Download Sensitivity measurements

Conditional Based Maintenance with Online Partial Discharge Measurements of HV
and MV Switchgear Systems
R.G.A. Zoetmulder, S. Meijer and J.J. Smit
Presented by
J.J. Smit
Question number 8
Introduction and Goal
Insulation test:
1: Detection
2: Defect identification
3: Defect localization
4: Risk assessment
Goal:
To apply the UHF measuring technique
used for High Voltage Switchgear (HV GIS) also for :
- Medium Voltage Gas Insulated Systems (MV-GIS)
- Medium Voltage Air Insulated Systems (MV-AIS)
- Medium Voltage Oil Insulated Systems (MV-OIS)
The measuring system
* Hard-ware
• Broadband detection >
UHF (till several GHz)
• With this method noises
can be suppressed by
measuring at a frequency
band with a low noise-level
Components:
1 a: Internal UHF coupler
1 b: external UHF coupler
2 : Pre-amplifier
3 : Spectrum analyzer
4 : Computer
10 kV Air Insulated Switchgear system-1
- 10 kV Air Insulated
- Measuring locations are
small inspection windows
- Vacuum Circuit-Breaker
- UHF signals can propagate
through these inspection
windows and can than be
detected
Front-side
Back-side
Begin stadium
(less affected)
Advanced stadium
(More 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.