Principle of operation

The Potential Transformer is a "Parallel Transformer" with its secondary operating under virtual open- circuit conditions (Potential Transformer burdens are of relatively high impedance) where as a Current Transformer is a "series" Transformer whose secondary operates under virtual short circuit conditions (Current Transformer burdens are of relatively low impedance). The design is controlled by considerations of adequate insulation and good regulation.

Ratio & Phase angle Formulas.

The Potential Transformer shall be as far as possible an "Ideal" Transformer i.e. the secondary voltage vector is exactly equal to primary voltage vector multiplied by the turns ratio. But errors are introduced due magnetization of the core and because of leakage reactance and winding resistance.

The DESIGN features of INDUS are in such away that the drops due to leakage reactance and winding resistance are minimized. It also use best grades of CRGO steels which enables optimum levels magnetic flux for minimum phase angle variation and low cost.

Outdoor CT PT Assembling
Outdoor PT Assembling
Meters and Testing Equipments:


Some of the machineries used for Testing are
1. Automatic CT PT Unit Testing Machines
2. Standard CTs and PTs
3. Precision Type Tong Testers
4. Precision Voltmeters and ammeters
6. Vacuum Mixing Machines
7. acuum Filling Machines
8. Auto Transformers
9. Multimeters
10. High Frequency Generator
11. High Voltage Insulation Tester
12. High Voltage Oil Testing Machine


Sri. M.N. Rajappan, M.Tech, Addl.Chief Electrical Inspector (Rtd)-Managing Director
Sri. P.C. Rajanbabu, Chief Electrical Inspector (Rtd) - Technical Consultant
Sri M.G.Rajagopal Chief Electrical Inspector (Rtd) – Director
Sri.Krishna Kumar (Electrical Consultant) – Director
Smt. Divya B.Tech, M.B.A – Director

Technical information on Selection, Design and Installation of Instrument Transformers –
Will be available on contacting by email -