Equipment under Measurement: 6.6kV Alstom AIS Switchgear. Date of Measurement: 10 th August 2017

Transcription

1 Case History - 24: Online PD measurement using TEV, Ultrasonic Inductive UHF & HFCT Sensors Equipment under Measurement: 6.6kV Alstom AIS Switchgear Date of Measurement: 10 th August 2017 Sensor Used: (i) TEV Sensor (ii) Ultrasonic Sensor (iii) Inductive UHF Sensor (iv) HFCT Sensor

2 LINE PD MEASUREMENT RESULT (BEFORE CLEANING) USING SNAPSHOT TEV SENSORS Client : A Sensor Used: TEV Sensor Manufacturer: Alstom Type: AIS Measurement Date : 10 th August 2017 Phase Resolved TEV Magnitude = 17dB Pulse per Cycle = dB/ dB/ dB/ dB/ dB/ dB/2.91 To Transformer Generator Supply from Gen rom S/S 3 Bus Section From S/S 2 PG Supply From Raw Water Pumping Station PG Supply 13dB/ dB/ dB/ dB/ dB/1.54 PRPD Analysis => Two clusters in 180 degree apart which is characteristics of PD activity Time Domain Waveform Time Domain Waveform (Waveform 1) No. of waveform: 34 Conclusion : PD detected

3 LINE PD MEASUREMENT RESULT (AFTER CLEANING) USING SNAPSHOT TEV SENSORS Client : A Sensor Used: TEV Sensor Manufacturer: Alstom Type: AIS Measurement Date : 04 th September 2017 Phase Resolved TEV Magnitude = 3dB Pulse per Cycle = 0 7dB/0 7dB/0 5dB/0 6dB/0 6dB/0 3dB/0 To Transformer Generator Supply from Gen rom S/S 3 Bus Section From S/S 2 PG Supply From Raw Water Pumping Station PG Supply 6dB/0 15dB/ dB/0.26 9dB/0 8dB/0 PRPD Analysis => Two clusters in 180 degree apart which is characteristics of PD activity Time Domain Waveform Time Domain Waveform (Waveform 1) No. of waveform: 3 Conclusion : PD detected

4 LINE PD MEASUREMENT RESULT (BEFORE CLEANING) USING SNAPSHOT ULTRASIC SENSORS Client : A Sensor Used: Ultrasonic Sensor Manufacturer: Alstom Type: AIS Measurement Date : 10 th August dBµV -4dBµV -4dBµV -3dBµV -4dBµV S1 10dBµV 5dBµV S2 To Transformer Generator Supply from Gen rom S/S 3 Bus Section From S/S 2 PG Supply From Raw Water Pumping Station PG Supply -2dBµV -3dBµV -4dBµV -3dBµV -3dBµV Phase Resolved Ultrasound (S1) Phase Resolved Ultrasound (S2) Audio Analysis => Suspect Abnormal/Cracking Sound detected. Audio Analysis => Suspect Abnormal/Cracking Sound detected.

5 LINE PD MEASUREMENT RESULT (AFTER CLEANING) USING SNAPSHOT ULTRASIC SENSORS Client : A Sensor Used: Ultrasonic Sensor Manufacturer: Alstom Type: AIS Measurement Date : 04 th September dBµV 0dBµV -3dBµV -3dBµV -3dBµV S1-2dBµV -1dBµV S2 To Transformer Generator Supply from Gen rom S/S 3 Bus Section From S/S 2 PG Supply From Raw Water Pumping Station PG Supply -3dBµV -3dBµV -3dBµV -1dBµV -3dBµV Phase Resolved Ultrasound (S1) Phase Resolved Ultrasound (S2) Audio Analysis => No Abnormal/Cracking Sound detected. Audio Analysis => No Abnormal/Cracking Sound detected.

6 INDUCTIVE UHF & HFCT CNECTI DIAGRAM Inductive UHF Connection Diagram HFCT Connection Diagram Gen supply from Gen Room to s/s 3 G From s/s 2 PG supply From Raw Water Pumping Station PG Supply Gen supply from Gen Room to s/s 3 G From s/s 2 PG supply From Raw Water Pumping Station PG Supply 6.6kV AIS Inductive UHF sensor (100MHz ~ 450MHz) connected to body earth of the 6.6kV AIS 6.6kV AIS HFCT (Omicron) Sensor (100 khz ~ 20MHz) Connected to the body earth of 6.6kV AIS 1 1 PD TEST SET PD TEST SET Transformer Transformer

7 LINE PD MEASUREMENT RESULT (BEFORE CLEANING) USING SNAPSHOT INDUCTIVE UHF SENSORS Client : A Sensor Used: Inductive UHF Sensor Manufacturer: Alstom Type: AIS Measurement Date : 10 th August 2017 Ultra-High Frequency Sweep and Location of center frequency PRPD Pattern (Fc=412.5 MHz, BW=70MHz) (Fc=265.5 MHz, BW=70MHz) (Fc=148 MHz, BW=70MHz)

8 LINE PD MEASUREMENT RESULT (AFTER CLEANING) USING SNAPSHOT INDUCTIVE UHF SENSORS Client : A Sensor Used: Inductive UHF Sensor Manufacturer: Alstom Type: AIS Measurement Date : 04 th September 2017 Ultra-High Frequency Sweep and Location of center frequency PRPD Pattern (Fc=435 MHz, BW=70MHz) (Fc=277 MHz, BW=70MHz) (Fc=140 MHz, BW=70MHz)

9 LINE PD MEASUREMENT RESULT (BEFORE CLEANING) USING SNAPSHOT HFCT SENSORS Client : A Sensor Used: HFCT Sensor Manufacturer: Alstom Type: AIS Measurement Date : 10 th August 2017 FFT Graph Cluster 1_Filter 1 (F1=1 MHz, BW=160kHz) 3 Center Frequency Relation Diagram Cluster 1_Filter 2 (F2=2.2 MHz, BW=160kHz) Cluster 1_Filter 3 (F3=6.3 MHz, BW=160kHz) Cluster 1 500fC

10 LINE PD MEASUREMENT RESULT (AFTER CLEANING) USING SNAPSHOT HFCT SENSORS Client : A Sensor Used: HFCT Sensor Manufacturer: Alstom Type: AIS Measurement Date : 04 th September 2017 FFT Graph Cluster 1_Filter 1 (F1=1.002 MHz, BW=160kHz) 3 Center Frequency Relation Diagram Cluster 1_Filter 2 (F2=5.239 MHz, BW=160kHz) Cluster 1_Filter 3 (F3=15.53 MHz, BW=160kHz) Cluster 1 1pC

11 FINDING Shut down inspection was done on 31st August Discolouration seen all around circuit breaker s L2 lower bar insulation. Bad insulation quality seen at busbar joints or all phase.

12 OBSERVATI DURING SHUT DOWN

13 OBSERVATI DURING SHUT DOWN