220KV EHV NETWORK

AT

RELIANCE JAMNAGAR

REFINERY

COMPLEX

JAMNAGAR 220KV CABLE NETWORK:

2

2. DESIGN

2A. NETWORK:

220 KV NETWORK DESIGN IS DESIGNED WITH 100% REDUNDANCY FROM 220 KV BUS TO LOAD.

THIS IS ACHIEVED WITH DUAL 220 & 33 KV BUSBARS, DUAL 220 AND 33 KV TRANSFORMERS AND

DUAL 220 & 33 KV CABLE NETWORKS.

2B: 220 KV CABLE DESIGN

TWO TYPES OF CABLE CIRCUITS WERE IDENTIFIED TO CATER TO THE NETWORK

TYPE -1-174 MVA CAPABILITY: SINGLE CORE 400SQ.MM XLPE COPPER CONDUCTOR CABLE ISSELECTED TO LAY IN FLAT FORMATION.

TYPE-2- 300MVA CAPABILITY: SINGLE CORE 1000SQ.MM XLPE COPPER CONDUCTOR CABLE IS SELECTED TO LAY IN FLAT FORMATION.

3

CABLE SHEATH: LEAD SHEATH IS USED TO PROTECT THE CABLE INSULATION FROM SOLVENTS PRESENT IN THEUNDERGROUND SOIL IN THE REFINERY AND PETROCHEMICAL COMPLEX.

CABLE DESIGN PARAMETERS:

CABLE 400SQ.MM CABLE 1000SQ.MM CABLE

CONDUCTOR COPPER COPPER

INSULATION XLPE XLPE

METALLIC SHEATH LEAD ALLOY LEAD ALLOY

METALLIC SHEATH THICKNESS 1.9MM 2.0MM

OVERALL DIAMETER 97MM 108MM

WEIGHT 16.6 KG/M

CABLES LAID QUANTITY OF 400&1000SQ.MM 140KM

TRENCHES LAID 24KM

4

EXECUTION

AT CRITICAL LOCATIONS WHERE VEHICLE MOVEMENT CANNOT BE STOPPED AND AT THE SAMETIME DUCTING WORK WAS SUPPOSED TO BE CARRIED OUT, HDD (HORIZONTAL DIRECTIONDRILLING) METHOD WAS ENVISAGED. DURING HDD JOB SOIL STRATA WAS NOT CONDUCIVE DUETO SOLID ROCK BELOW 1METER OF THE SURFACE AND DUE TO WHICH DRILL FAILED AT SEVERALINSTANCES.

5

SITE ACCEPTANCE TESTS

ONCE ALL THE CABLE IS LAID THE CABLE IS TESTED WITH ALL ACCEPTANCE PROCEDURES TOSUCCESSFULLY CHARGE THE CABLE AS PER VENDOR GUIDELINES AND IEC

INSULATION RESISTANCE TEST

DC CONDUCTOR RESISTANCE TEST

LINK BOX CONTACT RESISTANCE TEST:

SVL INSULATION TEST:

DC JACKET TEST:

24 HR. SOAK TEST: THIS TEST WAS PERFORMED TO ENSURE THAT THE CABLE LAID AND CHARGED

ON NO LOAD IS FREE FROM ALL DEFECTS

PARTIAL DISCHARGE MEASUREMENT TEST: CAPACTIVE TYPE PD MEASUREMENT SYSTEM IS

BEING USED

CASE STUDIES: CASE STUDY-1

220KV CABLE INTERCONNECTED BETWEEN 220KV GIS MRS 4 AND C2 COMPLEX MRS-1 WAS

TRIPPED AFTER WAS SUCCESSFULLY CHARGED IN JULY’16

THE CABLE FAULT COULD NOT BE LOCATED EVEN WITH 33KV CABLE FAULT LOCATOR. CABLE WAS

TESTED BY KEEPING 2X105MVA POWER TRANSFORMER IN SERIES HAVING AN IMPEDANCE VALUE

OF 13.25% AND THEREBY LIMITING THE FAULT CURRENT TO 1KA.

NO. OF TIMES SUCH TESTING WAS CARRIED OUT, BUT CABLE IR VALUE IS FOUND NORMAL. LATER

IT WAS DECIDED TO DISCONNECT THE CABLE FROM GIS TERMINATION AND TEST THE CABLE WITH

SWITCH ON TO FAULT LOCATION.

