The Low Voltage Coil


Spiral circular coils are used for low voltage winding of transformers. It consists of a single insulated conductor or a number of individually insulated rectangular conductors wound in parallel as a continuous helix in one or more layers. Suitable transpositions are made in the winding to minimize eddy current and thus equalize current distribution & temperature. The layers are separated by precompressed press board cylinders and axial ducts are provided to give adequate cooling in the winding.





The High Voltage Coil


Crossover coil is used for medium voltages. It consists of a single insulated conductor of round wire or strip wound on a former in a number of layers & several turns per layer. Connecting these coils in series builds up required High Voltage and brings about a high series capacitance. This in turns makes for an ideal distribution of the stationery and impulse voltage without oscillations.


Continuous Disc coil is used for high voltage. It comprises one or multiple insulated rectangular conductors wound continuously into a series of disk over axial precompressed spacers with locked redial spacers between discs to provide cooling ducts the complete winding is made without joints.

 

Tapping & Tapping Switch

Tapping required for voltage variation are generally provided on the HV winding of the transformer. Tapping are arranged to cause as little disturbance to the magnetic symmetries as possible, hence reducing the impedance variation over the tapping range and keeping to a minimum the mechanical stress on the windings during short circuit. The tapping of the winding are located in the middle of the coil or they may be spread along the full length of the coil.

On Load Tap Changers

Type : ABS III 200 12 17 17 0
Voltage Class : 11 KV / 22KV / 33KV
Max. Current : 200 A
Tap Position : 17
Type of Tapping Winding : Linear

OLTC Controls will be suitable for

          a. Local Manual.
          b. Local Electrical.
          c. Remote Electrical.
          d. Parallel operations under group simultaneous scheme of master/follow.
          e. Automatic.

OLTC will be completed in all respect and is designed to bolt directly to a flange on the transformer. It will be cart MS tank Driving Machaniaim selector switch, barrier board, load control cable termination, suitable for 3ø, 415V AC Supply. Hand operation arrangement is read. OLTC will be filted with oil and for oil filtration valves will be provided, OLTC will be complete with contactors for Forward and Reverse, 3ø motor, limit switch glands and protective relay will be supplied for gas surges due to contacts and oil reduction in OLTC.

Remote Tap Changer Control Cubicle (RTCC) With AVR Relay:

        1. RTCC Suitable for : Automatic
        2. Finish : Enamel
        3. Paint Schede : B.G.

    With help of RTCC & AVR Relay, driving of tap changer from +10.5 to-15% is fully automatically on full load condition with 2 to 3 secs in step of 1.25% of the rated voltage, when the voltage falls below the specified under voltage limit. The desired output voltage on LV can be set through AVR. On the base of this voltage, driving of tap changer is done after sending verification of input 11000V, 3ø, and voltage.
The time delay control allows the regulator to respond only to voltage fluctuation lasting for periods greater then the selected time delay. The bandwidth control allows the dead band to be set in terms of upper (Lower volts) and lower (Raise volts) voltage limit. Solid-state lamps (LEDS) indicate voltage outside the present limits and control relay operation.