66kV On-load Tap
Changer TYPE–T11

OLTC Type T11 is a 3-phase, single compartment, externally mounted compact on-load tap changer of rating 66KV 300A 17 Position with Linear. T11 works on the principle of high speed transition resistance and is suitable for both star and delta connected transformers. T11 works on Flag Cycle, and is rated for bi-directional power flow, max through Current of 300A and Step Voltage of 1000V.

Advantages

This T11 has a Tap Normalizer feature as optional. The Tap- normalizer brings the OLTC to normal tap as soon as the main power fails through UPS, avoiding sudden high voltage to appear on the secondary when power resumes.
The mounting on the transformer is the familiar flange mounting.
The connections to the terminal board from the transformer are push-on, self-locking, improving productivity and making the task easy at the transformer factory.
The tap changer is protected by a pressure relief device provided on the top of the OLTC. The Design has free oil level which eliminates thecConservator. Instead adequate free space is provided in the tank above oil level. The oil level gauge on the side plate helps to ensure correct filling of oil.

Key Features

The entire tap changer unit with selector switch and a drive mechanism chamber are housed in a sheet metal enclosure.
The switch chamber and the drive mechanism are separated by a metal sheet.
The fixed contacts are mounted on lead embedded phase boards. The moving contact slides on both sides of these fixed contacts and selects the tap.
The selector switch combines the functions of a tap selector and a diverter switch.
The drive mechanism is coupled to this selector switch by a drive shaft and series of gears.
It has an energy storage device that releases the energy to drive the selector switch.