Variable Frequency Series AC Resonant Test System for on-site AC withstand voltage test of GIS
Currently,there are three types of test equipment used for on-site communication voltage withstand tests for GIS,namely power frequency test transformers,inductive Variable Frequency Series AC Resonant Test System,and frequency modulation Variable Frequency Series AC Resonant Test System.
Due to their large and bulky equipment and difficult on-site transportation,power frequency test transformers are generally only suitable for on-site testing of GIS with a voltage level of 110 kV.During the test process,if the tested object undergoes flashover or breakdown,the short-circuit current is extremely prone to burn the tested object.
Since the advent of Variable Frequency Series AC Resonant Test System,power frequency test transformers have rarely been used as voltage withstand equipment on-site.The inductive series resonance voltage withstand test device uses a high-voltage reactor with adjustable iron core air gap,which has the disadvantages of loud noise,complex mechanical structure,heavy equipment,and difficult transportation.
However,the test voltage frequency is generally power frequency.The frequency modulation series resonance voltage withstand test device uses a fixed high-voltage reactor,and the test circuit is powered by a controllable silicon frequency conversion power supply device with a frequency adjustable within a certain range.It is characterized by small size,light weight,high quality factor,and can be tested with electromagnetic voltage transformers simultaneously.It has no test dead zone,but the test voltage frequency is not power frequency.Due to the large number of electronic components in the frequency conversion power supply device,its reliability is slightly inferior.
The specified test voltage should be applied between each phase conductor and the metal enclosure,with only one phase being pressurized at a time,while the other phase conductors are connected to the grounded metal enclosure.When the test power supply capacity is limited,the GIS can be disconnected into several parts using its internal circuit breaker or disconnecting switch for testing separately,while the non-tested parts should be grounded,and it should be ensured that the voltage on the circuit breaker fracture,fracture capacitor or disconnecting switch fracture does not exceed the allowable value.
Due to their large and bulky equipment and difficult on-site transportation,power frequency test transformers are generally only suitable for on-site testing of GIS with a voltage level of 110 kV.During the test process,if the tested object undergoes flashover or breakdown,the short-circuit current is extremely prone to burn the tested object.
Since the advent of Variable Frequency Series AC Resonant Test System,power frequency test transformers have rarely been used as voltage withstand equipment on-site.The inductive series resonance voltage withstand test device uses a high-voltage reactor with adjustable iron core air gap,which has the disadvantages of loud noise,complex mechanical structure,heavy equipment,and difficult transportation.
However,the test voltage frequency is generally power frequency.The frequency modulation series resonance voltage withstand test device uses a fixed high-voltage reactor,and the test circuit is powered by a controllable silicon frequency conversion power supply device with a frequency adjustable within a certain range.It is characterized by small size,light weight,high quality factor,and can be tested with electromagnetic voltage transformers simultaneously.It has no test dead zone,but the test voltage frequency is not power frequency.Due to the large number of electronic components in the frequency conversion power supply device,its reliability is slightly inferior.
The specified test voltage should be applied between each phase conductor and the metal enclosure,with only one phase being pressurized at a time,while the other phase conductors are connected to the grounded metal enclosure.When the test power supply capacity is limited,the GIS can be disconnected into several parts using its internal circuit breaker or disconnecting switch for testing separately,while the non-tested parts should be grounded,and it should be ensured that the voltage on the circuit breaker fracture,fracture capacitor or disconnecting switch fracture does not exceed the allowable value.
