Voltage Definition

Nominal Voltage: voltage between phases for which the system is designated.
Operating Voltage: electrical potentiel difference between 2 conductors in normal conditions.

The cable voltage (Uo/U) is designed by 2 values:
- Uo is voltage between phase and neutral
- U is voltage between phases

For alternative current system having a nominal voltage between 100 V and 1000 V

Operating Nominal Voltage
Cable Voltage
50 Hz
60 Hz
230/400 V (+ or - 10%) 
277/480 V 
300/500 V 
400/630 V (+ or - 10%) 
480 V 
450/750 V 
1000 V 
600 V 
0.6/1 kV 

For alternative current system having a nominal voltage above 1 kV and less than 35 kV (3 phases)

50 Hz
Cable Voltage
Highest voltage of equipment
Operating Nominal Voltage
3.6 kV 
3 kV or 3.3 kV 
1.8/3 (3.6) kV 
7.2 kV 
6 kV or 6.6 kV 
3.6/6 (7.2) kV 
12 kV 
10 kV or 11 kV 
6/10 (12) kV 
17.5 kV 
15 kV 
8.7/15 (17.5) kV 
24 kV 
20 kV or 22 kV 
12/20 (24) kV 
36 kV 
33 kV 
18/30 (36) kV 
60 Hz
Cable Voltage
Highest voltage of equipment
Operating Nominal Voltage
4.4 kV 
4.16 kV 
3.6/6 (7.2) kV 
14.5 kV 
13.8 kV 
8.7/15 (17.5) kV 
26.4 kV 
24.94 kV 
18/30 (36) kV