MV SWITCHGEAR 5 MV current limiting fuses With thermally operated striker From 3. to 3 kv
In line with our customers and their needs. In a sector like energy, which requires the maximum collaboration between all of its components, joining forces clearly aimed at achieving optimum service for final customers and recipients... We are on line Guidelines for which MESA has established protocols which mean that the contribution, help, relations and comprehension of requirements and needs are established within a structured collaboration program subject to a process of continuous improvement. A member of Schneider Electric, MESA was founded in 97. It currently has more than 370 employees, two production plants making up over 0,000 m, and its own power and test laboratories. Its management and production processes are structured in line with ISO 900-000 and ISO 00, and developments are supported by certificates and approvals issued by local and international laboratories and bodies. Only in this way is it possible to provide innovative solutions in medium and high voltage in more than 90 countries. As a result of constantly developing rules and designs, the characteristics of the equipment described in this catalogue may change without prior notice. We can only commit to the availability of this equipment and its characteristics once confirmed by our Technical and Sales Department.
Índice General overview Field of application Main characteristics 5 Construction MV fuses, thermally operated striker 7 CF fuses Dimensions and characteristics References, characteristics and curves 9 Time current and limitation curves 0 MV current limiting fuses With thermally operated striker From 3, to 3 kv Solefuse fuses References and characteristics Time current and limitation curves CF and Tepefuse fuses Measurement transformer protection 3 References, characteristics and curves 3 MGK fuses References, characteristics and curves Selection and user s guide General 5 Transformers protection 5 Motor protection 7 Notes Capacitor bank protection 9 Note about fuses replacement 9 3
General overview Field of application Fuse range selection Our CF, Solefuse, Tepefuse and MGK fuses make up a broad, consistent and uniform range of high breaking capacity fuses and current limiters. They are all of back-up type and they are constructed so that they can be installed in outdoor conditions, as well as indoor, in SF compact switchgear. Their main function is to protect medium voltage distribution devices (from 3 to 3 kv) from both the dynamic and thermal effects of short circuit currents greater than the minimum breaking current of the fuse. Considering their low cost and their lack of required maintenance, medium voltage fuses are an excellent solution to protect various types of distribution devices: Medium voltage equipments (transformers, motors, capacitors, etc.); Public and industrial electrical distribution networks. They offer reliable protection against major faults occuring either on medium or low voltage circuits. This protection can be further enhanced by combining the fuses with low voltage protection systems or an overcurrent relay. Selection table Depending on the equipment to be protected and its voltage rating, the table below gives the range of fuses according to the protection application. Voltage Motors Power Capacitors Voltage (kv) transformers transformers 3, CF CF CF CF MGK 7, CF CF CF CF MGK Solefuse Solefuse CF CF CF CF Solefuse Solefuse Tepefuse 7,5 CF CF CF Solefuse Solefuse Tepefuse CF CF CF Solefuse Solefuse Tepefuse 3 CF CF CF Solefuse Solefuse Tepefuse 3 CF: DIN standard. Transformer, motor and capacitor protection. Solefuse: UTE standard. Transformer and capacitor protection. 3 Tepefuse: UTE standard. Measurement transformers. MGK: UTE standard. Motor protection.
