Every CT and PT tested before it leaves — not certified on paper, verified on the bench.
An electrical test bench for instrument transformers is not a single instrument — it is a system. Testing a current transformer requires a stable, adjustable high-current source, a precision burden to load the secondary, a reference standard CT with known accuracy, and a comparator to measure the difference in ratio and phase angle between the unit under test and the reference. Testing a potential transformer requires a high-voltage source, a precision voltage divider, and a similar comparison setup. Sakthi's in-house test facility covers both, with a high-current source to 3000A for CT testing and a high-voltage source to 33 kV for PT testing, calibrated reference standards traceable to NABL-accredited laboratories.
Every instrument transformer that leaves Sakthi's production line passes through this bench: ratio test at 5%, 20%, 100%, and 120% of rated current or voltage; phase displacement check at each accuracy class burden point; insulation resistance measurement; and power-frequency voltage withstand. A test certificate with the actual measured ratio error and phase displacement at each test point is issued with every unit. For customers who specify witnessed factory acceptance testing, our engineers will schedule and conduct testing in the presence of the customer's representative.
Typical applications
Performs ratio, polarity, winding resistance, and insulation resistance tests per IS 2705/3156 for every outgoing unit.
Verifies metering and protection accuracy class against a CPRI-calibrated reference standard CT or PT.
Applies power-frequency and impulse test voltages to verify insulation integrity of CT/PT and panel components.
Provides calibration traceability for all measuring instruments and transformers dispatched from the Sakthi facility.
Tell us your spec. We'll build to it.
Share your ratio, accuracy class, burden and standard — our engineering team will quote the right unit.