Nominal Voltage
Voltage of cables and wires, by which the construction and the tests in respect of electrical characteristics are to be referred.
According to DIN VDE 0298 and IEC 183 the cables are specified U0/U, where
U0 = cable nominal voltage between the conductor and the metal covering or earth and
U
= cable nominal voltage between the phase conductors, for 3-phase U = √3 U0
According to IEC regulations, the maximum permissible voltage Um is given in brackets.
The identification is: U0/U (Um)
As the insulation of plastic insulated cables are measured with a nominal voltage U0/U = 0.6/1 kV and all radial field cables for the voltage U0, these cables are suitable for installation:
- in single phase systems, in which the both phase conductors are insulated, with nominal voltage UN = 2 U0
- in single phase systems, in which one phase conductor is grounded, with the nominal voltage UN = U0
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Operating Voltage
Voltage between conductors of a power system or between a conductor and ground under specified condition in a given time during an undisturbed operation.
Coordination of Cable Nominal Voltages
Nominal Voltage
U0/U (kV) |
For 3-phase
System (kV) |
For 1-phase Alternating Current |
Both phase conductors
insulated (kV) |
One phase conductor
grounded (kV) |
0.6/1 |
1 |
1.2 |
0.6 |
3.6/6 |
6 |
7.2 |
3.6 |
6/10 |
10 |
12 |
6 |
12/20 |
20 |
24 |
12 |
18/30 |
30 |
36 |
18 |
Coordination of Maximum Permissible Operating Voltages
Nominal Voltage
U0/U (kV) |
Max. Voltage for
3-phase
System (kV) |
For 1-phase Alternating Current |
Both phase conductors
insulated (kV) |
One phase conductor
grounded (kV) |
0.6/1 |
1.2 |
1.4 |
0.7 |
3.6/6 |
7.2 |
8.3 |
4.1 |
6/10 |
12 |
14 |
7 |
12/20 |
24 |
28 |
14 |
18/30 |
36 |
42 |
21 |
Note:
Cable with U0/U 0,6/1 kV is allowed for Direct Current Systems, of those the maximum operating voltage conductor/conductor 1.8 kV or conductor/ground 1.8 kV not to be exceeded.
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