused the fuse blow, it can be a short-circuit or an overload. Eliminate the trouble, remove the remains and make a general cleaning. 12) Verify the condition of the equipment and installations. 13) Inspect the new fuses and make sure they do not show mistreatment, cracks or fissures, check that the porcelain tube is not broken, grooved or scratched, nor dented the caps. If the above mentioned things happen, do not use them, because their use is very risky. Verify that the fuse striker pin is in its correct position inside the cap. 14) Fuse copper caps are silver-plated to give them excellent conductivity and assure a good electrical contact. DO NOT USE SANDPAPER OR STEEL WOOL TO CLEAN THE CAPS IF THEY ARE DIRTY OR IF THEY HAVE TURNED BLACK, this does not affect their electric conductivity features. Use a soft, slightly damp cloth with silver cleaning solution that does not contain any abrasive or aggressive materials. Do not place metallic or metallized labels on the fuse body, this may provoke external arcs, because the dielectric distance in the air between the caps is reduced. 15) Remove the old fuses with pliers DW-018 and replace them with DRIWISA fuses of the same characteristics: Type, rated voltage and rated current. Never use fuses of different brands, different types, different rated voltage or different current (even if they are of the same brand, since their characteristics are not the same) in the same circuit. In three-phase systems it is recommended to replace all three fuses even when only one has blown since the others may be damaged and cause problems later (IEC and NMX-J-149-1). PRECAUTION: FUSES MAY STAY HOT, PLACE THEM ON THE SAND BED, LETTING ENOUGH TIME PASS BEFORE TOUCHING THEM WITH BARE HANDS. 16) If the fuses are installed in load-break disconnector switches, verify the operation of the trip mechanism. 17) Place the new fuses carefully, making sure the clip assemblies make the proper contact with the fuse caps. When inserting the fuses in the clip assemblies, apply pressure to the ends and not to the middle of the fuse. Do not hit the fuse. 18) Remove all the tools that have been used and verify that no tools remain behind in the cabinet. 19) Disconnect the grounding switch or the ground connections, whatever the case may be. 20) Close the cabinet door, connect the non-load isolator switch and connect the high voltage supply. 21) When the fuse operation is caused by overloads, verify the load calculations and if necessary ask for three new fuses at the adequate rated current according to the new calculation. SELECTION: When selecting current-limiting fuses always consider the following factors: - Network rated voltage - Interrupting capacity - Installation altitude - Fuse rated current, according to application - Coordination with other protections - Type of service (indoor or outdoor) - Dimensions - Availability of spare parts, service and technical assistance - Safety and reliability : always use DRIWISA fuses H-18

21 Fuse selection must be done according to the equipment it will protect because the selection criteria is different for each application. It is recommended to use the selection tools available in our web page fast-track section. For transformer protection, to establish selection and coordination with protection on the low voltage side, it is necessary to refer to the high voltage fuse timecurrent characteristic curves, and to the curves of the devices and/or fuses on the low voltage side. Sometimes, for big transformer protection, it is necessary to use a two-per-phase fuse arrangement to reach the required rated current value. For motor protection it is required to know the starting time, the maximum starting current, and the motor starting frecuency to select the correct fuse. For more information please contact the DRIWISA sales department or an authorized distributor. The Capacitor and the capacitor-bank protection are of special importance, because of their increasing use, they have to keep the power factor within the acceptable limits and the relative rank of difficulty for its adequate protection, since connection currents reach, in many cases, levels very close to those of shortcircuit. In the fuse selection for networks and circuits with high probabilities of high overloadings which therefore require fuses with high current rates, we remind you that these must be used for protection against short-circuits and not for protection against overloading. Requirements for specific arrangements in networks have to be calculated in detail by the customer to control and/or verify the continuous load regime over the fuses, the interruption current, and the fuse interrupting capacity. All data corresponding to voltage, current and interrupting capacity given in this Catalog, are referred to installation heights of up to 1000 m above sea level and an environment temperature of up to 40 C. In any case, once you have selected the correct fuse for its application, consider the installation altitude correction factors included in Table 3, in the fuse rated current as in the interrupting capacity and rated voltage reduction. If it is calculated with the altitude correction in the rated current, do NOT use the temperature rising correction and vice versa. In some cases, a temperature correction factor should be additionally considered, in those cases, when the fuses are installed inside cabinets or switchboards with little ventilation and/or high temperatures, in accordance with Table 4. When there are several sizes of fuses for a specific rate of current, it is advisable to consider the future installation growth (greater rated current) or the increase of short-circuit capacity, this means to verify the selected fuse size there are larger rated currents or interrupting capacities, in such a way that when selecting them, the size chosen allows an increase in capacity, by means of just changing fuses for others of greater current or interrupting capacity when this growth is required. Fuses must have a rated voltage equal to or greater than the highest system voltage between phases, when they are used in three-phase systems with the neutral firmly grounded or with the neutral connected through an impedance or resistance. When using fuses in systems with isolated neutral (not grounded), the rated voltage should be at least 1.15 times the highest system voltage between phases. When fuses are used in one-phase systems, it s rated voltage should be at least 1.15 times greater than the voltage between phase and ground. H-19