Main characteristics General overview Key characteristics The most significant features provided by our range of fuses are as follows: High breaking capacity. High limitation effects. Thermal protection. Low breaking overvoltage. Low values of I t. Low values of minimum breaking current I 3. With thermally operated striker. For indoor and outdoor (depending on cases). No maintenance. Standards Our fuses are designed and manufactured according to the following standards: IEC-0-, IEC-077 (CF Fuses, Solefuse, Tepefuse, MGK) DIN 35 (CF Fuses) VDE 070-0 (CF Fuses) UTE C00, C0 (Solefuse, Tepefuse) Quality assurance system MESA, the only SCHNEIDER company that manufactures fuses, is certified by AENOR (the Spanish Standards Association), and is certified to ISO 900 and ISO 00 (IQ-NET). MESA performs anually internal breaking capacity tests to guarantee and comply with our quality assurance plan, which, under request, is available for our customers. Watertightness test In order to test the sealing of our fuses, they are plunged into a hot water bath (0 C) for 5 minutes, according to standard IEC 0-. In addition to being tested in our own laboratories, as well as in official laboratories such as the CESI, LABEIN and LES RENARDIERS. Testing During manufacture, each fuse is subject to routine testing with the aim of checking its quality and conformity: Electrical resistance measurement: a key point to ensure that the fuses have the required performance levels at the end of the production process and to check that no damage has occured during assembly. Dimensional and weight control. Visual control of markings. Labelling and external appearance control. Measurement of the resistance of each fuse is therefore carried out in order to check that they are in line with values according to their rated voltage and rated current. () In order to break a current, it is not enough that the fuse melts. For current values less than I 3, the fuse will blow, but may not break. () It is necessary to ensure that the network short circuit is at least equal to the I current of the fuse that is used. Definition of the operating zones of a fuse type accompaniment (back-up) Operating zones of the fuses. I I I 3 I n O Fig. Protection area U N Rated voltage This is the highest voltage between phases (expressed in kv) for the network on which the fuse might be installed. In the medium voltage range, the preferred rated voltages have been set at: 3. - 7. - - 7.5 - and 3 kv. I N Rated current This is the current value that the fuse can withstand on a constant basis without abnormal temperature rise (generally 5 K for the contacts). I 3 Minimum rated breaking current () This is the minimum current value which causes the fuse to blow and break the current. For our fuses, these values are of between 3 and 5 times the I N value. Arcing continues until an external event interrupts the current. It is therefore essential to avoid using a fuse in the range between In and I 3. I Critical currents (currents giving similar conditions to the maximum arc energy) The value of I varies between 0 and 00 times the I Nvalue, depending on then design of the fuse element. If the fuse can break this current, it can also break currents between I 3 and I. I Maximum rated breaking current () This is presumed fault current that the fuse can break. This is the maximum withstand value, specified in table nº5. 5
General overview Construction Cross sectional diagram of a fuse 5 3 3 5 Fig. force (N) 0 70 0 50 0 30 0 0 0 0 5 0 5 0 3 travel (mm) Fig. 3 This graph shows the value of the force provided by the striker according to its length of travel. End contact caps Together with the enclosure, they form an assembly which must remain intact before, during and after breaking the current. This is why they have to withstand mechanical stresses and sealing stresses due to overpressure caused by arcing. They also have to provide the stability of the internal components over time. Enclosure This part of the fuse must withstand certain specific stresses (related to what has already been mentioned): Thermal stresses: the enclosure has to withstand the rapid temperature rise that occurs when the arc is extinguished Electrical stresses: the enclosure has to withstand after breaking. Mechanical stresses: the enclosure has to withstand the pressure caused by expansion of the sand when breaking occurs. 3 Core This is a cylinder surrounded by ceramic fins onto which the fuse element is wound. The striker control wire together with the latter are lodged within the cylinder. They are insulated from the fuse elements. Fuse element This is the main component of the fuse. Materials with low resistivity and which do not suffer wear over time are used. Our fuses have fuse elements with a carefully chosen configuration, defined after a lot of testing. This allows us to achieve the required results. 5 Extinction powder The extinction powder is made up of high purity quarzite sand (over 99.7%), which is free from any metal components and moisture. When it vitrifies, the sand aborbs the energy produced by the arc and forms an insulating component called fulgurite with the fuse element. Thermal striker This is a mechanical device which indicates the correct functioning of the fuse. It also provides the energy required to actuate a combined breaking device. The striker is controlled by a heavy duty wire which, once the fuse element has actuated, also melts and releases the striker. It is important that the control wire does not cause the premature tripping of the striker, causing interference with the breaking process. MESA limiting fuses fitted with a thermal striker are not only able to trip and break against short-circuits (normal functioning), but also able to do it for extended overcurrents which produce important overheatings in the enclosure where the fuse is installed (SF switchgear) and in the components of the fuses themselves. The strikers used on our fuses are of medium type and their force/travel characteristics (approximately joule according to standard IEC-0-) are illustrated in figure 3.
