Oil Filled Distribution Transformer

CONTENTS

1.0. SCOPE

2.0 RESPONSIBILITY

3.0 SAFETY

4.0 OIL FILLED DISTRIBUTION TRANSFORMER

TOOLS / EQUIPMENTS

TEST EQUIPMQNTS

INSTALLATION PROCEDURE

INSPECTION & TESTING PROCEDURE

TOOLS / EQUIPMENTS

· Hand tools for Electricians

· Lifting crane

· Fork Lift

TEST EQUIPMENT

· Digital multimeter.

· Ductor Tester

· Clamp on Ammeter (Digital)

· High pot Tester Set (with all accessories)

· 1 KV Insulation Resistance Tests

· 5 KV Insulation Resistance Tests

· Secondary injection set

· Phase rotation meter.

All the testing instruments will have calibration certificate valid for minimum six months. Calibration certificate can be verified during testing.

INSTALLATION PROCEDURE

· The Distribution Transformer will be installed in place after completion of all civil work in Transformer Room i.e. Concrete plinth, Trenches, Fence, channels external wall etc…

· Installation of the transformer will be co-ordinated with the civil team

· Rails for transformer rollers will be installed

· The transformers will be unloaded directly onto position as per approved Layout drawings.

· Align and level the transformers.

· Fix the transformer on the rail as per manufacture recommendation.

· Gladding and proper termination for HV side.

· Gladding and proper termination for LV side and Control Cables

· Ground the transformer as per approved Earthling Layout

· Testing of the transformer as per Inspection and Testing procedure

· Termination of HV / LV Control and Instrument cables. Testing of HV cable shall be carried out after termination is installed and before the cable is finally bolted to the HV terminal of the transformer

· Installation shall be carried out fully complying with manufacturer’s recommendation and procedures.

· Installation check list will be submitted to Engineer for approval

· Tighten the bolts with torque wrench as per manufacturer recommendation

· Necessary site inspection requests shall be submitted to Engineer during the above activities at site.

· Maintenance procedure / Instructions shall be furnished to maintenance team / Engineer during delivery of materials at site.

INSPECTION OF TRANSFORMER

· Check Transformer for any Physical damage

· Check nameplate rating and tagging

· Check if installation is made as per approved drawing and in line with vendor recommendations

· Check Cable glanding and termination

· Check operation and condition of tapping switch

· Check Earthing

· Check Cable and Cable Tray supports

· Check protection devices i.e. winding temperature switch / thermometer

· Check door locks for HV and LV Terminal boxes

TESTING OF TRANSFORMER

The following Test of the Transformer will be carried out:

· Insulation Resistance winding LV side 1000V megger

· Megger of winding HV side 5000V megger

· Measurement of winding resistance LV and HV side by using High resistance ductor Test

· Measurement of impedance voltage on all tap’s

· Measurement of no load loss

· Measurement of load losses at principle tap and extremes

· Induced AC voltage withstand voltage test with measurement of partial discharge

· Separate source AC voltage withstand voltage test

· Measurement of Voltage ratio between primary and secondary winding

· Check operation of winding temperature switch / indicator

· Check vector group by voltmeter method

· Check phase sequence

· Check polarization index

· Applied over voltage test at 2000V, AC, 60 sec. on wiring and supervisory equipment

· Any other test as stated in ADDC Specs

All above Tests shall be recorded in Pre-commissioning Test forms