|
CHARGING
CURRENT
 CAPACITANCE
VALUES
Single Permashield (SPS) Picofarads Per Foot (pf/ft.)
Conductor
Size
(AWG/kcmil) |
5kV |
8kV |
15kV |
25kV |
35kV |
|
Insulation |
Insulation |
Insulation |
Insulation |
Insulation |
| 115
Mil |
115
Mil |
140
Mil |
175
Mil |
220 Mil |
260 Mil |
320 Mil |
345 Mil |
420 Mil |
|
6 |
66 |
66 |
58 |
|
| 4 |
76 |
76 |
67 |
|
| 2 |
89 |
89 |
77 |
66 |
57 |
|
| 1 |
97 |
97 |
84 |
72 |
62 |
55 |
48 |
|
| 1/0 |
105 |
105 |
91 |
77 |
66 |
59 |
52 |
|
|
| 2/0 |
114 |
114 |
99 |
84 |
71 |
63 |
55 |
45 |
40 |
| 3/0 |
125 |
125 |
108 |
91 |
77 |
68 |
59 |
48 |
42 |
| 4/0 |
136 |
136 |
117 |
98 |
83 |
74 |
64 |
51 |
45 |
| 250 |
146 |
146 |
125 |
105 |
89 |
79 |
68 |
55 |
48 |
| 350 |
167 |
167 |
143 |
120 |
101 |
88 |
76 |
61 |
53 |
| 500 |
193 |
193 |
165 |
137 |
115 |
101 |
86 |
69 |
60 |
| 750 |
232 |
232 |
198 |
164 |
137 |
119 |
101 |
81 |
70 |
| 1000 |
262 |
262 |
223 |
184 |
153 |
133 |
113 |
90 |
77 |
| 1250 |
244 |
202 |
202 |
168 |
168 |
146 |
123 |
98 |
84 |
| 1500 |
264 |
218 |
218 |
181 |
181 |
157 |
132 |
105 |
90 |
| 1750 |
283 |
233 |
233 |
193 |
193 |
167 |
140 |
112 |
95 |
| 2000 |
300 |
247 |
247 |
204 |
204 |
176 |
148 |
118 |
100 |
| |
69kV
|
115kV
|
138kV
|
Conductor
Size
(AWG/kcmil) |
| Insulation |
| 650
Mil |
800
Mil |
850
Mil |
| 4/0
|
36
|
|
|
| 250
|
38
|
|
|
| 350
|
42
|
|
|
| 500
|
47
|
41
|
40 |
| 750
|
54 |
47
|
45
|
| 1000
|
59
|
52
|
50
|
| 1250
|
64
|
56
|
53
|
| 1500
|
69 |
59
|
57
|
| 1750
|
73 |
62 |
60 |
| 2000
|
76 |
65 |
63 |
CHARGING
CURRENT — In Shielded Cable
The
magnitude of the charging current in a cable
can be determined by using the formula:
Ic = 2p fCEn x 10-6
where:
Ic = Charging Current - milliamperes
f = Frequency - Hertz
C = Cable capacitance - pf/ft.
En = Voltage to neutral - kilovolts
Example:
For a 1/0 AWG 15kV cable with a 175
mil insulation wall:
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