MV fuses, thermally operated striker General overview All MESA fuses include thermal protection system. This system does not provide the fuse the power to break fault currents below the minimum breaking current of the fuse I 3 and above the maximum breaking current (I n ), but activates the conventional striker in the presence of such over-currents. Thus, such overcurrents are detected by means of the thermal striker, either, either visually or combined with appropriate interrupting devices, avoiding incidents from overheating in the installations. This way, the fuse not only operates as a current limiter, but also as a temperature limiter when the fuse is combined with an external breaking device These type of fuses with thermal Striker are perfectly compatible with Back Up standard fuses. Technical / economic advantages / safety The inclusion of the thermal striker in our fuses will bring the following advantages: Protect the fuses and their enclosures from undesirable overheating in installations combined with switch disconnectors or with the possibility of automatic breaking. Respond to unexpected working conditions, frequent or long duration overcharges, as well as human faults coming from wrong selection of the rating or protects in installations with limited ventilation conditions. Signalling and tripping of overloads generated by fault currents located below the minimum breaking current (I 3 ) of the fuse installed and which provoques dangerous operation temperatures, also the soon ageing of the electric equipment insulation to protect. Reduction of the costs caused by destruction of switchgear or costs coming from quality service degradation (repairing times, staff, etc ). The thermal striker is an extra security device, which clearly reduce the risk of danger and accidents in installations, thus increasing the quality of service in the electric power supply. CF fuses installed in a CAS 3 switchgear Thermal protection I I I 3 Operating zone of the thermal striker I n O Fig... 7
CF fuses Dimensions and characteristics Dimensions (mm) Ø5 Fig. 33 L (*) (*) The table nº gives the diameter and length of the fuse according to its rating. For other dimensions apart of the ones specified in table nº, contact our sales department. CAS type RMU with CF fuses installed 33 Ø (*) percutor Ø 3 CF Fuses This is MESA s DIN standard fuse range. When designing this range, particular attention was paid to minimise power dissipation values. It is increasingly common to use RMU units with SF gas as insulating material. In view of these operating conditions, in which the fuse is inserted inside a hermetically sealed fuse chamber virtually without any ventilation, these fuses avoid the premature ageing, both of themselves and of the whole device, which would be caused by a non-optimised fuse. The envelope tube in the CF fuses range up to 00 A (rated current) is made from brown glazed porcelain, which withstands ultra violet radiation and can therefore be installed both outdoors as well as indoors. Fuses with rated current values greater than 00 A are provided with glass fibre tubes and are only for indoor installations. You will find the full list of the CF fuse range in the table nº with rated voltages from 3 to 3 kv and rated currents of up to 50 A, customers can meet their exact requirements in terms of switchgear short circuit protection. Time/current characteristic curves This curve shows the virtual time of melting or pre-arcing time in function of the symmetrical component value of the previewed current. A careful selection of the elements of MESA fuses and in particular, the melting elements as well as a strict manufacturing control, assure MESA s customers the accuracy of the time/current curves, located always under the recommendations and limits of the standard IEC 0-. During the design of our CF fuses, we focused on a relatively high melting current at 0. s in order to withstand transformer s currents and at the same time, a low melting current at 0 s in order to achieve quick breaking in the case of a fault. Please see page nº 0 for the time/current characteristics of CF fuses. Current limitation curves MESA fuses are strong current limiting type. Therefore, large short-circuits are limited before reaching their maximum value. These diagrams show the relation between prospective short circuit current and the maximum value of the cut-off current by the fuse. The intersection between those lines with the one straight lines I max-symmetrical or I mx-asymmetrical indicates the presumed short-circuit current, below which the fuses have not limiting capacity. For example, as shown in the limitation curves on page 0, for a short circuit whose prospective short-circuit current is 5 ka in an unprotected installation, the maximum peak current value would be 7 ka for symmetrical flow and 3 ka for an asymmetrical case. If we had used a CF fuse with a rated current of A, the maximum value reached would have been.5 ka.
