High-voltage high-breaking capacity VV fuse-links

Transcription

1 High- high- VV fuse-links [A] (ka) [mω] [W] [A 2 s] [A 2 s] , A , A A A A A , A A A A A A A 810 2, ,1 57 4A , A A A A A , A / A A A A A A 810 2, A A ,7 6,1 57 4A ,7 17, A , A 46 67, A 60 45, A A , A , A , A A A A A A A A

2 [A] (ka) [mω] [W] [A 2 s] [A 2 s] , A , A A A 80 60, A A A A , A , A A A 60 60, A A A A A /12 80 A A A A , A , A A A A A A A A A A A A A A A A

3 [A] (ka) [mω] [W] [A 2 s] [A 2 s] , A , A A A A A A A A A A 550 9, , A , A A A A A / A A A A A A A , A , A A A A A A A A A A A

4 [A] (ka) [mω] [W] [A 2 s] [A 2 s] , A , A A A A 31, A A A A , A , A A A A A /24 40 A A A A A A , A , A A A A A A A A A A A A

5 [A] (ka) [mω] [W] [A 2 s] [A 2 s] , A , A A A , A , A /36 10 A A A ,5 25 A A A A A** Force / travel striker pin diagram Connection in indoor switchgear, example: striker force 120 N VVT-D striker force 80 N VVC striker force 50 N 616

6 Fuse-link VV Cut-off diagram for VV-Thermo fuse links Cut-off Prospective Time- characteristics for VV-thermo fuse links 617

7 High fuse-links for liquid-immersed transformer protection [A] (ka) [mω] [W] [A 2 s] [A 2 s] ,1 57 4A , A A / A VVT-D , A A A ,1 57 4A , A VVT-D A A , /24 4A , A Time- characteristics 10A A VVT-D A A A , High fuses for protection of transformers [A] (ka) [mω] [W] [A 2 s] [A 2 s] 10/ ,1 57 / 20 4A ,

8 Selection of fuses for transformer protection For HV fuse-link selection, following transformer technical features has to be known: n power P n (kva) n Short-circuit U cc (%) n I nt n Inrush usually between 8-12xI nt n Short-circuit I cc n Overload usually 1.4 I nt n Maximum short-circuit duration. Standard 2 sec for transformers up to 630 kva and 3 sec for higher powers Following HV fuse-link technical features has to be known: n U n (kv) n I n n I/t Characteristics According to the curves n Melting (0.1sec) I f (0.1sec) n Melting at 2s ec or 3sec melting time n Minimum I 3 n Breaking I 1 (ka) General about transformer protection: n Fuse-link U n must be higher then network. n Maximum fuse-link I 1 must be higher then short circuit- Icc. n Inrush should not melt the fuse-link. Melting at 100 msec must be higher than 12 times transformer n Fuse-link has to operate before the expected short-circuit damage the transformer Icc > I f (2 sec) or Icc > I f (3 sec) n Fuse-link must be able to withstand possible short duration overloads. I n FUSE > 1.4 I n TRAFO Selection table for VV - THERMO back-up fuse links Pt (kva) 6/7,2 kv 10/12 kv 15/17.5kV Transformer primary Ip at 6 kv Inrush min max I LV * * 250* * 315* * 1600 * Note: nonstandard tube dimension HV Fuse-link LV Fuse- Link NH gg Transformer primary Ip at 10 kv Inrush HV Fuse-link min max LV Fuse- Link NH gg I LV Transformer primary Ip at 15 kv Inrush HV Fuse-link min max LV Fuse- Link NH gg I LV 619

9 Selection table for VV - THERMO back-up fuse links Pt (kva) 20/24 kv 30/36 kv Transformer primary Ip at 20 kv Inrush HV Fuse-link min max LV Fuse- Link NH gg I LV Transformer primary Ip at 30 kv Inrush HV Fuse-link min max LV Fuse- Link NH gg I LV 1-pole fuse-base INDOOR MOUNTING [kv] A [mm] B [mm] C [mm] D [mm] E [mm] F [mm] e Fuse length 7, , internal fuse base e 620

10 1-pole fuse-base OUTDOOR MOUNTING [kv] A [mm] B [mm] C [mm] D [mm] E [mm] F [mm] e Fuse length 7, , external fuse base e Definitions and terms Back-up fuse-links According to standard IEC Fifth edition ( ), item 3.3.3, Back-up fuse is -limiting fuse capable of, under specified conditions of use and behaviour, all s from the maximum (I 1 ) down to the minimum (I 3 ). Back-up fuse links should not operate below theirs minimum. If the short-circuit of the transformer is lower than the minimum, additional protection must be provided. range s ETI VV Thermo fuse-links must be ope at the. At lower operating s without limitation provided, please contact ETI team. Breaking I 1 This value (sometimes named maximum of indicates, that this is the maximum which can be interrupted by the fuse-link. I 1 should be greater than the maximum expected short circuit at the fuse-link site. Minimum I 3 This value (sometimes named minimum is specified for Back-up fuse-links. Up from this, fuse-link is capable to fault. Power dissipation of a fuse-link P n The power dissipation of a VV Thermo fuse-link is specified at the of the fuse-link. For calculations of protection with VV Thermo fuse-link, it should be noted, that operating is normally below half of the. Time- characteristics I/t characteristics represents the correlation between and time up to the melting of a silver fuse element. For coordination with other protection devices, melting integral must be referred for melting times below 100ms. Current limitation This is most significant advantage of fuse-links compared to mechanical switches. Contacts of that switches need much longer time as fuse-link to interrupt fault s. VV fuse-link interrupt fault within few milliseconds and sinusoidal does not reach its peak value. Switching s Between -limiting process, short circuit must be limited and reduced as soon as possible. This require a switching that exceed the normal system and force the to zero. Permissible value of switching is 2.2 times peak value of the maximum. 621