IEC 60076-22-4-2019 pdf download.Power transformers — Part 22-4: Power transformer and reactor fittings — Insulating liquid to water heat exchangers
Transformateurs de puissance — Partie 22-4: Accessoires pour transformateurs de puissance et bobines dinductance — Hydroréfrigérants.
4.4.1 External (atmosphere)
The materials used for the construction of the equipment or the surface treatment shall be resistant to accidental contact with the insulating liquid and suitable to withstand the environmental conditions given in 4.1. The corrosion protection shall be agreed between purchaser and manufacturer according to ISO 12944 (all parts). The responsibility to specify the correct level of corrosion protection lies with the purchaser and is dependent on the environment where the transformer will be located and on the durability required. Unless otherwise specified, minimum withstand level shall be C4 medium durability according to ISO 12944-6.
4.4.2 Insulating liquid side
In consideration of the storage conditions and expected time between shipment and commissioning, the corrosion protection on the insulating liquid side of the cooling system shall be agreed between purchaser and manufacturer. As a minimum requirement, precautions shall be taken to prevent the ingress of moisture and the development of internal corrosion. The internal flushing with insulation liquid fully miscible and compatible with the liquid to be used in service conditions and the use of blanking plates with gaskets are considered as a minimum. Internal painting, nitrogen filling, dehydrating material. etc.. can be used as other or additional solutions.
4.4.3 Water side
The corrosion protection on the water side of the cooling system shall be agreed between purchaser and manufacturer and is dependent on the water quality. To attain the requested degree of protection the manufacturer shall choose the combination of material and surface protection. As a minimum requirement for paint, an epoxy coating with a thickness of 150 pm shall be applied.
• The double tubes consist of two concentric tubes without a blocking fluid in between; the tubes are straight and the outer tubes are plain or finned. Between the inner and outer tube there shall be grooves, which enable the detection of a potential leakage by using a proper device. The double tubes are connected at both ends to the respective tube sheets by roll expansion or welding, The connection shall be fluid tight.
• The tube bundle can be arranged in different even number of passes to optimize water flow.
Removable tube bundles are the preferred solution for maintenance purposes.
5.2.4 Headers
• Two headers close the shell at both ends.
• One header includes flanged nozzles for the connection to the water piping. Inside the other header, the water is redirected.
5.3 General characteristics
5.3.1 Rating plate information
The rating plate shall be corrosion resistant and acid proof. It shall be visible when the heat
exchanger is assembled to the transformer and carry the following data:
• logo or name of manufacturer;
• country and manufacturing location;
• number of this document;
• manufacturer identification;
• manufacturer serial number;
• year of manufacturing.
Rated data:
• rated cooling capacity (kWj;
• rated liquid and water flow quantity [m3/h];
• inlet and outlet temperatures liquid-side and water-side (C1;
• pressure drop in the heat exchanger liquid side/water side [ban;
• maximum pressure in service for liquid-side [kPaJ;
• maximum pressure in service for water-side [kPaJ;
• maximum design temperature for liquid-side (°C];
• mass of heat exchanger without oil and water (kg];IEC 60076-22-4-2019 pdf download.Power transformer and reactor fittings — Insulating liquid to water heat exchangers