Advantages and disadvantages of different CT testing methods

CTA-1000 Series CT Analyzer automatically determines all relevant current transformer values and compares the results with the selected standard, include excitation data, saturation inflection point, remanence coefficient， accuracy limit overcurrent factor, ratio and error data. The device evaluates the current transformer as per the IEC or IEEE standard within seconds with the push of a button.
CT Analyzer facilitates fast and economical on-site testing and calibration of metering and protection current transformers. Manufacturers of current transformers, high voltage transformers and switchgear also use the CT Analyzer for tests during development and production.

Advantages and disadvantages of different CT testing methods
Method	Primary nominal current injection	Primary current injection	Secondary voltage injection	Model-based testing
Setup	Reference transformers and measuring bridges	Test set for current supply and measurement	Test set for voltage output and measurement of voltage and current	Test set for low test signal injection and CT modelling
Usage	Used in factories, calibration laboratories and on-site mounted on a test truck	Used during commissioning if high accuracy is not required	Used during commissioning or maintenance if a simple check of the CT‘s integrity from the secondary side is sufficient	Used in all stages of a CT‘s life
Principle
Safety	Performed with very high currents (nominal and overcurrent magnitudes)	Currents up to 1000 A	Voltages up to 2 kV or more	Output voltages up to 180 V
Accuracy	High accuracy	Insufficient for high-accuracy metering CTs Sensitive to transient distortion if line frequency test signals are being used	Insufficient for high-accuracy CTs Sensitive to transient distortion if line frequency test signals are being used	Suitable for all classes, including class 0.1
Mobility	~ Two tons of equipment (test truck, high-current source, heavy cables, current box, …)	~ 30 kg / 66 lbs (without additional equipment such as a burden box)	~ 20 kg / 44 lbs	~ 9 kg / 20 lbs
Handling	The heavy equipment requires several people to set up and perform the test	Rewiring is required between single tests (for example, ratio, polarity, saturation, winding resistance) Results must be assessed manually	Test results must typically be evaluated manually Special attention has to be given to high-voltage leads and connections	One-button test Integrated report Fast (< 2 min)