IEEE Std C57.19.04:2018 pdf download.IEEE Standard for Performance Characteristics and Dimensions for High Current Power Transformer Bushings with Rated Continuous Current in Excess of 5000 A in Bus Enclosures.
IEEE Std C57.19.04 covers the electrical, dimensional, and related special requirements for high current rating power transformer bushings located within bus enclosures that have rated continuous current in excess of 5000 A. Bushings covered by this standard are intended for use as components of liquid-filled transformers including, but not limited to, generator step-up (GSU) transformers.
2. Normative references
The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.
IEEE Std C37.23, IEEE Standard for Metal-Enclosed Bus.
IEEE Std C57.19.O0, IEEE Standard General Requirements and Test Procedure for Outdoor Power
Apparatus Bushings.
IEEE Std C57. 19.01 TM, IEEE Standard Performance Characteristics and Dimensions for Outdoor Apparatus Bushings.
IEEE Std C57.19.lOWM, IEEE Guide forApplication ofPowerApparatus Bushings.
At the time of publication of this standard, there were no equivalent dimensional standards in IEC 60137, Standard for Insulating Bushings for Alternating Voltages Above 1000 V.
3. Rated continuous current
The rated continuous current is the rrns current at rated frequency that a bushing shall be required to carry continuously under specified conditions without exceeding the permissible temperature limitations when tested tinder the conditions specified below.
3.1 Thermal basis of rating
Bushings applied per this standard are subject to specific thermal conditions. These conditions include the increase for allowable temperature rise for bus connected to the air end of the bushing and the hot enclosed space around the air end of the bushing. The allowable bus rise is 65 K, per Table 5 in IEEE Std C37.23-20 15, and the allowable air space rise is 40 K. These are over a 30°C average ambient resulting in a bus temperature of 95 °C average (max. 105 °C) and an enclosed average air temperature of 70 °C (max. 80 °C). The thermal testing below takes into account these elevated thermal conditions for bushings installed in this environment.
It shall be noted that the thermal rating of the materials used for various bushing designs cannot bc used as an indicator of how a bushing will perfonn in operation or as a method to compare bushing designs. It is the responsibility of the manufacturer to use the appropriate materials to meet the resulting temperatures generated within the bushing. The use of materials with higher thermal index ratings does not alone indicate greater thermal margin or higher overload capabilities.
3.2 Requirement for thermal testing
Each bushing design shall be tested for thermal performance per the requirements of 3.3. unless it can be shown analytically to be identical to or superior in thermal performance to a similarly designed bushing already shown by testing to meet the requirements of this standard. Specifically, if a previously tested reference bushing can verify that a specific analytical technique provides accurate results, that same analysis may be used to thermally evaluate bushings that have the same materials and very similar design in lieu of testing, as long as the bushing being evaluated has a current rating between 80% and 120% of the reference bushing. A bushing ofTered for sale prior to the release of this standard may be thermally qualified by analytical evaluation, which indicates it meets the intent of this standard based on testing performed per 7.2.3 of IEEE Std C57. 19.00-2004 on the same bushing design. The analysis method is at the discretion of the bushing manufacturer, but is subject to the user’s approval.IEEE Std C57.19.04 pdf download.