References and characteristics CF fuses Reference Rated Operating Rated Max. breaking Min. breaking Breaking cold Power Lenght Diameter Weight voltage (kv) rated (kv) current (A) current I (ka) Current I 3 (A) resistance (*) (mω) dissipation (W) (L) (mm) Ø (mm) (kg) CF-3,/50 (**) 3, 3/3, 50 50.000 0, 5 9 3, CF-7,/ 0 7 0 CF-7,/,3,3 3 05 CF-7,/0 0 3 0 CF-7,/ 50,5 50,5 CF-7,/0 0 53,5 3 CF-7,/5 5 9 3, 35 CF-7,/3,5 CF-7,/0 7, 3/7, 3,5 0 3 0 35 9,3 CF-7,/50 50 0,7 CF-7,/3 CF-7,/0 3 0 5 0,, 5 7, CF-7,/00 00 30 5,5 5 CF-7,/5 (**) 5 50 3, CF-7,/0 (**) 0.000, 7 9 3, CF-7,/00 (**) 00 50.00, 95 CF-7,/50 (**) 50.00 0,9 95 5 CF-/ 0.3 7 CF-/,3,3 3 39 CF-/0 0 3 5, CF-/ 50 0 37 50,5 CF-/0 0 CF-/5 5 9 5 5 CF-/3,5 CF-/0 / 3,5 0 3 0 35 0 59 7 9, CF-/50 50 0 7, 70 CF-/3 3 5 3, CF-/0 0 0 0 0 7 3, CF-/00 00 30 0 (**) CF-/5 5 50 5,3 3 CF-/0 (**) 0 0.000 3,5 7 5 CF-/00 (**) 00.00,7 7 CFR-7,5/0 0 3 03 3 CFR-7,5/ 50 3 7 50,5, CFR-7,5/5 5 9 7 7 9 CFR-7,5/3,5 CFR-7,5/0 3,5 0 0 35 5 35 7 90 7 3, CF-7,5/ 0.3 3 CF-7,5/,3,3 0 3 0 CF-7,5/0 0 3 03 5,5 CF-7,5/ 7,5 0/7,5 50 3 CF-7,5/0 0 03 5 50,5 CF-7,5/5 5 9 7 CF-7,5/3,5 CF-7,5/0 3,5 0 0 35 5 35 7 9 37, CF-7,5/50 50 0 93 CF-7,5/3 CF-7,5/0 3 0 3,5 5 330 9, 3,5 5 7 3,9 CF-7,5/00 00 50 9, CFRR-/,3,3 3 CFRR-/0 CFRR-/ 0 0 0 5 35 50,5, CFRR-/0 0 73 3 CFRR-/5 CFRR-/3,5 5 3,5 3,5 00 79 90 9 7 3, CFRR-/0 0 5 0 CFRR-/50 50 33 30 57 5 CFRR-/3 3 7 3 77 CFR-/0 0 3 5 50,5,5 CFR-/ CFR-/0 0 50 5 3 5 7 37 55, CFR-/5 5 9 5 7 CFR-/3,5 3,5 0 93 7 3,9 CFR-/0 0/ 0 35 5 CF-/ 0 0.3 3 CF-/,3,3 3 5 5 CF-/0 CF-/ 0 3 50 5 3 5 50,5,7 CF-/0 0 3 7 CF-/5 5 9 5 79 CF-/3,5 CF-/0 3,5 0 0 35 9 9 55, CF-/50 50 0 3,5 3 CF-/3 3 3,5 5, 7,5 CF-/0 0 330 00 CF-/00 00 50 3,5 0 5,7 CF-3/ 0.09 5 CF-3/,3,3 3 750 39 CF-3/0 0 3 30 50 50,5,9 CF-3/ 50 5 9 CF-3/0 0 97 0 CF-3/5 3 0/3 5 0 9 33 33 537 55 3, CF-3/3,5 CF-3/0 3,5 0 0 35 03 70 7 07 7 5, CF-3/50 CF-3/3 50 3 00 50 7 35 9 0,5 Table nº (*) Resistances are given at ±0% for a temperature of 0 C. (**) Fuses of rated current > 00 A are provided with glass fiber tube for indoor use. Note: For fuses without thermal striker, please contact our sales department. 9
CF fuses Time current and limitation curves Time-current characteristic curves 3. - 7. - - 7.5 - - 3 kv Time (s) 000 A.3 A 0 A A 0 A 5 A 3.5 A 0 A 50 A 3 A 0 A 00 A 5 A 0 A 00 A 50 A 00 0 0. 0.0 0 00 000 0000 Current (A) Current limitation curves 3. - 7. - - 7.5 - - 3 kv The diagram shows the maximum limited broken current value as a function of the rms current value which could have occured in the absence of a fuse. Maximum peak value of limited cut-off current (ka peak) 00 0 Ia=. Ik Is= Ik 50 A 00 A 0 A 5 A 00 A 0 A 3 A 50 A 0 A 3.5 A 5 A 0 A A 0 A.3 A A 0. 0. 0 00 Prospective short-circuit current (effective ka) 0
