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ABS III 150 60 is an On Load Tapchanger suitable for application at the graded neutral end of 132kV, Three phase, Star connected Transformers. It is a tapchanger equipped with a Pre Selector, and will, therefore, suit either a Reversing, or a Coarse/Fine tapping arrangement, with a Wander Lead. The tapchanger is equipped with symmetrical resistances, and auxiliary switching contacts, giving rise to the symmetrical flag cycle of transition. Therefore, the tapchanger is suitable for bidirectional power flow to the fullest extent of its ratings. The tapchanger gives 17 different voltages, when connected to 8 Fine Taps, with either an 8 Step Coarse Tap, or by reversing the fine tap winding. The functions of the Tap Selector and Diverter Switch are combined in a Selector Switch. The Selector Switch and its integrally mounted stored energy on the Transformer Tank leads can be brought out of the Transformer through a Port Flange mounted, on the Transformer tank. Leads can be brought out of the Transformer through a Port Flange mounted, oil tight, Terminal Barrier Board, which is part of the Tapchanger Supply. The Tapchanger must be connected to a conservator, through an Oil Surge Protective Relay. The Oil Surge Protective Relay forms part of Tapchanger supply, but the conservator and Transformer Oil are not in the scope of supply. The Tapchanger must be filled with oil by the Transformer manufacturer.


Rated Voltage                           : 132kV (Graded Neutral).
Max. System Voltage                     : 85kV
Number of Positions (Max.)              : 17 (Non Linear)
Max. Continuous Current                 : 150A.
Number of Phases                        : 3
Max. Operating Step Voltage             : 1800V
Max. Operating Voltage over Fine taps   : 14000V
Max. Operating Voltage over Coarse taps : 14000V
Max. Continuous Voltage to ground       : 85000V
Time per tap change                     : 4-6 secs.
Wt. of Tapchanger without Oil           : 650 kgs.
Wt. of Tapchanger with Oil              : 1810 kgs.
Oil Content                             : 1400 lts. (approx.)
Transition Switching time               : 110 to 140 milli secs


                                    Power Freq.     Imp. Voltage
                                    for 1 Minute    of 1.2/50 Microsec
                                    (kV RMS)        Wave (kVp).
Tapchanger to earth                   140             350
Between Adjacent Contacts             45              200
Over Pre Selector                     45              200
Between Pre Selector & Fine Selector  45              250


This Tapchanger has been Type Tested to IS 8468 (equivalent to IEC 214) at CPRI., and at the Division of High Voltage Engineering, Anna University, Madras.

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/cm2. Tanks are Sandblasted 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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