22 CORRECTION FACTORS FOR INSTALLATION ALTITUDE AND TEMPERATURE: Installation altitude Correction factor Correction factor Correction factor (meters over sea level) for rated current for voltage and for temperature interrupting capacity rising 0 to to to to to to to to to to TABLE 3 Altitude correction factors according to international standards Operation Correction factor Temperature for fusion time ( C ) - 20 to to to to to to to to TABLE 4 Correction factors by temperature DRIWISA fuses are manufactured in a range from 2.4 to 38 kv in series DRS, DRN, and DRK, with lengths in agreement to voltage level and dimensions in accordance with international standards DIN 43265, IEC and NMX-J-149-1, as described in Figures and Tables of the Selection Guide of Section I, and they are used in combination with load-break fused disconnector switches and fuse-holders. The most common use is for transformers, motors, capacitors, potential transformers, overhead lines and feeder cable protection in substations and for medium and high voltage (2.4 kv up to 38 kv) industrial, rural and urban applications. NOTES: Selection criteria, calculation factors and electrical and mechanical data, are included in this manual, Selection Guides and specifications, are exclusive for high interrupting capacity current-limiting DRIWISA fuses to be used in high voltage systems. Concepts and recommendations described in this manual should be considered and applied according to the specific conditions of every case. When using similar fuses of other brands the corresponding data must be obtained or consulted with the respective manufacturer. H-20

23 SELECTION CHART DRIWISA fuses types DRS, DRK and DRN are manufatured according to the following versions: TYPE END-CODE CHARACTERISTICS / APPLICATION DRS Indoor service, with striker-pin from 2 Amperes. For transformer, motor and overhead lines and cable feeders protection. Commonly used in combination with load-break switches. DRS...F Outdoor service, with striker-pin for polluted or humid environments. The technical information appears as DRS code. Just add the "F" code termination to your order. DRK DRN Indoor service, without striker-pin, with 1/2" thread. For capacitor protection. Indoor service, without striker-pin, 1, 2 and 4 Amperes. Only for potential transformer protection; they have special "e" lengths. For mounting on fuse-holders. General Electrical specifications: MAXIMUM VOLTAGE SERIES (phase to phase) kv DR DR DR DR DR DR DR I-1

24 General mechanical specifications I-2

25 Single Fuses with striker pin for transformer, motor and overhead lines and cable feeders protection. INTERRUPTING MINIMUM RATED CAPACITY INTERRUPTING DIMENSIONS WEIGHT TYPE CURRENT I n I 1 CURRENT I 3 e L 1 2 approx. A ka A mm mm mm mm kg Vmax = 4.8 kv DRS04/125-B DRS04/160-B DRS04/125-B DRS04/160-B DRS04/200-B DRS04/250-B DRS04/315-B Vmax = 7.2 kv DRS07/002-A DRS07/004-A DRS07/006-A DRS07/010-A DRS07/016-A DRS07/025-A DRS07/032-A DRS07/040-A DRS07/050-A DRS07/063-A DRS07/075-A DRS07/100-A Vmax = 7.2 kv DRS07/002-A DRS07/004-A DRS07/006-A DRS07/010-A DRS07/016-A DRS07/025-A DRS07/032-A DRS07/040-A DRS07/050-A DRS07/063-A DRS07/075-A DRS07/100-A DRS07/100-B DRS07/125-B DRS07/160-B DRS07/200-B DRS07/250-B DRS07/315-B DRS07/400-B DRS07/500-B Vmax = 12 kv DRS12/125-B DRS12/160-B DRS12/200-B I-3