References and characteristics Solefuse fuses Solefuse fuses The Solefuse range of fuses is manufactured according to standard UTE C00. Their rated voltage varies from 7. to 3 kv. they can be supplied with or without a striker and their weight is of around kg. They are mainly intended to protect power transformers and distribution networks, and are solely intended for indoor installations (glass fibre enclosure). Dimensions (mm) Ø55 35 50 50 striker 3 max Ø Electrical characteristics Fig. 5 Reference Rated Operating Rated Min. breaking Max. breaking Cold voltage voltage current current current resistance (*) (kv) (kv) (A) I 3 (A) I (ka) (mω) 7573 BC.3 3.5 5. 7573 BE 0 5.7 7573 BH 7. 3/7. 3.5 57.5 50.5 7573 BK 3 35.3 7573 BN 5 5. 7573 CM 7./ 3/ 00 500 50 7.7 7573 DL 7./7.5 3/7.5 0 00 0 5. 7573 EC.3 3.5 5.9 7573 EE 0 93. 7573 EH / 0/ 3.5 57.5 30 5.77 7573 EJ 3 5 3.5 7573 EK 3 35.9 75733 EC (**).3 3.5 7.3 75733 EE (**) 0 7. 75733 EH (**) / 0/ 3.5 57.5 30 7.9 75733 EJ (**) 3 5 39 75733 EK (**) 3 35 9.3 7573 FC.3 3.5.9 7573 FD 0 50 5.9 7573 FE 3 30/3 0 0 07. 7573 FF 0 00 33. 7573 FG 5 5 7573 FH 3.5 57.5 93 Table nº (*) Resistances are given at ±0% for a temperature of 0 C. (**) Fuses with a reference number starting by 7573 have a striker, those that start by 75733 do not.
Solefuse fuses Time current and limitation curves Time-current characteristic curves 7. - - 7.5 - - 3 kv Time (s) 000.3 A 0 A A 0 5 A 3.5 A 3 A 3 A 0 A 00 A 5 A 00 0 0. 0.0 0 00 000 0000 Current (A) Current limitation curves 7. - - 7.5 - - 3 kv The diagram shows the maximum limited broken current value as a function of the rms current value which could have occured in the absence of a fuse. Maximum value of the limited cut-off current (ka peak) 00 0 Ia=. Ik Is= Ik 5 A 00 0 A 3 A 3 A 3.5 A 5 A 0 A 0 A.3 A 0. 0. 0 00 Prospective short-circuit current (effective ka)
Measurement transformer protection References, characteristics and curves CF and Tepefuse fuses MESA manufactures special fuses type Tepefuse and CF designed to protect measurement transformers. Tepefuse fuses are made only in glass fiber for indoor service. Fuses for measurement transformer protection are manufactured without strikers, according to figures and 7. Electrical characteristics TYPE Reference Rated Operating Rated Max. breaking Min. breaking Cold Length Diameter Weight voltage voltage current current current resistence (*) L (*) Ø (*) (kv) (kv) (A) I (ka) I 3 (A) (mω) (mm) (mm) (Kg) Tepefuse 75 A <. 0.3 0 0 75 B 3./. 30 7.5 0. CF CF-7. /.5 7. 3/7..5,7 9 0,9 CF- / 3 3,3 / CF- /.5.5,97 9. CF-7.5 /.5 7.5 0/7.5.5 9.5,07 37 50.5.5 CF- / 0,5 0/ CF /.5.5,07. CF-3 /.5 3 0/3.5 0 3,537 537. Table nº3 (**) Resistances are given at ±0% for a temperature of 0 C. Time-current characteristic curves 7. - - - 3 kv 000 00 Time (s) A (CF) 0.3 A (TEPEFUSE).5 A (CF) Dimensions (mm) CF Ø 5 Ø 50.5 33 L Fig. Tepefuse 33 0 Ø7.5 5 Fig. 7 30 0. 0.0 0 00 Current (A) 3
