IEEE 21:1976 pdf download.IEEE Standard General Requirements and Test P rocedure for Outdoor Apparatus Bushings.
IEEE 21 applies to outdoor power class apparatus bushings which have basic impulse insulation levels of 110 kV and above for use as components of oil-filled transformers, oil-filled reactors, and oil circuit breakers.
This standard does not apply to the following:
(1) i-ugh-voltage-cable terminations (potheads)
(2) Bushings for instrument transformers
(3) Bushings for test transformers
(4) Bushings in which the major insulation is provided by a gas
(5) Bushings applied with gaseous insulation (other than air at atmospheric pressure) external to the bushing
(6) Bushings for distribution class circuit breakers and transformers
(7) Bushings for automatic circuit reclosers and line sectionalizers
(8) Bushings for oil-less and oil-poor apparatus
1.2 Purpose. This standard defines the special
terms used, service conditions, rating, general requirements, and test procedure. See IEEE Std 24-1976, Electrical, Dimensional, and Related Requirements for Outdoor Apparatus Bushings (ANSI C76.2-1976), for specific list. ings of values of electrical and mechanical characteristics, dimensions, and other related test and quality control requirements which are described in this standard.
2. Referenced Documents
The following standards form a part of this standard to the extent specified herein.
Institute of Electrical and Electronics Engineers (IEEE)
IEEE Std 100-1972, Dictionary of Electrical and Electronics Terms (ANSI C42.100-1972)
IEEE Std 4-1969, Techniques for Dielectric Tests (ANSI C681-1968 (R1973)J
IEEE SkI 332-1972, Techniques for Switching Impulse Testing (ANSI C68.2-1972)
IEEE Std 24.1976, Electrical, Dimensional, and Related Requirements for Outdoor Apparatus Bushings (ANSI C76.2- 1976)
When the preceding standards are superseded by a revision approved by the IEEE, the revision shall apply.
National Electrical Manufacturers Association(NEMA)
Publication 107-1964 (R1971), Methods of Measurement of Radio Influence Voltage of High Voltage Apparatus
3. Definitions
For terms not specifically defined in this standard see IEEE Std 1001972, Standard Dictionary of Electrical and Electronics Terms(ANSI C42.100-1972).
ambient temperature. The temperature of the surrounding air that comes in contact with the device or equipment in which the bushing is mounted.
basic impulse insulation level (BIL). A reference insulation level expressed as the impulse crest voltage of the 1.2 X 50 ps wave which the bushing will withstand when tested in accordance with specified conditions.mounting on a barrier, conducting or otherwise, for the purpose of insulating the conductor from the barrier and conducting current from one side of the barrier to the other.
bushirg potential tap. An insulated connection to one of the conducting layers of a bushing providing a capacitance voltage divider to indicate the voltage applied to the bushing.
bushing test tap. An insulated connection to one of the conducting layers of a bushing for the purpose of making insulation power factor tests.
capacitance (of bushing). (1) The main capacitance, C1, of a condenser bushing is the value in picofarads between the high-voltage conductor and the potential tap or the test tap. IEEE 21 pdf download.