IEC 60076-22-2-2019 pdf download.Power transformers — Part 22-2: Power transformer and reactor fittings — Removable radiators
Transformateurs de puissance — Partie 22-2: Accessoires pour transformateurs de puissance et bobines d’inductance — Radiateurs détachables.
The cooling capacity of a radiator depends on the average oil temperature rise and the height of the elements. This value shall be corrected by the coefficients K4V, KP and K1)If.
These diagrams are applicable for ONAN applications only. For ONAF, OFAN or OFAF applications, they have to be adjusted by multiplicative factors, peculiar to every configuration.
6.2.1.2 Type test conditions
The heat dissipation tests shall be performed in a closed and stable environment, within a suitable area, which maintains the ambient temperature stable without variation due to the thermic test itself or to the external climate conditions. This ambient temperature shall be maintained at around 25°C ± 5°C.
The ratio between the volume of the hot oil used in the cooling test and the volume of the room where the tests are performed shall be higher than 1:100.
The specific dissipation curves shall be obtained by testing several times the cooling performances of a specific radiator filled with transformer mineral oil and attached in its normal vertical position to a tank with a well-known oil capacity, dimensions and heat dissipation. The tank shall be designed in such a way that its heat dissipation capacity does not influence the dissipation characteristics of the radiator (see 6.2.1.5).
The radiator painting thickness shall be 120 lim ± 10 %.
The radiators tested shall be of the FG type. The dissipation characteristics of the FR type radiators shall be calculated by interpolation.
No other tests conditions are admissible.
6.2.1.3 Values and parameters to be measured
During the test, the following parameters shall be measured:
• ambient temperature (Tamb] defined as the average of three air temperatures measured by thermocouples immersed in oil and placed in the position described in Figure 5 at 2 m from the ground, with at least 2 m of free space around them:
• cooling capacity of the tank (q]: the heat dissipated by the tank only, without any radiator attached:
• radiator cooling capacity Eqradl = LqT0T] – LqtI expressed in kW.
All the values listed above shall be measured in the test conditions described in 6.2.1.2.
6.2.1.4 Instrument characteristics and requirements
The data collection system shall be based on the following elements:
• automatic temperature data collection system;
• thermocouple with functioning range -10 °C to +300 °C:
• monitoring system of the electric power of the oil immersed resistance.
The temperature data collection system shall have a minimum resolution of 0,1 C, and accuracy of ±1,5 %.
The only admitted heat source are batches of electric resistance immersed in oil with a regulation system of the input power which allows a continuous regulation.
All instruments shall be calibrated and certified.
6.2.1.5 CharacterIstics of the tank used for dissipation tests
The tank shall be equipped with a conservator to compensate the oil expansion. The shape of the tank shall be such as to guarantee a uniform temperature distribution in any area. A cylindrical shape is the preferred solution.
The tank shall be large enough to ensure a minimum ratio of 1:10 between the oil volume of the tank and the biggest radiator and high enough to allow the mounting of the biggest radiator on test.
To ensure a good temperature distribution inside the tank, a study of the temperature shall be performed during the heat test of the tank alone.
The resistor inside the tank shall have an adjustable position making it possible to change the DII parameter.
The tank shall be insulated to provide an emission of maximum 1 Wm2K1. The conservator does not require to be insulated. Figure 5 shows a typical test layout.IEC 60076-22-2-2019 pdf download.Power transformer and reactor fittings — Removable radiators