MGK fuses References, characteristics and curves Dimensions (mm) Ø strike MGK Fuses MGK fuses are intended to protect medium voltage motors at 7. kv (indoor service). Electrical characteristics Reference Rated Operating Rated Min. breaking Max. breaking Cold voltage voltage current current current resistance (*) (kv) (kv) (A) I 3 (A) I (ka) (mω) 7573 00 30 50. 55 75735 5 570 50. 3 7573 7. 7. 0 900 50. 75737 00,00 50.53 Fig. 7573 50,00 50 0.95 Weight:. kg Table nº (*) Resistances are given at ±0% for a temperature of 0 C. Time-current characteristic curve 7, kv 000 Time (s) 00 A 5 A 0 A 00 A 50 A 00 0 0. 0.0 0 00 000 0000 Current (A) Current-limitation curve 7. kv The diagram shows the maximum limited broken current value as a function of the rms current value which could have occured in the absence of a fuse. 00 0 Maximum value of limited cut-off current (ka peak) Ia=. Ik Is= Ik 50 A 00 A 0 A 5 A 00 A 0. 0. 0 00 Prospective short-circuit current (effective ka)
General Selection and user s guide According to their specific characteristics, the various types of fuses (CF, Solefuse, Tepefuse and MGK) provide real protection for a wide variety of medium and high voltage equipment (transformers, motors, capacitors). It is of the utmost importance to always remember the following points: U N of a fuse must be greater than or equal to the network voltage. I of a fuse must be greater than or equal to the network short circuit current. The characteristics of the equipment to be protected must always be taken into consideration. Fuse Transformer Transformers protection I cc Short circuit current A transformer imposes three main stresses on a fuse. This is why then fuses must be capable of: Withstanding the peak start up current associated to transformer connection. The fuse s melting current at 0. s must be higher than times the transformer rated current. I f (0, s) > x I n transfo. Breaking fault currents across the terminals of the transformer secondary. A fuse intended to protect a transformer has to break the circuit in order to prevent the transformer rated short circuit level(i cc ) from damaging the latter. I sc > I f ( s) Withstanding the continuous operating current together with possible overloads To achieve this, the fuse rated current must be more than. times the transformer rated current. I n fuse >, I n transfo. Selection of rating In order to select correctly the fuse rated currents to protect a transformer, the following characteristics shall be taking into account: The transformer characteristics. - Power (P in kva). - Short circuit voltage (U sc in %). - Rated current. The fuse characteristics. - Time/current characteristics (I f 0. s and I f s). - Minimum breaking current (I 3 ). The installation and operating conditions. - Open air, cubicle or fuse chamber. - Presence of permanent overloads. - Short-circuit current at the instalation place. - Indoor or outdoor service. To select MESA fuses, which are installed in SM, RM, CAS or into a Switchboard of other manufacturer, please, refer to the own selection table and recommendations of the switchboard manufacturer. Fig. 9 I 3 I n The customer is required to inform key datas when ordering, to