Monitoring, Control and Communications for Electrical Power Apparatus
Analysis of Partial Discharges Detected in 420kV Oil Impregnated Paper Bushings
Mark Tostrud
Dynamic Ratings, Inc
17th, May 2017
Monitoring, Control and Communications for Electrical Power Apparatus
Offline Power Factor Tests – 420 kV OIP BushingsBushing Date Tanδ at 10kV
C1 C2Capacitance at 10kVC1 C2
H1 Nameplate 0.31 439Commissioning 0.30 0.32 434 382729.11.14 0.26 0.32 438 3825
H2 Nameplate 0.30 438Commissioning 0.30 0.27 435 347129.11.14 0.26 0.50 436 3473
H3 Nameplate 0.39 443Commissioning 0.33 0.33 440 494629.11.14 0.34 0.29 442 4942
Monitoring, Control and Communications for Electrical Power Apparatus
Typical bushing and partial discharge monitoring system installation for high voltage reactors:• Bushing sensors installed in the
capacitive tap of the bushing –primary sensor for the system
• Rogowski coils installed near the bottom flange of the bushing –secondary sensor for the system
400kV 3 Phase 125 MVAR Shunt Reactor Bushing & PD Installation
Monitoring, Control and Communications for Electrical Power Apparatus
Phase 1 Bushing DGA Data
Date H2 CH4 C2H4 C2H6 C2H2 CO CO2
Bushing H1 (ppm)
April 15 2014 17 2 3 0 0 60 356
Nov 29 2014 625 46 0 7 0 95 513
Jan 7 2015 1262 88 4 16 0 95 515
Feb 14 2015 2378 147 1 26 2 104 512
Monitoring, Control and Communications for Electrical Power Apparatus
Phase 1 Bushing – Duval Pentagon 1Analysis
Monitoring, Control and Communications for Electrical Power Apparatus
400kV 3 Phase 125 MVAR Shunt Reactor PD Analysis – Bushing 1
Monitoring, Control and Communications for Electrical Power Apparatus
OIP Bushing - Lower Inner Porcelain Partial Discharge Signature
Lower porcelain contamination
Monitoring, Control and Communications for Electrical Power Apparatus
Phase 2 Bushing DGA Data
Date H2 CH4 C2H4 C2H6 C2H2 CO CO2
Bushing H2 (ppm)
April 15 2014 15 0 3 0 0 63 177
Nov 29 2014 47 2 0 1 0 110 249
Jan 7 2015 361 16 4 0 0 82 224
Feb 14 2015 1180 111 30 26 0 54 287
Monitoring, Control and Communications for Electrical Power Apparatus
Phase 2 Bushing – Duval Triangle 4 Analysis
Monitoring, Control and Communications for Electrical Power Apparatus
400kV 3 Phase 125 MVAR Shunt Reactor PD Analysis – Bushing 2
Monitoring, Control and Communications for Electrical Power Apparatus
Phase 3 Bushing DGA Data
Date H2 CH4 C2H4 C2H6 C2H2 CO CO2
Bushing H3 (ppm)
April 15 2014 42 0 4 0 0 77 526
Nov 29 2014 72 2 0 0 0 151 903
Jan 7 2015 50 2 2 0 0 123 891
Feb 14 2015 54 3 2 0 0 135 944
Monitoring, Control and Communications for Electrical Power Apparatus
Phase 3 Bushing – All gases are normal
Monitoring, Control and Communications for Electrical Power Apparatus
● Online partial discharge monitoring can successfully identify bushing health problems
● The phase resolved data patterns provide a useful information to assess the type of failure that may be occurring in the bushing
● Understanding the failure modes of the equipment being monitored can help users better analyze the data from the monitor
● Transformer and reactor designs can significantly influence the electrical fields to which bushings are subjected
● Bushings can degrade very rapidly and the use of an online monitoring system can provide the data needed to make an informed decision on the asset health
Conclusions
Monitoring, Control and Communications for Electrical Power Apparatus
Questions / Discussion