IEEE 95-2002 pdf download lEEE Recommended Practice for Insulation Testing of AC Electric Machinery (2300 V and Above) With High Direct Voltage
3.Definitions
3.1 absorption (polarization) current (i ): Current that results from polarized atoms and moleculesbecoming displaced and algned when a dielectric is placed in an electric field. Upon application of a voltagcstep, the absorption current decays from a comparatively high initial value to nearly zero. The initial magni.tude and rate of decay depend on the type, condition, dimensions, and temperature of the insulation.
3.2 absorption coeficient (K): The absorption current measured 1 minute after the application of a constantelectric stress, divided by the applied voltage and the geometric capacitance.
3.3 absorption exponent (n): The exponent of the time in minutes that defines the rate of decay of theabsorption current following the application of a constant electric stress.
3.4 absorption ratio (N): The ratio of the absorption current after 1 minute divided by the absorption current after 10 minutes where the times are measured from the application of the constant electric stress. Thebase 10 logarithm of the absorption ratio N is equal to the absorption exponent n.
3.5 acceptance proof test: A pass/fail type of test made on a new or repaired winding before allowing themachine to be placed in service. The test may be performed at the factory, after field installation, or both (secANSI C50.10-1990)
3.6 breakdown current (ig): The current discharged as a result of insulation failure. The peak value of thiscurrent may be very high, reflecting the energy stored in the capacitance of the winding. Normally, this cur-rent cannot be accurately measured.
3.7 breakdown voltage: The voltage at which a disruptive discharge takes place through the volume or overthe surface of the insulation.
3.8 conduction (leakage) current (c): The sum of the volume conduction current and the surface conduc.
tion current.
3.9 controlled overvoltage test (eg, stepped or ram ped voltage tests): A test in which the magnitude ofthe applied direct voltage is manually or automatically increased above the peak value of the nom inal line.to-ground rms rating of the insulation system. During such tests, measured current is continuouslymonitored for indications of insulation defects or deterioration. If insulation failure appears imminent, anattempt may be made to stop the test before damage due to breakdown occurs.
3.10 electric strength (dielectric strength): The maximum applied voltage an insulation system can with.
stand without failure.
3.11 electroendosmosis: The migration of moisture within a stationary solid material, under the influence ofan applied electric field, toward an electrode. The net movement of water molecules is generally toward thenegatively-charged electrode
3.12 geometric capacitance: The capacitance of a geometric arrangement of the electrodes where the effectof the relative dielectric constant of the insulation system has been included The capacitance value mea-sured at 50 Hz or 60 Hz is sufficiently accurate for use in connection with direct-current measuremients[B29].
3.13 geometric capacitive current (ic): A reversible component of measured current that is equal to the rateof change of applied oltage times the winding-to-ground geometric capacitance. Following an applied
IEEE 95-2002 pdf download
PS:Thank you for your support!