avoid any misunderstandings. As per the following: Rated voltage Operating voltage Rated current Transformer power (or motor power) Operating conditions (open air, fuse chamber ) Fuse length Cap diameter Closing In this current zone, any overloads must be eliminated by LV protection devices or by an MV switch equipped with an overcurrent relay (see pag. 7). Information to provide on ordering I I n kv kv A kva mm mm Standards For orders, please note the reference and characteristics of the fuses. Table nº 5 5
Selection and user s guide Transformers protection Selection tables CF fuses/din standard for transformer protection (rating in A) () () (3) Service Rated Transformer rated power voltage voltage (kva) (kv) (kv) 5 50 75 00 5 0 00 50 35 00 500 30 00 000 50 00 000 5 3.5 0 50 3 3 0 3 7. 0 3.5 0 50 3 0 0 00 00 5 5 0 00 50 5 0 50 3 0 00 00 5 0 0 5 3.5 3.5 0 50 3 3 0 5 7. 0 0 3.5 0 0 50 3 0 0 00 00 5 5 0 00 50 5 0 50 50 3 0 00 00 5 0 0.3 0 5 3.5 0 0 50 3 3 0 7. 0 0 5 3.5 0 50 50 3 0 0 00 00 5 5 0 00 50 5 3.5 0 50 3 3 0 00 00 5.3 0 5 5 3.5 0 50 50 3 0. 7. 0 0 5 3.5 3.5 0 50 3 3 0 00 00 5 5 0 00 50 5 3.5 0 0 50 3 0 0 00 5 0 5 3.5 3.5 0 50 3 3 0.3 0 0 5 3.5 0 0 50 3 0 0 0 00 5 5 0 0 5 3.5 0 50 50 3 0 00 00 00 5 0 0 5 5 3.5 0 50 50 3.3 0 0 5 3.5 3.5 0 50 3 3 0 0 00 5 5 0 0 5 3.5 0 0 50 3 0 0 00 00 5.3 0 0 5 5 3.5 0 50 50 3 3. 7.5 0 0 0 5 3.5 3.5 0 50 3 3 0 0 00 5 5 3.5 0 0 50 3 0 0 00 00.3 0 0 0 5 5 3.5 0 50 50 3 3. 7.5 0 0 5 3.5 3.5 0 50 3 3 0 0 00 00 0 5 3.5 0 0 50 3 0 0 00 00 0 5 3.5 0 0 50 3 3 0 5 7.5.3 0 0 0 5 3.5 0 50 50 3 0 0 00 00 00 0 0 5 5 3.5 0 50 3 3 0 00.3 0 0 5 3.5 3.5 0 50 3 0.3 0 0 0 0 5 3.5 0 0 50 3 3 0 0 00 0 5 5 3.5 0 50 50 3 0 00 00 0 0 0 5 5 3.5 0 0 50 3.3.3 0 0 5 3.5 3.5 0 50 50 3 0 0 00 0 0 5 3.5 0 0 50 3 3 0 00 00.3 0 5 3.5 0 0 50 5 3.3 0 0 0 0 5 3.5 0 50 50 3 3 3 0 5 5 3.5 0 50 3 3.3 0 5 3.5 3.5 0 50 30 3.3.3 0 0 0 0 5 3.5 0 0 50 3 3 3 0 0 5 5 3.5 0 50 50 3 Table nº Solefuse fuses/ute standard for transformer protection (rating in A) () () (3) Service Rated Transformer rated power voltage voltage (kva) (kv) (kv) 5 50 00 5 0 00 50 35 00 500 30 00 000 50 00 3 7. 3.5 3 3 3 0 00 00 5 3.3 7. 3.5 3.5 3 3 0 0 00 5. 7..3 3.5 3.5 3.5 3 3 0 0 00 5 5.5 7..3 3.5 3.5 3.5 3 3 3 0 00 5 7..3 3.5 3.5 3.5 3 3 3 0 00 00 5. 7..3 3.5 3.5 3.5 3 3 0 0 00 5 0.3.3 3.5 3.5 3.5 3 3 3 0 0 00.3.3 3.5 3.5 3.5 3 3 3 0 00 3. 7.5/.3.3 3.5 3.5 3.5 3 3 3 0 5 7.5/.3.3 3.5 3.5 3.5 3 3 3 0 0 0.3.3.3.3 3.5 3.5 3 3 3 3.3.3.3.3 3.5 3.5 3.5 3 3 3 30 3.3.3.3 3.5 3.5 3.5 Table nº7 () Fuse ratings correspond to open air installation with a 30% transformer overload, or to an indoor installation without transformer overload. () If the fuses are incorporated in a distribution switchboard of another manufacturer, please refer to the selection table provided by the manufacturer of this device. (3) Although the ratings shown in bold type are the most appropriate, other ratings can also protect transformers in a satisfactory way.
