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ABS III 200/300 Delta-30 is an On Load Tapchanger suitable for application at taps situated anywhere in 33kV windings. It can be supplied either for Single Phase or Three Phase applications. For Three Phase application, the Transformer can be connected either in Star or in Delta. This Tapchanger is available in several standard executions as follows.

i) A 9 Position version suitable for linear tapping arrangement with 8 taps giving nine different voltages.

ii) A 17 Position version suitable for linear tapping arrangement with 16 taps giving 17 different voltages.

iii) A 17 Position version equipped with a Pre Selector, which can be used either as a Reversing Switch, or as a Coarse/Fine Selector. This is suitable for 17 different voltages, with tappings arranged with 8 Fine Taps and an equivalent Coarse section (for coarse/fine arrangement).

iv) A 12 Position version suitable for linear tapping arrangement with 11 taps giving 12 different voltages.

v) The same Tapchanger as above, but equipped with a Pre Selector, which can be used either as a Reversing Switch, or Coarse/Fine Selector. This gives 23 different voltages with tappings arranged with 11 taps in the Fine section and an equivalent Coarse section (for coarse/fine arrangement).

All Tapchangers suit potentiometric tappings with a wander lead.

The current rating is either 200A or 300A depending upon the version selected.

In all these Tapchangers, the function of Tap Selector and Divertor Switch are combined in a Rotary Selector Switch. The Selector Switch employs a double resistance transition arrangement, giving a Flag Cycle of transition according to IS 8468. Thus, these Tapchangers are suitable for Bidirectional Power Flow to the fullest extension of their ratings.

The Selector Switch, and its integrally mounted stored energy Driving Mechanism are housed in a sheet steel tank, with a flange for mounting on to a port opening on the transformer tank. Leads are to be brought out from the transformer through a Terminal Barrier Board. The Tapchanger must be connected to a conservator through an Oil Surge Operated Protective Relay. The Terminal Board and Oil Surge Operated Protective Relay form part of Tapchanger supply. The conservator, and oil are not in the scope of supply. The Tapchanger must be filled with oil by the Transformer manufacturer.


Rated Voltage                            : 33kV
Max. System Voltage                      : 38kV
Number of Positions                      :  i) 9 Pos. Linear.
                                           ii) 12 Pos. Linear.
                                          iii) 17 Pos. Linear.
                                           iv) 17 Pos. with Pre Selector. 
                                            v) 23 Pos. with Pre Selector.
Max. Continuous Current                  : 300A (Items i & iv)
                                           200A (Items ii, iii & v)
Number of Phases                         : 3
Max. Operating Step Voltage              : 850V
Max. Operating Voltage over Tapping Range: 14000V (Linear versions)
Max. Operating Voltage over              : 7200V (17 Pos. Tapchanger)
                           fine taps       9500V (23 Pos. Tapchanger)
Max. Operating Voltage over              : 7200V (17 Pos. Tapchanger)
                           Coarse taps     9500V (23 Pos. Tapchanger)
Max. Continuous Voltage to ground        : 38000V
Max. Continuous Voltage between phases   : 38000V
Time per tap change                      : 4 - 6 secs.
Wt. of Tapchanger without oil            : 380 Kgs. .... 420 Kgs.
Wt. of Tapchanger with oil               : 675 Kgs. .... 740 Kgs.
Oil Content                              : 335 lts.(9P)-380 lts.
Transition Switching time                : 70 to 90 Milli secs.


                              Power Freq.     Imp.Voltage 
                              for 1 Minute    of 1.2/50
                              (kV RMS)        Microsecond Wave (kVp)
Between Phases                   70              170
Between Phases and Earth         70              170
Between Adjacent Contacts        25              70
Over Fine Taps                   25              70
Over Pre Selector                25              70


Tapchanger ABS has been Type Tested to IS 8468 (equivalent to IEC 214) at Central Power Research Institute, Bangalore, India and at the Division of High Voltage Engineering, Anna University, Chennai, India.

As part of our Quality Assurance Programme, we conduct several tests at our Works, in a routine manner before despatch. The main test, which goes beyond the requirements of IS 8468, is an operation test for 5000 operations, without the contacts energised. During this test, the Motor is run at its normal voltage, and speed, and is switched on and off for each tap change. This is a very rigorous, and very practical test from the point of view of the user.

Tanks are Leak Tested at an air Pressure of 1Kg/cm.sq. Tanks are sand blasted before painting.

We conduct the following Routine tests.

1. Megger.

2. Contact Resistance.

3. Timing of Contacts.

4. Aux. Circuit 2kV Withstand

As the design and manufacture of our equipment are subject to constant improvement, the product supplied may differ in certain details from the specifications and illustrations.

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