Power Generation, Distribution & Reliability

S.No. Area Title Description Action Status
1 11 KV, HT panel While working in cable termination chamber of 11 kV HT incomer where cable has failed, a lizard entered into the HT panel via the cable termination chamber door and caused a flashover in adjacent outgoing feeder. We would like to know if any work procedure exists to avoid Vernon entry into HT panels exists while carrying out jobs on rear cable tension chambers.
2 Switchgear failure A power failure occurred at 33 kV generation switchgear (2 nos. of 25 MW GTGs are connected) due to tracking of bus coupler breaker pole bottom assembly. This resulted in operation of bus differential relays of both section A and Section B causing all breakers in the switchgear to trip. Owing to critical nature of the switchgear the bus coupler breaker was not taken for maintenance checks over last 10 years. The substation is an air conditioned substation. Upon review by OEM M/s Siemens it was concluded that the issue is due to accumulation of dust and moisture on the pole of the breaker. Similar issues in other refineries may be reviewed for identifying root cause and preparing best maintenance practices for critical generation and distribution switchgear.
3 NIDEC ( ANSALDO),Italy make VFDs HPCL , Viskah Refinery has 6.8 MW ,6.6 KV , VFD of Nidec ,Italy make for RG Compressor of DHT unit .There are frequent failure of VFD control card (FLTCTL card ). Request to give feedback on failure of control cards if any with mitigation taken . Also we have provision for on line changeover from VFD to DOL and vice versa. Recently we had one failure during changeover from DOL to VFD mode. Pls. provide feedback on performance of changeover scheme .