RIP vs OIP

Omicron Workshop – Diagnosemessungen an Leistungstransformatoren

Definitions Dielectric Losses are caused by: • Conductive losses

2.50E-03

• Polarization losses

2.00E-03

Serial Parallel Sum

1.50E-03

• Partial discharges

1.00E-03 5.00E-04 0.00E+00 0

Assessment of the Condition of High Voltage Bushings

50

Parallel circuit

|I | 1 DF : tan δ = RP = | I CP | R P ⋅ ω ⋅ C P PF : cos ϕ =

150

200

250

300

350

400

Serial circuit

CP

| I RP | | I tot |

100

RP

DF : tan δ =

UR = RS ⋅ ω ⋅ C S UC

PF : cos ϕ =

UR U tot

RS CS PAGE 4

Capacitance Values

Power (Dissipation) Factor

• Bushings: •Bushings:

• Partial breakdowns between layers

• Aging and decomposition of insulation

• Incoming oil into cracks of solid insulation (RBP)

• Water content

• Between transformer windings:

• Bad contacted electrodes or capacitive layers

• Change of the geometry between winding

• Cracks in the insulation

• Between windings and tank

• (Partial) discharges

• Displacement of the active part within the tank

• Between windings and core

• Transformers:

• Displacement of the winding or the core (if the core

• Aging

ground can be disconnected)

• Water content in the oil and in the paper

• Core to tank

• Contamination by particles

• Movement of the core (if the core ground can be disconnected)

PAGE 5

PAGE 6

Limits

Condenser Type Bushings

Typ Insulation

RIP

OIP

RBP

Gas

Resin impregnated paper

Oil impregnated paper

Resin bonded paper

SF6 or other gases

< < 0,7% 0.7%*

< < 0,7% 0.7%*