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SS III 200 DELTA 12 is an On Load Tapchanger suitable for application at the locations of 11kV, Three phase, Star or Delta connected Transformers. It is a linear gear, requiring a potentiometric tapping arrangement, with a Wander Lead. The Tapchanger has a maximum of 9positions, so that it can be applied to a winding of 8 taps, to give 9 different voltages. The functions of the Tap Selector and Diverter Switch are combined in a Selector Switch. The Selector Switch and its integrally mounted stored energy type Driving Mechanism, are housed in a sheet steel tank, with a Flange suitable for mounting on a port on the Transformer Tank. Leads are directly connected to the fixed contacts which extend through the combined Phase Board-cum Terminal Board, into the Transformer oil space. There is no need for a separate Terminal Barrier Board. The Tapchanger may be connected to a conservator, through an Oil Surge Protective Relay. Conservator and Transformer Oil are not in our scope of supply. The Tapchanger must be filled with oil by the Transformer manufacturer.


Rated Voltage                             : 11kV 
Max. System Voltage                       : 12kV
Number of Positions                       : 9 
Max. Continuous Current                   : 200A.
Number of Phases                          : 3
Peak Emergency Current                    : 300V
Max. Operating Voltage over Tapping range : 6000V
Max. Continuous Voltage to ground         : 12000V
Max. Continuous Voltages between phases   : 12000V
Time per tap change                       : 6 secs(approx.)
Wt. of Tapchanger without Oil             : 250 kgs.
Wt. of Tapchanger with Oil                : 335 kgs.
Oil Content                               : 98 lts. (approx.)
Transition Switching time                 : 20-30 Milli Secs.


Between Phases                   28                  75
Between Phases and Earth         28                  75
Between Adjacent Contacts        20                  50
Across Tapping Range             25                  70


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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