LATER THE FAULT WAS FOUND IN GIS AND WAS VT FAILURE SIEMENS SENT VT TO WORKS

IMMEDIATELY FOR INVESTIGATION. TRACKING WAS VISIBLE ON THE EPOXY GAS TIGHT BUSHING

INSIDE VT TANK. UPON RELIANCE INSTRUCTIONS HV TEST WAS PERFORMED ON THE SAME.

7

CASE STUDY 1 CONTINUED….

8

CASE STUDY-2:

ROUTE-3 1000SQ.MM CABLE RUNNING FROM DTA MRS4 TO C2 MRS-1 CABLE TRIPPED ON JUNE16,

2HOURS AFTER CHARGING.

CABLE FAULT WAS LOCATED WITH THE HELP OF CABLE FAULT LOCATOR AND WAS 58M AWAY FROM ONE

OF THE JUNCTION IN SINGLE (RED) PHASE FROM MRS4.

SITE INSPECTION REVEALED PHYSICAL DAMAGE TO THE CABLE.

A SHARP PHYSICAL DAMAGE WAS ALSO OBSERVED ON THE INSULATION.

FURTHER TO THIS INCIDENT ALL THE METALLIC SHOVELS WERE REPLACED WITH PLASTIC TO AVOID PHYSICAL

DAMAGE TO THE CABLE

9

CASE STUDY-3

CABLE DIAMETER DIAMETER OVER

INSULATION

STRESS CONE

RECEIVED AT SITE

NEW STRESS CONE

ENVISAGED

1000 SQ.MM 83.9MM 76.5MM TO 81.5MM 81MM TO 85.5MM

400 SQ.MM 74.1MM 67.5MM TO 72.5MM 72MM TO 75MM

400 SQ.MM WITH DIAMETER OVER INSULATION BEING 74.1MM AND 1000 SQ.MM CABLE WITH

DIAMETER OVER INSULATION 83.9MM.

STRESS CONE USED AS A PART OF 220KV GIS CABLE TERMINATION DID NOT MATCH WITH THE

DIAMETER OF THE CABLE RECEIVED AT SITE. STRESS CONE SUPPLIED

FOR 400SQ.MM VARIED BETWEEN 76.5MM-81.5MM WHICH WAS NOT SUITABLE TO THE CABLE

SUPPLIED.

10

CASE STUDY 4

CABLE BETWEEN STG TRANSFORMER AND 220KV GIS WAS CHARGED IN THE MONTH OF

MAY 17.

MINOR SPARK NEAR SUPPORT CLAMP AT THE TIME OF CLOSING THE BREAKER TO

ENERGIZE THE CABLE.

MANUFACTURER PERFORMED SWITCHING OVERVOLTAGE STUDY TO INVESTIGATE THE

TRANSIENT STATE ASSOCIATED WITH THE ROUTE. BY EMTP SIMULATION APPROXIMATELY

THE INDUCED VOLTAGE ONTO THE SURFACE OF THE CABLE WAS 300-600V. THIS SURFACE

VOLTAGE OF CABLE RESULTED IN SPARK PHENOMENA BETWEEN CABLE

THE INSULATOR/RUBBER CUSHION IN BETWEEN CABLE CLEAT AND CLAMP HAS NOT BEEN

PROPERLY LOCATED TO INSULATE THE CABLE FROM THE CLAMP

11

SAT WITH EHV TEST KIT

RELIANCE PROCURED THE DAC 300 MEGGER KIT TO TEST EHV CABLES AS SOAK TEST IS GETTING DIFFICULT

DUE TO RELIABILITY OF THE NETWORK.

THE SELECTION OF THIS TEST KIT IS MAINLY DUE TO PORTABLE IN NATURE AND PD TESTING IS POSSIBLE.

HV TEST KIT IS COMMISSIONED IN AUGUST 2017.)

12

TEST KIT INSIDE GIS

TEST KIT OUTDOOR

MAINTENANCE PROCEDURES LAID FOR RELIABLE OPERATION.:

THE 220KV CABLE NETWORK LAID ACROSS THE PLANT IS THE HEART OF THE PROJECT AND ANY

HINDRANCE TO THE POWER SUPPLY SHALL HAVE HUGE FINANCIAL EFFECTS TO THE PLANTS

DEPENDING ON THIS NETWORK. SO PREVENTIVE MAINTENANCE IS ONLY SOLUTION TO AVOID ANY

SHUTDOWNS.

FOLLOWING IS THE SUMMARY OF MAINTENANCE ACTIVITIES PERFORMED.

