CRMagnetics Catalog

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Potential Transformers
Voltage Transformer Groups
122
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Group 1. Transformers for application 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, with a limit of 75°C. temperature rise. This will result in a reduced life expectancy. Consult the factory for details. continuous opera-
tion at 110% of rated voltage is permissible, provided that the thermal burden rated volt - amperage is not exceeded.
Group 2. Transformers are for line-to-line connection, but may be connected line-to-neutral at a voltage of the rated line volts divided by the
square root of three. continuous operation at 110% of rated voltage is permissible, provided that the thermal burden rated volt-
amperes is not exceeded.
Rated Primary Voltage
for Rated System Voltage
Line-to-Line
Turns
Ratio
Basic Impulse Insulation
Level (kV Crest)
840 1455Y* 7:1 10
840 1455Y* 10:1 10
840 1455Y* 20:1 10
840 1455Y* 35:1 10
840 1455Y* 40:1 10
Rated Primary Voltage
for Rated System
Voltage Line-to-Line
Turns
Ratio
Basic Impulse Insulation
Level (kV Crest)
7200 for 12470Y 1:1 10
8400 for 14560Y 1:1 10
12000 for 20785Y 1:1 10
14400 for 24940Y 1:1 10
Rated Primary Voltage
for Rated System
Voltage Line-to-Line
Turns
Ratio
Basic Impulse Insulation
Level (kV Crest)
2400 for 2400Y 20:1 45
3300 for 3300Y* 30:1 60 or 45
4200 for 4200Y* 35:1 60 or 45
4800 for 4800Y 40:1 60 or 45
7200 for 7200Y 60:1 75 or 110
8400 for 8400Y* 70:1 75 or 110
11000 for 11000Y 100:1 95 or 110
Rated Primary Voltage
for Rated System
Voltage Line-to-Line
Turns
Ratio
Basic Impulse Insulation
Level (kV Crest)
12000 for 12000Y 100:1 95 or 110
13200 for 13200Y 110:1 95 or 110
14400 for 14400Y 120:1 95 or 110
18000 for 18000Y* 150:1 125*
21000 for 21000Y* 175:1 125*
24000 for 24000Y 200:1 125 or 150
27600 for 27600Y* 240:1 150 or 200
34500 for 34500Y 300:1 150 or 200
Group 4. Transformers are for line-to-ground connection, indoors only. The neutral terminal is insulated to withstand a test voltage of 10kV.
They may be continuously operated at 110% of rated voltage, provided that the thermal burden rated volt-amperes is not exceeded.
Group 4A transformers are capable of operating at 125% of rated volts in emergency conditions, but cannot exceed 65% of their
thermal burden rating, with a limit of 75°C. temperature rise. This will result in a reduced life expectancy. Consult the factory for
details.
Rated Primary Voltage
for Rated System Voltage
Line-to-Line
Turns
Ratio
Basic Impulse Insulation
Level (kV Crest)
2400 for 4160 GND Y 20:1 65 or 45*
4200 for 7200 GND Y 35:1 75
4800 for 8320 GND Y 40:1 75
7200 for 12470 Y 60:1 110
8400 for 14560 GND Y 70:1 110
Group 4A for Operation at 100% Rated Voltage
Rated Primary Voltage for
Rated System Voltage
Line-to-Line
Turns
Ratio
Basic Impulse Insulation
Level (kV Crest)
4200 for 4160 GND Y 35:1 65 or 45
4800 for 4800 GND Y 40:1 65 or 45
7200 for 7200 GND Y 60:1 75
8400 for 8400 GND Y 70:1 75
11000 for 11000 GND Y 100:1 110
12000 for 12000 GND Y 100:1 110
13200 for 13200 GND Y 110:1 110
14400 for 14400 GND Y 120:1 110
Group 4B for Operation at 58% Rated Voltage
* Not recognized in ANSI/IEEE C57.13
NOTE: Voltage Transformers connected line-to-ground on an ungrounded system cannot be considered to be grounding transformers and must be
operated with the secondaries in closed delta because excessive currents may flow in the delta. For further details see ANSI/IEEE C57.13
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