With the continuous development of UHV transmission technology

the rated voltage of impulse voltage measuring system has risen up to 7 000 kV for satisfying the withstand test requirements of electric devices.Based on the situation

the linearity measurement of impulse voltage measuring system above 1 000 kV is a problem needed to be resolved urgently since the calibrating voltage is below 1 000 kV which can’t be well positioned to meet the actual experimental requirements.The paper analyzes two existing calibration methods which are direct comparison calibration and capacitance measurement of dividers

and provides a testing plan to compare calibration when the voltage below 1 000 kV and to compare each level by increasing the voltage step by step when the voltage between 1 000 kV and 5 000 kV with measuring changes in generator efficiency as a proof.In theory

the plan can basically satisfies the engineering tests of 7 500 kV impulse voltage measuring system with the voltage is 1 000 kV to 5 000 kV.If the test results are satisfactory

a transfer standard can be built by the method in paper to compare all UHV impulse measuring systems in nation.The paper also introduces some other methods of measuring linearity such as sphere gap

standard capacitor

space charge

and field sensor.By discussing the methods’ respective advantages and disadvantages

they need further experimental verifications for practical application.