Medium Voltage Distribution

Medium voltage fuses Contents Fuse range selection 2 Fusarc CF, Soléfuse, Tépéfuse, MGK MV limiting fuses with thermal striker Fuse and limitation curves 10 Fuse and limitation curves 12 Metering transformer protection 13 References, characteristics and curves 14 Selection and usage guide General - Transformer protection 15 Transformer protection - Selection table 16 Motor protection - Selection charts 18 ^ Capacitor bank protection 19 Comments on substituting fuses 19

Fuse range selection Public distribution Our Fusarc CF, Soléfuse, Tépéfuse and MGKfuses make up a broad, consistent and uniform range of high breaking capacity fuses and current limitors. They are all of combined type and are manufactured so that they can be installed both indoors and outdoors (depending on the type). Schneider Electric fuses provide protection to medium voltage distribution devices (from 3 to 36 kV) from both the dynamic and thermal effects of short-circuit currents greater than the fuse's minimum breaking current. Considering their low cost and their lack of required maintenance,...

Main characteristics The most significant features provided by our range of fuses are as follows: ■ High breaking capacity ■ High current limitation ■ Dependable breaking of critical currents ■ For indoor and outdoor applications ■ With a thermal striker ■ Low minimum breaking current values. Our fuses are designed and manufactured according to the following standards: Quality assurance system In addition to being tested in our own laboratories as well as in official laboratories such as the CESI, Les Renardiersand Labein, with their own respective certificates, our fuses are manufactured according...

Main characteristics Safe operating Figure 1: definition of a fuse's operating zone. 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: This is the current value that the fuse can withstand on a constant basis without any abnormal temperature rise (generally 65 Kelvin for the contacts). I3: 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 between 3 and 5 times...

Fusarc CR Soléfuse, Tépéfuse, MGK Figure 2: this graph shows the value of the force provided by the striker according to its length of travel. 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. The stability of the internal components must also be ensured overtime. This part of the fuse must withstand certain specific stresses (related to what has already been mentioned): ■ Thermal stresses: the enclosure has...

with thermal striker Fusarc CF fuses installed in a CAS 36 cubicle All Schneider Electric fuses (type Fusarc CF) are provided of a thermal protection device. In the case of permanent overcurrents lower than 13 and superior to the rated current (In), the fuse mechanical striker acts opening the device associated and avoiding any incidents due to overheatings. In this way, the fuse not only works as a current limiter but also as a temperature limiter when combined with an external breaking device. These types of fuses, which integrate a thermal striker, are fully compatible with standard Back UP...

This is Schneider Electric's DIN standard fuse range. When designing this range, we paid particular attention to minimise power dissipation. It is increasingly commonto use RMU units with SF6gasasthe insulating material. In view of these operating conditions, in which the fuse is inserted inside a hermetically sealed fuse chamber, with virtually no ventilation, these fuses avoid premature ageing of themselves and of the whole device which would otherwise be caused by a non-optimised fuse. The enclosure in the Fusarc CF range up to 100 A (rated current) is made from crystallised brown porcelain...

* Resistances are given at ±10% fora temperature of 20°C. Fuses > 100 A rated current, are manufactured in glass fibre (for indoor use).

* Resistances are given at ±10% fora temperature of 20 °C. Fuses > 100 A rated current, are manufactured in glass fibre (for indoor use).

The Soléfuse range of fuses is manufactured according to UTE standard C64200. The rated voltage varies from 7.2 to 36 kV. They can be supplied with or without a striker and their weight is of around 2 kg. They are mainly intended to protect power transformers and distribution networks, and are solely for indoor installations (glass fibre enclosure). Electrical characteristics "Resistances are given at ±10% fora temperature of20°C. ** Without striker.

(metering transformer protection) References, characteristics and curves We manufacture Tépéfuse and Fusarc CF type fuses intended for metering transformer protection which have the following references and characteristics: "Resistances are given at ±10% fora temperature of 20°C. Tépéfuse fuses are only made in glass fibre when intended for indoor usage. Fuses for metering transformer protection are made without strikers, according to figures 6 and 7.

References, characteristics and curves MGK fuses are intended to protect medium voltage motors at 7.2 kV (indoor application). Electrical characteristics "Resistances are given at ±10% fora temperature of 20°C. Current limitation curve 7.2 kV Maximum value of limited broken current (kA peak) The diagram shows the maximum limited broken current value as a function of the rms current value which could have occurred in the absence of a fuse. Rms value of presumed broken current (kA)

Selection and usage guide Transformer protection Short circuit (1) In this current zone, any overloads must be eliminated by LV protection devices or by a MV switch equipped with According to their specific characteristics, the various types of fuses (Fusarc CF, Soléfuse, Tépéfuse 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 rememberthe following points: ■ Un of the fuse must be greater than or equal to the network voltage ■ 11 of a fuse must be greater than or equal to the...