There is not any technical name for the transformer oil,
its only the specification which made the crude oil to
transformer oil(insulating oil). Nepthanic oil, Peraphenic
oil, Mineral Oil (its the specification which process the
crude oil to the nepthane base for the cooling of
transformer which have various acceptance norms as
specified in IS:335 below
Sl No. Characteristics Requirement Method of test as
per latest revision of IS as indicated below
1. Appearance The oil shall be clear and
transparent and free from suspended matters/sediments A
representative sample of oil shall be examined in a 100 mm
thick layer at the ambient temperature
2. Density at 29.5 Deg. C. Max. 0.89 g/cm3
Kinematic Viscosity at 27oC Max. 27 cst
4. Interfacial tension at 27oC Min. 0.04 N/m
5. Flash point Pensky Marten (closed),Min.
6. Pour point Max. -6 deg. C IS:1448[P:10]
7. Neutralisation value (Total acidity) Max.
0.03 mg KOH/G IS:1448 [P:2]
8. Corrosive Sulphur Non-corrosive IS:335
9. Electric Strength (breakdown voltage)
a) New unfiltered oil, Min. 30 kV (rms)
b) After filtration, Min. 60 kV (rms)
10. Dielectric dissipation factor (Tan delta) at 90º C,
max. 0.002 IS:6262
11. Specific resistance (resistivity)
a) at 90oC min. 150x1012 ohm-cm *
b) at 27oC min. 2500x1012 ohm-cm *
12. Oxidation stability IS:335
a) Neutralisation value after oxidation Max.
0.40 mg KOH/g
b) Total sludge value after oxidation Max.
0.10 percent by weight.
13. Presence of oxidation inhibitor present by weight
The oil shall not contain anti-oxidant additives
14. Water content maximum 50 ppm IS:13567
15. Aging characteristics after accelerated ageing
(open beaker method with copper catalyst)
a) Specific resistance (resistivity) Min.
1) at 27oC, Min. 4.5x1012 ohm-cm
2) at 90oC, Min. 0.2x1012 ohm-cm
b)Dielectric dissipation factor (Tan delta) at 90oC
c) Total acidity, Max. 0.05 mg KOH/gm IS:1448
d) Total sludge, Max. 0.05 percent by weight
Annex A of IS 12177
16. SK value, max. 4-8% volume increase IS : 335
Transformer oil, or insulating oil, is usually a highly-
refined mineral oil that is stable at high temperatures and
has excellent electrical insulating properties.
It is used in oil-filled transformers, some types of high
voltage capacitors, fluorescent lamp ballasts, and some
types of high voltage switches and circuit breakers. Its
functions are to insulate, suppress corona and arcing, and
to serve as a coolant.
TRANSFORMER OIL NAME
TECHINICAL NAME IS CRUDE OIL' BUT
ACCORDING TO BOSS LUBRICANT' CANADA
THE CHEMICAL NAME OF THIS OIL IS
SEVERELY HYDROTREATED HEAVY NAPHTHNIC DISTILLATE(SHHNH)......
A three phase load, around 4 km away from the 11/0.433KV
distribution transformer (Neutral of Transformer is
solidily earthed) and consisting of mainly very costly and
sensitive electronic equipments is giving trouble due to
high voltage difference between neutral and body earth.
Whether this problem can addressed by connecting neutral at
the load point solidly to earth?
1. which type of transformer connection is preferred in
case of power supply transformers?
(D) Zig Zag/Star
2. In a power transformer usuall which winding is closer to
(A) Primary winding
(B) Secondary winding
(C) Low Voltage winding
(D) High Voltage winding
3. The power factor of a purely inductive load is