NF C52-062 Septembre 1993
Traversées à répartition capacitive immergées d'extérieur, 52 à 420 kV pour transformateurs ou bobines d'inductance immergés dans l'huile
La présente norme concerne les traversées à répartition capacitive immergées d'extérieur, de tension assignée 52 à 420 kV, destinées à des transformateurs ou bobines d'inductance immergés dans l'huile : à partie intérieure courte, avec isolation solide (papier enduit ou imprégné de résine synthétique), à partie intérieure courte, avec isolation en papier imprégné d'huile, à partie intérieure longue, avec isolation solide, à partie intérieure longue, avec isolation en papier imprégné d'huile.
https://www.boutique.afnor.org/norme/nf-c52-062/traversees-a...

NF C52-062:1993-09-01: Outdoor immersed capacitance graded bushings, 52 to 420 kV for oil immersed type transformers or reactors.
German title: KAPAZITIV GESTEUERTE FREILUFT-KESSEL-DURCHFÜHRUNG, 52 BIS 420 KV FÜR ÖLTRANSFORMATOREN ODER -DROSSELN.
https://www.beuth.de/en/standard/nf-c52-062/12371980

Traversées à répartition capacitive immergées d'extérieur, 52 kV à 420 kV pour transformateurs immergés dans l'huile
:
The purpose of this Technical Specification is to ensure the interchange ability between capacitance graded bushings, with comparable technical requirements, from different manufacturers.
:
Introduction 4
1 Scope 4
2 Normative references 4
3 Definitions 4
3.1 Draw-lead conductor 4
3.2 Solid rod conductor 4
3.3 Bottom terminal - current connection 5
4 Requirements 5
4.1 Application 5
4.2 Standard values of highest voltage for equipment (U ) 5
4.3 Standard values of rated current (I ) 5
4.4 Compliance 5
4.4.1 Test tap 5
4.4.2 Creepage distance 5
4.4.3 Insulating level 5
4.4.4 Operating conditions, test requirements 5
4.5 Additional requirements 5
4.6 Designation 6
4.6.1 Electrical design of oil end 6
4.6.2 Conductor principles and mechanical design of oil end 6
4.6.3 Conductor arrangement 6
4.6.4 Complete bushing designation 7
4.7 Design details 8
Annex A (informative) Example of bushing documentation 17
Figure 1 – Bushing dimensions (general) 8
Figure 2 – Bushing oil end dimensions 9
Figure 3 – Examples of current leader principles and mechanical design of oil end 10
https://standards.iteh.ai/catalog/standards/clc/79dda98e-32b...
(Unfortunately the text ends with par. 4.4.4.

Fig. 1 shows an example of a completely immersed bushing of this kind. Transformer bushings where only the bottom end enters the oil are better from the thermal aspect. If this section is made short and steps are taken to prevent the heat from traveling

Fig. 1. 420-kV resin-bonded paper bushing with short conical ends immersed entirely in oil (for transformers with cable boxes).
:
Concerning the short oil ends, it is true to say that in an oil-impregnated paper bushing the edges of the condenser layers are already in contact with oil and therefore offer the same advantages as the conical ends of a resin-bonded paper bushing. However, the difficulties lie in finding a short end porcelain which will hold along its surfaces in oil the breakdown voltages indicated in curve 2 of Fig. 2.
:
Fig. 4 shows a transformer bushing for a system voltage of 1050 kV which, in addition to withstanding the power-frequency voltage of 1200 kV (rms, 1 minute), was also subjected to full-wave standard impulses of 3050 kV and to chopped waves of 3500 kV.

Fig. 4. Transformer bushing for 1050-kV systems. Multicore resin-paper body with short conical lower end.
https://fdocuments.in/document/resin-bonded-paper-bushings-f...