Description

• L.T. Tape insulated varnish impregnated type Voltage Transformer, 1Ph/3Ph
• L.T/H.T Cast Resin type Voltage Transformer, 1Ph/3Ph upto 33KV
• H.T. Outdoor Oil Cooled type Voltage Transformer upto 66 KV
• H.T. Cast Resin / Oil Filled type Residual Voltage Transformer for Capacitor Bank protection

• The main function of the Voltage Transformer is to reproduce the Primary Voltage on its secondary side. The Voltage Transformer isolates the devices connected to their secondary circuit from the network system. Voltage Transformers are specially designed for measuring and protection applications.

• Rated Primary Voltage: This is the rated voltage required to be stepped down for measurement and protective purposes.
• Rated Secondary Voltage: The voltage at which the meters and protective devices connected to the secondary of the voltage transformer operate.

• This is the ’load’ in terms of volt- amperes (VA) posed by the devices connected in the secondary circuit on the VT.
• Accuracy Class Required: The transformation errors that are permissible, including voltage (ratio) error and phase angle error. Phase error is specified in minutes. Typical accuracy classes are Class 0.2, 0.5, Class 1 and Class 3. Both metering and protection classes of accuracy are specified. In a metering VT, the VT is required to be within the specified errors from 80% to 120% of the rated voltage. In a protection VT, the VT is required to be accurate from 5% upto the rated voltage factor times the rated voltage.

• Depending on the system in which the VT is to be used, the rated voltage factors to be specified are different. The table below is adopted from Indian and International standards.