VOLTAGE TRANSFORMER GROUPS
Group 1: Transformers for applications with 100% of rated primary voltage connected to the primary terminals; either, line-to-line or line-to-ground. These transformers are capable of operating at 125% of rated volts in emergency conditions, but cannot exceed 65% of their thermal burden rating to a limit of 75oC temperature rise. This will result in reduced life expectancy. Continuous operation at 110% of rated voltage is permissible provided that the thermal rating is not exceeded.
| Primary Voltage Rating |
Ratio |
B.I.L.
(kV peak) |
| 120 for 208Y |
1:1 |
10 |
| 240 for 416Y |
2:1 |
10 |
| 300 for 520Y |
2.5:1 |
10 |
Group2: These are for line-to-line connection but may be connected line-to neutral not exceeding the rated line voltage divided by the square root of 3. Continuous operation at 110% of rated voltage is permissible provided that the thermal rating is not exceeded.
| Primary Voltage Rating |
Ratio |
B.I.L.
(kV peak) |
| 120 for 208Y |
1:1 |
10 |
| 240 for 416Y |
2:1 |
10 |
| 300 for 520Y |
2.5:1 |
10 |
| 480 for 480Y |
4:1 |
10 |
| 600 for 600Y |
5:1 |
10 |
BURDEN DATA
| Burden |
VA |
PF |
PF Angle (degrees) |
| W |
12.5 |
0.1 |
84.3 |
| X |
25 |
0.7 |
45.6 |
| M |
35 |
0.2 |
78.5 |
| Y |
75 |
0.85 |
31.8 |
| Z |
200 |
0.85 |
31.8 |
| ZZ |
400 |
0.85 |
31.8 |
|
