conditional based maintenance with on- line partial discharge measurements of hv and mv switchgear...

Conditional Based Maintenance with On-line Partial Discharge Measurements of HV

and MV Switchgear Systems

Presented by J.J. Smit

R.G.A. Zoetmulder, S. Meijer and J.J. Smit

Question number 8

Introduction and GoalInsulation test:1: Detection2: Defect identification3: Defect localization4: Risk assessment

Goal:

- Medium Voltage Gas Insulated Systems (MV-GIS) - Medium Voltage Air Insulated Systems (MV-AIS)- Medium Voltage Oil Insulated Systems (MV-OIS)

To apply the UHF measuring technique used for High Voltage Switchgear (HV GIS) also for :

The measuring system

• Broadband detection > UHF (till several GHz)

• With this method noises can be suppressed by measuring at a frequency band with a low noise-level

* Hard-ware

Components:1 a: Internal UHF coupler1 b: external UHF coupler2 : Pre-amplifier3 : Spectrum analyzer4 : Computer

10 kV Air Insulated Switchgear system-1- 10 kV Air Insulated

- Vacuum Circuit-Breaker

- Measuring locations are small inspection windows

- UHF signals can propagate through these inspection windows and can than be detected

Front-side Back-side

Advanced stadium(More affected)

Begin stadium

(less affected)

Surface discharge at one of the phase connectors of the circuit-breaker

10 kV Air Insulated Switchgear system-2

Conclusions

Measurements with the external UHF coupler are applicable to medium voltage switchgear installations, e.g. air insulated switchgear, as well as to HV switchgear systems.

Using advanced PD analysis techniques distinction can be made between the different patterns detected by the external UHF coupler.

UHF PD measurements can contribute to CBM procedures.

With UHF PD measurements one can also determine the position of system design errors, which then can be corrected.