Motor protection Selection and user s guide When combined with a contactor, the fuse provides a particularly effective protection system for an MV motor. The specific stresses that the fuses have to withstand are due to: The motor to be protected. The network on which it is placed. Stresses due to the motor The start up current (I d ). The start up duration (T d ). The number of successive start ups. When the motor is energised, and throughout the start up period, the impedance of a motor is such that is consumes a current Id which is significantly greater than the rated load current I n. Normally this current Id is around times the rated current (I d /I n =). The start up duration T d depends on the type of load that is being driven by the motor. It is of around 0 seconds. We also have to take into account of the possibility of several successive start ups when selecting the fuse rating. Stresses related to the network The rated voltage: the rated voltage for MV motors is at most equal to kv. The limited broken current: networks with MV motors are generally high installed power networks with very high short circuit currents. Rating selection The selected fuse rating depends on 3 parameters: The start up current. The duration. The start up frequency. CF fuse selection for motor protection Max. operating voltage (kv) Start-up current Start-up duration (s) 5 0 0 Number of start-up per hour 3.3,0 50,90 50 50 50,0 50 50 50 50 50 50,030 50 50 50 50 50 50 90 50 50 50 50 50 50 790 00 50 50 50 50 50 70 00 00 00 50 50 50 0 00 00 00 00 00 50. 0 00 00 00 00 00 00 50 0 0 0 00 00 00 0 0 0 0 00 00 00 0 0 0 0 0 0 00 30 0 0 0 0 0 0 0 5 0 0 0 0 0 50 5 5 5 0 0 0 0 5 5 5 5 5 0 30 5 5 5 5 5 5 0 00 5 5 5 5 5 0 00 00 00 00 00 5 70 00 00 00 00 00 00 0 00 00 00 00 00 00 0 00 00 00 00 00 33 0 0 0 00 00 00 0 0 0 0 0 0 00 0 0 0 0 0 0 0 9 3 0 0 0 0 0 3 3 3 3 0 0 3 3 3 3 3 3 0 73 50 3 3 3 3 3 7 50 50 50 3 3 3 50 50 50 50 50 3 57 50 50 50 50 50 50 Table nº (A) 7
Selection and user s guide Motor protection η = rotor s performance U a = motor s rated current I d = start-up current T d = time of start-up Selection curves The 3 charts given below enable the fuse rating to be determined when we know the motor power (P in kw) and its rated voltage (in kv). Chart : This gives the rated current In (A) according to P (kw) and U N (kv). Chart : This gives the start-up current T n (A), and the start up current is obtained. Chart 3: Indicates the appropriate rating according to I d (A) and the start-up duration time T d (s). Comments Chart is plotted for a power factor (cos j) of 0.9 and an efficiency of 0.9. For values different to this, use the following equation: P I n = h 3Ua cosϕ Chart 3 is given in the case of start-ups spread over an hour or successive startups. n - For n spread start-ups (n > ) multiply T d by. - For p successive start-ups (p > ), multiply Td by p (see selection table). - In the absence of any information, take T d = 0 s. If the motor start up is not direct, the rating obtained using the charts below may be less than the full load current of the motor. In this case we have to choose a rating of 0% over the value of this current to take account of the cubicle installation. The rating of the selected fuses according to the graphs enclosed, comply with the ageing test according to the standard IEC 00. Example A 50 kw motor powered at. kv (point A, chart ) has a current of 7 A (point B). 00 0 00 000 I d (A) 0000 00 The start-up current, times greater than the rated current = 000 A (point C, chart ). For a start-up time of 0 s, chart 3 shows a rating of 50 A (point D). Td (s) x50a x00a Td (s) 50 kw 50A 00A D 0 0 50A 30A 3A 0A 5A 00 A 000 0000 P (kw) 00A C 0 In (A) 00 kv 0kV.kV kv 5.5kV.kV A 3.3kV 3kV B 7 A x x0 x x x 000 A 0 In (A) 00 000 00 P (kw) 000 0000 0 00 000 I d (A) 0000
Capacitor bank protection Notes Fuses intended to protect capacitor banks have to withstand special stresses: When the bank is energised, the inrush current is very high and can lead to premature ageing or fusing of the fuse element. In service, the presence of harmonics can lead to excessive temperature rise. Rating selection A common rule applied to any switchgear in the presence of capacitor banks is to derate the rated current by 30 to 0% due to the harmonics which cause additional temperature rise. It is recommended to apply a co-efficient of between.7 and.9 to the capacitive current in order to obtain the appropriate fuse rating, i.e..7 or.9 times the rated current of the bank. Note about fuses replacement According to the recommendations of the IEC-0-, (Operation Guide): 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 not melted fuse-links. In addition, this guide inform about other useful & basic recommendations for the correct use of the fuses. It is necessary to take into account, that if the striker of a fuse has not operated, that does not mean that it has not suffered from an over current, as the striker only operates once all the fuse elements have been melt. 9
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