SR. NO. ACTIVITY DETAIL OF ACTIVITY FREQUENCY

1 ROUTE SURVEY

UNDERGROUND: LOOK FOR ANY EXCAVATION JOBS (MANUAL/MECHANIZED) NEAR TRENCHES, STORAGE OF MATERIALS OVER CABLE TRENCH, CONDITION OF ROUTE MARKERS, EXPOSURE OF CABLE TILES DUE TO SOIL EROSION DURING MONSOON.ABOVE GROUND: THIS IS A PATROL CHECK ALONG WHOLE CABLE ROUTE LINE EXPOSED IN THE AIR TO INVESTIGATE CONDITION OF CABLE AND SURROUNDING CONDITION OF ROUTE TO ASSESS PHYSICAL DAMAGE, ARCING OR TRACKING TRACES.

WEEKLY

2 THERMOGRAPHIC INSPECTIONS ONLINE: THERMOGRAPHY TO BE CARRIED OUT FOR AIS END TERMINATIONS AND SUPPORT STRUCTURE/TRAYS FOR IDENTIFYING LOCAL HEATING.

26 WEEKS

3PARTIAL DISCHARGE (PD) MEASUREMENT

ONLINE: MEASUREMENT OF PARTIAL DISCHARGES TO THE RATED OPERATING VOLTAGE USING PD SENSORS.

OFFLINE: MEASUREMENT OF PARTIAL DISCHARGE USING EXTERNAL VOLTAGE SOURCE BY MEGGER DAC 300.

26 WEEKS

5 YEARS

13

4SHEATH CURRENT MEASUREMENT

ONLINE: MEASUREMENT OF SHEATH CIRCULATING CURRENT, TO ASSESS HEALTHINESS. THIS MEASUREMENT WILL REVEAL SHEATH PROBLEMS LIKE EXTERNAL DAMAGE OR PIN HOLES IN OUTER SHEATH.

52 WEEKS

5 LINK BOX INSPECTION

OFFLINE: LINK CONTACT RESISTANCE, VISUAL INSPECTION OF LINK BOX FOR MOISTURE INGRESS, CORROSION, ARCING TRACE ETC.

5 YEARS

6 EARTHING SYSTEM INSPECTION

ONLINE: MEASUREMENT OF SCREEN CURRENTS INSINGLE POLE EARTHING CABLES IN TERMINATIONSAIS/GIS

OFFLINE: BONDING INSPECTION, OVER SHEATH TEST, SVL TEST, MEASUREMENT OF EARTHING RESISTANCE, CONTINUITY TEST IN EARTHING CABLES

3 MONTHS

5 YEARS

7 PD BOX INSPECTIONOFFLINE: INSPECTION OF PD BOX FOR MOISTURE INGRESS, CORROSION, ARCING TRACE ETC.

5 YEARS

8SHEATH VOLTAGE LIMITER(SVL) PERFORMANCE CHECK

OFFLINE: VISUAL INSPECTION 5 YEARS

9CORONA MEASUREMENT ON OUTDOOR TERMINATION

ONLINE: TO DETECT INSULATION SYSTEM FOR OUTDOOR TERMINATIONS AND SURROUNDINGS WITH CORONA CAMERA

26 WEEKS

10HARMONIC CURRENT MEASUREMENT

ONLINE: MEASUREMENT OF HARMONIC CURRENT WITH POWER ANALYSER

52 WEEKS

14

MAINTENANCE PROCEDURES LAID FOR RELIABLE OPERATION.:

11INSULATION RESISTANCE OF OUTER SHEATH

OFFLINE: IR VALUE OF SHEATH TO BE MEASURED USING DC VOLTAGE TEST.THIS IS TO BE DONE ALONG WITH OFFLINE HIGH VOLTAGE TESTING AND PD MEASUREMENT.

5 YEARS

12 HIGH VOLTAGE TESTINGOFFLINE: HIGH VOLTAGE TESTING TO BE CARRIED OUT BY USING EXTERNAL VOLTAGE SOURCE MEGGER DAC 300

5 YEARS

13INSPECTION OF CONNECTION POINT

OFFLINE: INSPECTION OF CONNECTION POINT FOR AIS TERMINATIONS TO BE CARRIED OUT FOR IDENTIFYING OVERHEATING OR CORROSION ON CONNECTION POINT OF CABLES.

5 YEARS

15

MAINTENANCE PROCEDURES LAID FOR RELIABLE OPERATION.: