Friday, April 15, 2011

Standard requirements for Insulating Oil

Equipment Voltage
Permissible Limits
Dielectric Strength
145 kV and above
30 kV (Min)
Break down voltage
Below 72.5 kV
40 kV (Min)
72.5kV and <145kV
50 kV (Min)
Water content
Below 145 kV
35 ppm (Max)
145 kV and above
25 ppm (Max)
Specific resistance
(Ohm-cm) at 90 deg C
All voltages
0.1 x1012 ohm-cm (Min)
Dielectric dissipation factor (tan d) at 90°C
All voltages
0.005 (Max:)
Neutralisation value (Total acidity)
All voltages
0.4 mg KOH/g (Max)
Interfacial tension at 27 deg C
All voltages
0.018 N/M (Min)
Flash point
All voltages
Max -15 °C
decrease of initial value
Sediment or precipitable sludge
All voltages
No sediment or precipitable sludge should be detectable
Dissolved gas analysis
145 kV and above
Refer IS 10593-1993 & DGA study chart

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