standards for switchyard.pdf

C HAPT ER 4

Standard acceptable technical values 1.1

Fresh Transformer oil before filling in Transformer Parameters Standard Values (Acceptable range) (a) Appearance Clear and transparent and free from suspended matter or sediments (b) Density at 29.50 C 0.89 g/cm3 (Max) 0 (c) Kinematic Viscosity at 27 C at 27 cSt (Max) under consideration 0 40 C, Max (d) Interfacial Tension (IFT) 270 C 0.04 N/m (Min) (e) Flash point, Pensky marten 140 0 C (Min) (Closed) (f) Pour point - 60 C (Max) (g) Acidity (Neutralisation Value) (i) Total acidity 0.03 mg KOH/ g (Max) (ii) Inorganic acidity/ alkalinity Nil (h) Corrosive Sulphur Non – Corrosive (i) Di-electric strength (Breakdown voltage) (i) New unfiltered oil 30 kV, rms (Min) (ii) After filtration 60 kV, rms (Min) (j) Dielectric Dissipation Factor (Tan 0.002 (Max) ) DDF at 900 C (k) Specific Resistance (Resistivity) (i) at 900 C 35*1012 Ω –cm (min) 0 (ii) at 27 C 1500*1012 Ω –cm (min) (l) Oxidation stability (i) Neutralization value after 0.40 mg KOH/g (Max) oxidation (ii) Total Sludge after Oxidation 0.10% by weight (Max) (m) Ageing Characteristics after Acceleration ageing (open breaker method with copper catalyst) (i) Specific Resistance (Resistivity) at 270 C 2.5*1012 Ω –cm (min) 0 at 90 C 0.2*1012 Ω –cm (min) (ii) Dielectric Dissipation Factor ( 0.2 (Max) Tan delta) at 900 C (iii) Total Acidity 0.05 mg KOH/ g (Max) (iv) Total Sludge 0.05% by weight (Max) (iv) Total Sulphur 0.15% (Max) (n) Water content of new unfiltered 50 ppm (Max) oil (o) S. K. Value 4 to 8% by mass (Max) (q) Presence of Oxidation Inhibitor Oil shall not contain antioxidant additives. Value of 0.05% by mass (Max) shall be treated as absence of

Source IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993

IS 335 – 1993 IS 335 – 1993 IS 335 – 1993

IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993

IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IS 335 – 1993 IEC 60296-2003 IS 335 – 1993 IEC – 60296, 2003 IS 335 – 1993

DBPC – Phenolic type inhibitor Not detectable 0.1 mg/kg (Max)

IEC – 60296, 2003

Not applicable 0.1 mg/kg (Max)

IS 335 – 1993 IEC – 60296, 2003

(u) Furfural (Aging criteria for oil immersed Power Transformer)

Warning Trouble 1.5 ppm 15 ppm

(v) Total Furan Content

250 parts per billion (ppb)

CIGRE DOC. No. 227 Life Management Technique for Power Transformer Page – 107 Transformer Diagnostic USBR, june 2003, Page 15

Additional Requirement for inhibited oil Inhibitor content (Antioxidation additive content) DBPC (Ditertiary Butyl Paracersol) DBP (Ditertiary Butly Phenol)

Minimum 0.08 % by mass and maximum 0.4% by mass

(r) PCB content (Polychlorinated Bipheyls) (s) Dissolved Gas Analysis (DGA) (t) 2 – furfural (Furan Analysis, Test method – IEC 61198:1993)

Minimum 0.15 % by mass and maximum 0.3% by mass

1.2

Inhibitor content determination ( Test Mehod:IS – 13631) IEC – 60296, 2003 Nynas and shell Inhibited oil

Transformer oil for in-service Transformer Oil Parameters (a) Appearance (b) Break Down Voltage (BDV) (GAP – 2.5 mm) min (c) Water content (Moisture) (Max) (d) Acidity (Neutralization value ( Max) (e) Sediment & Sludge (Max) (f) Resistivity (i) Resistivity at 200 C (Min) (ii) Resistivity at 900 C (Min) (g) Dielectric Dissipation factor at 900C and 40-60 Hz (Tan Delta/ power factor) (Max) (h) Inter Facial Tension (IFT) AT 270 C (Min) (i) Flash Point (Min)

At the time of first Charging. Clear, free from sediment and suspended matter 40 kV for < 72.5 kV 50 kV for 72.5 to 170 kV 60 kV for > 170 kV 20 ppm for < 72.5 kV 15 ppm for 72.5 to 170 kV 10 ppm for > 170 kV 0.03 mg KOH/g

During O&M Clear without visible contamination 30 kV for < 72.5 kV 40 kV for 72.5 to 170 kV 50 kV for > 170 kV No free moisture for 170 kV 0.3 mg KOH/g

0.01% by mass

0.02 by mass

IS 1866 - 2000

1*1012 Ohm-cm

IS 1866 - 2000

6*1012 Ohm-cm

0.1*1012 Ohm-cm

IS 1866 - 2000

0.015 for < 170 kV 0.01 for ε170 kV

1.0 for