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Partial Discharge Diagnostic of Medium Voltage Switchgear under Operating Conditions using a special PD- Probe. Quality Control Stages of MV GIS and PD - Measurement. demands high sensitivity ( ~ pC) failure identification failure location. development manufacturing
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Partial Discharge Diagnostic of Medium Voltage Switchgear under Operating Conditions using a special PD- Probe
Quality Control Stages of MV GIS and PD - Measurement • demands • high sensitivity ( ~ pC) • failure identification • failure location development manufacturing assembling transport/ on site assembling operation pd- measurement pd data base (pc- based system) PRPD pattern
Phase- Resolved-PD- (PRPD) Pattern measured parameter: q (U, φ, t, ….) acc. to CIGRE- format)
PRPD- Pattern of a defect part PD pattern of a separation between the insert and the cast resin at the grounded side of a 36-kV-spacer
special problems for on- site- diagnosis • demand for no- switching- off of operational voltage, but compatibility to pd- test procedures during manu- facturing process measuring ofPRPD- pattern for comparison with reference pd- data- base seems to be necessary calibrating procedures are necessary (unconventional measuring methods like acoustical/ optical methods are not sufficient) coupling elements are necessary
Typical measurement conditions for on- site- testing pd´s superimposed with large distur- bances caused by near located SFC pd- spectra with disturbances
special problems for on- site- diagnosis • requirement of high measuring sensitivity special requirements/ procedures for suppressing of noise/ disturbances
pd- on- site measurement by electromagnetic field coupling
transfer characteristic of pd- probes (UHF- measurement) UHF- Measurement [acc. to IEC 60270]
diagnostic- object: medium voltage switchgear capacitive sensor user- table h.v. joints 36kV GIS- substation modules
measuring sensitivity with capacitive sensor coupling equivalent test circuit q- sensitivity is non sufficient
medium voltage switchgear with additional cable- parts capacitive sensor user- table h.v. joints cable- parts
transfer characteristic with additional cable- parts test circuit transfer characteristic
pd calibration with and without connected power cable • with power cable • classical pd- meas. system • - pd- probe without power cable
diagnosis results capacitive sensor pd probe and measuring impedance defect spacer
conclusions • pd measurements are up to now an essen- tial tool for quality testing of electrical insulation even for on- site diagnosis • demanding for no- switching- off of operation voltage during the testing leads to non classical measurement methods (UHF- measurement by special pd- probes)
if into the switchgear a capacitive sensor is available, so by using a special pd- probe sensitive PD- on site- tests can be provided • the measuring sensitivity can be increased significantly by using of appropriate resonance elements like cabel- parts • this testing arrangement can be used in principle even for similar configurations.
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