26 Single Fuses with striker pin for transformer, motor and overhead lines and cable feeders protection. INTERRUPTING MINIMUM RATED CAPACITY INTERRUPTING DIMENSIONS WEIGHT TYPE CURRENT I n I 1 CURRENT I 3 e L 1 2 approx. A ka A mm mm mm mm kg Vmax = 13.8 kv DRS13/002-A DRS13/004-A DRS13/006-A DRS13/010-A DRS13/016-A DRS13/025-A DRS13/032-A DRS13/040-A DRS13/050-A DRS13/063-A DRS13/075-B DRS13/100-B Vmax = 17.5 kv DRS15/002-A DRS15/004-A DRS15/006-A DRS15/010-A DRS15/016-A DRS15/025-A DRS15/032-A DRS15/040-A DRS15/050-A DRS15/063-A DRS15/075-B DRS15/100-B DRS15/125-B DRS15/160-B DRS15/200-B DRS15/200-B Vmax = 25.8 kv DRS20/002-A DRS20/004-A DRS20/006-A DRS20/010-A DRS20/016-A DRS20/025-A DRS20/032-A DRS20/040-A DRS20/050-A DRS20/063-A DRS20/063-B DRS20/075-B DRS20/100-B DRS20/125-B DRS20/160-B DRS20/125-B DRS20/160-B I-4

27 Single Fuses with striker pin for transformer, motor and overhead lines and cable feeders protection. INTERRUPTING MINIMUM RATED CAPACITY INTERRUPTING DIMENSIONS WEIGHT TYPE CURRENT I n I 1 CURRENT I 3 e L 1 2 approx. A ka A mm mm mm mm kg Vmax = 38 kv DRS30/002-A DRS30/004-A DRS30/006-A DRS30/010-A DRS30/016-A DRS30/025-A DRS30/032-A DRS30/040-A DRS30/050-A DRS30/063-A DRS30/075-B DRS30/100-B Real rated current is determined applying a factor of 90% over the value given in the table, for instance, a 400 A fuse, 400 x 0.9 = 360 A I-5

28 DUAL VERSION. DUAL Fuses with striker pin for transformer, motor and overhead lines and cable feeders protection. INTERRUPTING MINIMUM RATED CAPACITY INTERRUPTING DIMENSIONS WEIGHT TYPE CURRENT I n I 1 CURRENT I 3 e L 1 2 approx. A ka A mm mm mm mm kg Vmax = 4.8 kv Length 1 (192 mm) DRS04/250-B DRS04/315-B Length 2 (292 mm) DRS04/400-B DRS04/500-B DRS04/630-B Vmax = 7.2 kv Length 2 (292 mm) DRS07/125-A DRS07/150-A DRS07/200-A Length 4 (442 mm) DRS07/315-B DRS07/400-B DRS07/500-B DRS07/630-B Vmax = 12 kv Length 2 (292 mm) DRS12/250-B DRS12/315-B DRS12/400-B Vmax = 13.8 kv Length 2 (292 mm) DRS13/125-A DRS13/150-B DRS13/200-B Vmax = 17.5 kv Length 4 (442 mm) DRS15/250-B DRS15/315-B DRS15/400-B Length 5 (537 mm) DRS15/400-B Vmax = 25.8 kv Length 4 (442 mm) DRS20/200-B DRS20/250-B DRS20/315-B Length 5 (537 mm) DRS20/250-B DRS20/315-B Vmax = 38 kv Length 5 (537 mm) DRS30/125-A DRS30/150-B DRS30/200-B I-6