Drying Out Process For Transformer

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3. Transformer without Dry air or Nitrogen 4. Open transformer more than 48 hours

1. Through Filter Machine & Vacuum 2. Circulating Hot Air

3. Through Short Circuit Heating Process

4. Cycle of Heating (through oil) – Vacuuming – N2 filling

PROCESS STEPS

FILTER MACHINE & VACUUM

Condition Tank should be empty 1 except active part Condition Radiators & PRV , 2 Conservator must be separated Condition X’mer is in CLOSED 3 condition Step - 1

a) Arrange Pipe on top side core with plenty of holes surrounding pipe or else b) Fill complete oil and circulate

CIRCULATING HOT AIR SHORT CIRCUIT HEATING PROCESS

CYCLE OF HEATING – VACUUMING – N2 FILLING

Tank should be empty except active part Radiators & PRV , Conservator must be separated Top side OPEN condition (as per the steps only) ARRANGE a) Hot Air b) Electric X’mer dryer c) Baffle to catching inflammabl e particles came from Heater

Complete X’mer oil filled

Tank should be empty except active part

Radiators & PRV , Conservator must be separated CLOSED condition

Radiators & PRV , Conservator must be separated CLOSED condition

a) Short the low voltage winding b) Apply reduce voltage on HV side

2

a) Vacuum drawn from the top valve (depends on permissible value )

REMARK

Step – 2

a) Spray Hot oil through top pipe on the active part b) After getting temperatur e vacuum from the top cover(apply permissible vacuum)

Spep – 3

a) Check IR value at regular Interval and compare with BATH TUB b) Circulating till you received desire value

a) Hot air from external heaters is blown from bottom valve b) Same time open the top side for escape hot air c) Speed of air must not exceed 600 m /minute . a) The Temp. raised Gradually Temp. bet. 55 to 65 – 8 hour, 65 to 75 – 8 hur n so oon depends on IR value improveme nt (not 3

a) Voltage should be maintain up to the current in the winding does not exceed 70 % of full load current b) Maintain Oil temp. near to 75 deg. Cent.

a) X’mer core and coil heated externally by using of heater OR b) Circulate Oil 2 – 3 times and remove immediate and take vacuum c) Keep Vacuum pump on between 48 to 96 hours .

a) Winding temp should no case of exceed 90 deg. b) Measured Due point if possible

a) Vacuum Broken with dry Nitrogen and kept 48 hours with positive pressure b) Measured dew point c) If still not achieved re process the same thing.

Note

Most Practical Method

more than 80 deg.cent) Good Results but Risky for site

Not so popular

4

The Most Effective & Quickest method. Provided Transformer Tank design Vacuum pressure