Table I Recommended maintenace scheduld for transformers of capacities less than 1000KVA
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Sr No
|
Inspection Frequency
|
Items To Be Inspected
|
Inspection Notes
|
Actions Required If Inspection Shows Unsatisfactory Conditions
|
|
1
|
Load(KW)
|
Check against rated figures
|
-
|
|
|
Temperature
|
Oil Temp and ambient temp figures
|
-
|
||
|
Voltage
|
Check against rated figures
|
-
|
||
|
2
|
Daily
|
Dehydrating breather
|
Check that air-passage is clear Check colour of active agent
|
If silica gel is pink change by spare charge. The old chargemay be reactivated foruse again.
|
|
3
|
Monthly
|
Oil level in transformer
|
Check transformer oil level
|
If low, top-up with dry oil. Example
|
|
Connections
|
Check tightness
|
If loose, tighten
|
||
|
4
|
Quarterly
|
Bushings
|
Examine for cracks and dirt deposits
|
Clean and replace
|
|
5
|
Half yearly
|
Conservator Cable boxes, gasket joints and general paint work oil level connections
|
Check for moisture under cover Inspect
|
Improve ventilation, check oil
|
|
6
|
Yearly
|
Oil in transformer
|
Check for dielectric strength and water content. Check for acidity and sludge
|
Take suitable action in restore quality of oil
|
|
Earth resistance
|
-
|
Take suitable action if earth resistance is high
|
||
|
Relays alarm their circuits, etc.
|
Examine relay and alarm contacts, their operation, fuses, etc. Check relay accuracy, etc
|
Clean the components and replace contacts and fuses if necessary. Change the setting if necessary
|
||
|
7
|
2 yearly
|
Full transformer
|
Internal inspection above core
|
Filter oil regardless of condition.
|
|
8
|
5 yearly
|
-
|
Overall inspection including lifting of core and coils
|
Overall inspection including lifting of core and coils
|
Note: When inspection of core and coils are to be done, it is recommended the manufacturer be consulted Ideally it is good to take Megger& Magnetic balance once in 5 years.
