Medium Voltage current limiting Fuse links

Transcription

1 Medium Voltage current limiting Fuse links Type PCEF for indoor and outdoor use Rated Voltage kv Current Rating 6 200A

2 1. General information P&C Medium Voltage fuse-links named PCEF are designed to protect devices in switch-gears and other equipment (distribution transformers, capacitors, motors) from thermal and dynamic effects of short circuits and overcurrents. Time-current characteristics correspond to standard IEC , item , Back-up fuse. They are suitable for installation in Indoor and outdoor switchgear 2. Features The most significant features of P&C Medium voltage fuses are Low temperature rise because of low power dissipation High breaking capacity ka for 12kV and kv for 24kV Reliable sealing system against humidity irruption Low switching voltages 3. Standards P&C Medium Voltage fuse-links comply with the following standards and specifications: IEC , Sixth edition 11/2005 Current limiting fuses Application guide for the selection of high voltage current limiting fuse-links for transformer circuits IEC Specification for high-voltage fuse-links for motor circuit applications IEC High-voltage fuses for external protection of power capacitors 4. Construction P&C Medium voltage fuses are designed to assure stable and reliable characteristics. The glazed porcelain tube (made in ETI/ Slovenia / Europe) is extremely high mechanical and thermal resistant. Galvanically protected contact caps made of electrolytic copper are nickel - or upon customer request silver plated. The design and method of production of the melting elements ensures precisely tolerances and stable time/current characteristics. Fuse elements are wounded on a ceramic carrier (Star-core) and electrically welded on special copper strips. The inside of the tube is filled with quarz sand with an exactly determined granulation and chemical structure. The sand guarantees good and reliable extinguishing of the electric arc. The HRC generation of fuse link type PCEF are designed and tested according to IEC Publication (IEC 282-1). Dimensionally the fuse links are in accordance with DIN 436.

3 P&C fuse links have the following properties: - Low minimum breaking current - Low power losses - Low arc-voltage - High breaking capacity up to ka - High current limitation. Low power losses permit installation of these fuse-links in compact switchgear. PCEF fuses are of back-up type. They have a zone between the minimum melting current and the minimum breaking current where the fuse links may fail to interrupt. For PCEF fuse links this zone is very narrow with a minimum breaking current (I 3 ) of less than 3 & 4 times the rated current. 5. Overvoltages In order to be current limiting, the fuse link must generate an arc-voltage exceeding the instantaneous value of the operating voltage. The over voltage generated by the PCEF fuse link is below the maximum permissible value acc. to IEC The PCEF fuse link can safely be used if the system line voltage is -100% of the rated fuse link voltage. 6. Replacement of melted links The fuse links can't be regenerated according to IEC Publication All three fuse links should be replaced, even if only one or two of the fuse links in the three phase system have operated. Exceptions are allowed when it can be verified that the fuse links have not experienced any overcurrent. 7. Nameplate The symbols on the nameplate have the following meaning: - In Rated current - Un Rated voltage - I 3 Minimum breaking current - I 1 Minimum short circuit current for which the fuse is tested. The arrowhead on the nameplate indicates in which end of the fuse link the indicator and striker appears. Additionally this end contact of the fuse link is specially marked. PCEF-U is outdoor type.

4 P&C Type PCEF I n = 100 A I 3 < 3 x I n U n = 12 kv I 1 = ka High Voltage Current Limiting Fuse-Link According to IEC Made In Egypt 8. Melting times The characteristics are equal for all rated voltages and are recorded from cold condition. In uncertain interruption zone the curves are dotted.

5 9. Current limitation PCEF fuse links are current limiting. A large short circuit current will therefore not reach its full value. The diagram shows the relation between the prospective short circuit current and the peak value of the cutoff current. Substantial current limitation results in a considerable reduction of the thermal and mechanical stress on the high voltage installation. (Prospective current [ka] (rms 10. Indicator and striker pin The PCEF fuse link is equipped with a combined indicator- and striker system, which is activated immediately when the fuse element melts. The force diagram is in accordance with the requirements of IEC (IEC 282-1) and DIN 436.

6 11. Choice of fuse links Choice of rated voltage U N : The rated voltage of the fuse links must be equal to, or higher than the operating line voltage. By choosing the fuse link rated voltage U n considerably higher than the line voltage, the maximum arc voltage must not exceed the insulation level of the network. Choice of rated current I N : To obtain the best possible current limitation, and thereby also protection, I N must be chosen as low as possible compared to the rated current of the object to be protected. However, the following limitations must be taken into consideration: The largest load current must not exceed I N. Cooling conditions (e.g. in compact switchgear). Inrush current of off load transformers. For the choice of rated current of fuse links for protection of transformers, the relation between the power rating of the transformers, operating voltage and rated current of the fuse link is given in the table below. The same table indicates the highest rated current of the low voltage fuse link (on the low voltage side of the transformer) which gives discrimination with the high voltage fuse link. The low voltage fuse link is of the type gl (VDE) or gg/ gm(iec). Technical data (PCEF fuse)

7 12. Dimensions and data PCEF 12kV Type Order code In(a) e(mm) d(mm) I1(KA) Wn(watt) V(Kg) PCEF 12-6 EGTF R12 J PCEF EGTF R12 J PCEF EGTF R12 J PCEF EGTF R12 J PCEF 12- EGTF R12 J0 47 PCEF EGTF R12 J PCEF EGTF R12 J PCEF 12- EGTF R12 J0 70 PCEF EGTF R12 J PCEF 12- EGTF R12 J0 78 PCEF EGTF R12 J PCEF 12-1 EGTF R12 J1 1 1 PCEF EGTF R12 J PCEF EGTF R12 J kV Type Order code In(a) e(mm) d(mm) I1(KA) Wn(watt) V(Kg) PCEF 24-6 EGTF R24 J PCEF EGTF R24 J PCEF EGTF R24 J PCEF EGTF R24 J PCEF 24 - EGTF R24 J0 79 PCEF EGTF R24 J PCEF EGTF R24 J PCEF 24 - EGTF R24 J0 130 PCEF EGTF R24 J PCEF 24 - EGTF R24 J PCEF EGTF R24 J PCEF 24-1 EGTF R24 J

8 (P&C) Head Office: Factory: 266 Omer Ebn El-Katab, Gesr El-Suez Mubarak Industrial City Cairo, Egypt Industrial Zone 2 Tel. / Fax: El-Menoufia Mobile: Egypt protection.control@egpandc.com