Background:
The protection and management of MV / LV transformers in a rural environment requires specific Circuit Breakers compatible with significant unbalanced overloads, thus ensuring full exploitation of the installed power, even in unbalanced operations.
Descriptions:
Circuit Breaker Unit
Tetrapolar circuit breaker (three-phases protected + neutral) uses air break technology: arc is divided into different sections by metal barriers.
When the circuit breaker is open, electrical connection is made to put the transformer’s neutral to the earth.
When the circuit breaker is closed, a spark gap limits the rise in potential of the LV neutral from the earth, for a value exceeding 10 kV.
Digital Trip Unit
Digital Trip Unit protects the pole- mounted transformer of 50 kVA, 100 kVA or 160 kVA, and works with conventional transformer (no internal protection) or new transformer with MV fuses (TPC). User has just to set the correct rate from a selector, according to transformer’s power.
Pole Circuit Breaker
|
|
CIRCUIT B
|
REAKERS
|
|
D165T
|
D265T
|
|
Strandard
|
HN 63-S-11
|
HN 63-S-11
|
|
Rated Voltage
|
440 V
|
440 V
|
|
Rated Current
|
165 A
|
265 A
|
|
Rated short-circuit breaking capacity Rated short-circuit making current
|
4 000 A
6 800 A
|
6 400 A
11 700 A
|
|
Number of poles
|
4
|
4
|
|
Number of outputs
|
1 ouput
|
2 outputs
|
|
Cables cross-sections
|
25 / 70 mm2
|
50 / 150 mm2
|
|
Rated power-frequency withstand voltage (50Hz - 1min)
|
4 kV
|
4 kV
|
|
|
|
|
10 kV
|
10 kV
|
|
Rated lightning impulse withstand voltage (1.2/50µs)
|
20 kV
|
20 kV
|
|
Control system
|
Manual
|
Manual
|
|
Installation
|
Middle or Top pole
|
Middle or Top pole
|
Digital Trip Unit
|
|
P = 50 kVA
|
P = 100 kVA
|
Trip time
|
P = 160 kVA
|
Trip time
|
|
U = 440 V
|
U = 440 V
|
U = 440 V
|
|
I = 72,2 A
|
I = 144,3 A
|
I = 231 A
|
|
Current in each phase (in A)
|
Current in each phase (in A)
|
Current in each phase (in A)
|
|
1
|
2
|
3
|
1
|
2
|
3
|
Min
|
Max
|
1
|
2
|
3
|
Min
|
Max
|
|
Temperature = + 20 °C
|
|
Initial load
|
48
|
48
|
48
|
96
|
96
|
96
|
|
|
155
|
155
|
155
|
|
|
|
Three-phases
|
85
|
85
|
85
|
170
|
170
|
170
|
1 h 35
|
1 h 10
|
280
|
280
|
280
|
55 mn
|
1 h 10
|
|
100
|
100
|
100
|
200
|
200
|
200
|
25 mn
|
320
|
320
|
320
|
26 mn
|
|
160
|
160
|
160
|
320
|
320
|
320
|
30 s
|
6 mn
|
500
|
500
|
500
|
30 s
|
7 mn 30 s
|
|
balanced overload
|
950
|
950
|
950
|
1900
|
1900
|
1900
|
0,02 s
|
0,2 s
|
3000
|
3000
|
3000
|
0,02 s
|
0,1 s
|
|
2000
|
2000
|
2000
|
4000
|
4000
|
4000
|
0,02 s
|
0,05 s
|
5640
|
5640
|
5640
|
0,015 s
|
0,025 s
|
|
6400
|
6400
|
6400
|
0,015 s
|
0,020 s
|
|
Three-phases
|
58
|
58
|
120
|
116
|
116
|
240
|
1 h 50
|
50 mn
|
185
|
185
|
400
|
32 mn
|
33 mn
|
|
58
|
58
|
160
|
116
|
116
|
320
|
15 mn
|
185
|
185
|
500
|
11 mn
|
|
unbalanced overload
|
58
|
58
|
220
|
116
|
116
|
440
|
30 s
|
7 mn
|
185
|
185
|
700
|
30 s
|
4 mn
|
|
0
|
0
|
950
|
0
|
0
|
1900
|
0,02 s
|
0,2 s
|
0
|
0
|
3000
|
0,02 s
|
0,1 s
|
|
Temperature = - 25 °C
|
|
Initial load
|
76
|
76
|
76
|
152
|
152
|
152
|
|
|
240
|
240
|
240
|
|
|
|
Three-phases
|
110
|
110
|
110
|
220
|
220
|
220
|
1 h
|
44 mn
|
350
|
350
|
350
|
1 h
|
45 mn
|
|
balanced overload
|
130
|
130
|
130
|
260
|
260
|
260
|
14 mn
|
420
|
420
|
420
|
14 mn
|
|
190
|
190
|
190
|
380
|
380
|
380
|
30 s
|
5 mn
|
600
|
600
|
600
|
30 s
|
5 mn
|
|
Three-phases
|
87
|
87
|
130
|
174
|
174
|
260
|
2 h 15
|
30 mn
|
280
|
280
|
420
|
2 h 15
|
48 mn
|
|
unbalanced overload
|
87
|
87
|
180
|
174
|
174
|
360
|
10 mn
|
280
|
280
|
560
|
13 mn
|
|
87
|
87
|
240
|
174
|
174
|
480
|
30 s
|
6 mn
|
280
|
280
|
760
|
40 s
|
5 mn 40 s
|
|
Temperature = + 50 °C
|
|
Initial load
|
25
|
25
|
25
|
50
|
50
|
50
|
|
|
80
|
80
|
80
|
|
|
|
Three-phases
|
70
|
70
|
70
|
140
|
140
|
140
|
1 h 30
|
1 h 07
|
231
|
231
|
231
|
1 h 05
|
1 h 05
|
|
balanced overload
|
90
|
90
|
90
|
180
|
180
|
180
|
20 mn
|
300
|
300
|
300
|
17 mn
|
|
160
|
160
|
160
|
320
|
320
|
320
|
45 s
|
5 mn
|
500
|
500
|
500
|
35 s
|
5 mn 40 s
|
|
Three-phases
|
48
|
48
|
100
|
96
|
96
|
200
|
1 h
|
1 h
|
155
|
155
|
320
|
1 h
|
1 h
|
|
unbalanced overload
|
48
|
48
|
130
|
96
|
96
|
260
|
15 mn
|
155
|
155
|
420
|
15 mn
|
|
48
|
48
|
200
|
96
|
96
|
400
|
30 s
|
7 mn
|
155
|
155
|
650
|
30 s
|
7 mn
|
