24kV PT Cabinet

PT Cabinet: This is inside the 24kV PT cabinet on the other end, right before the air-break switches.

Instrument Transformer

 CT (200kHz, 600-1A)

 CT (200kHz, 800-33A)

 CT (750-1550Hz, 5000-5A)

PT (1.2kHz, 1000-100V)

Ritz Magnetic Voltage Transformer

Protection of Voltage Transformers

Voltage transformers rated for system voltage of up to 34.5 kV are protected by a current-limiting fuse. Above this voltage rating, it is difficult to find a fuse of adequate fault-interrupting rating.

The primary fuse current rating is selected to protect the VT against the bolted fault on the secondary terminals. The VT is designed to withstand the mechanical and thermal stresses resulting from a bolted fault at the secondary terminals for a duration of 1 s.

A miniature circuit breaker or a fuse on the secondary is used to protect the VT against overloads. The secondary protective device must carry the rated current at the thermal burden. The secondary protective device is located near the VT. If a number of loads are fed by the VT, each branch is protected by a molded-case circuit
breaker or a fuse not higher than half the rating of the main protective device.

The primary or secondary fuse elements shall not be mechanically weak, as they can open the circuit due to vibration or if dropped accidentally. The primary fuse on the VT connected to an isolated phase bus in a power plant is subject to vibration. 
A current-limiting fuse rated 0.5 A for a 0.3Z VT may fail under such conditions. Discuss with the manufacturer and increase the fuse rating to 0.75 A or 1.0 A. However, ensure that the large fuse protects the VT against the secondary fault current.

 A fused-protected, control voltage transformer.

General Electric Voltage Transformer

69 KV ALSTOM Power Metering Potential Transformers

High voltage potential transformers

for power metering in electrical power distribution systems.

ALSTOM Power : UXTR-69   (69,000 GY/40,250)

 P.T Ratio: 350/600:1

 

Haefely Trench Coupling Capacitor Voltage Transformers

Haefely Trench Coupling Capacitor Voltage Transformers

• TT&A Inventory Number: 64-1000
• Manufacturer: Haefely Trench AG
• Year of Manufacture: 1996
• Type No.: TEVF 345
• System: 60 Hertz
• BIL: 1,550 KV
• For Nominal: 345 KV
• Maximum Rated Voltage: 209 KV
• Perf. Reference Voltage: 190,200 Volts
• Capacitance Total Nominal: 2,150 pF, C1: 2,284 pF, C2: 87,411 pF
• Thermal Burden Rating: 1,000 VA @ UPF
• Low Voltage Terminals:
  • Y1-Y3, X1-X3, 115 Sec. Volts, 1,732:1 Marked Ratio
    0.6WXYZ Accuracy (ANSI), 200 VA (Nom.)
  • Y2-Y3, X2-X3, 66+ Sec. Volts, 3,000:1 Marked Ratio
    0.6WXYZ Accuracy (ANSI), 200 VA (Nom.)
• Total Weight: 1,000 lbs

Voltage Transformer 110 KV

Voltage Transformers

A fused-protected, control voltage transformer.

Xfmr-Potential Transformers Failed

Haefely-Trench-Capacitor-Voltage-Transformer

Alstom-Outdoor-Voltage-Transformer

ABB-Voltage-Transformer