The effect of induced voltage withstand and external processing frequency high voltage on transformers is different. In the "Electrical Equipment Handover Test Standard", it is stipulated that on-site measurement of induced voltage withstand and local discharge capacity of transformers is required for the installation of power transformers in 220kV systems.
The function and purpose of induction withstand voltage for power transformers are described as follows:
(1) Effectively check the longitudinal insulation of fully insulated power transformers;
(2) Can test the partial main insulation and longitudinal insulation of graded insulation transformers;
(3) Can effectively test the voltage resistance of the transformer's longitudinal insulation;
(4) For graded insulation transformers with different insulation levels at the beginning and end, the use of induction voltage withstand test can effectively reflect the insulation strength;
(5) By using the non measured phase winding to support the tested winding and raise the neutral point position, both the main insulation and longitudinal insulation tests can be met simultaneously.
The induction voltage withstand test of transformers on site is generally measured using the self coupling method, using lower windings or non tested windings of the same voltage level to support the tested high-voltage winding. The voltage is both easy to reach the test voltage and easy to control, which is currently a commonly used measurement method in the power sector.