The temperature of the specimens shall be stabilized at 25 °C ± 3 K (the definition oftemperature stability is given in IEC 60068-1 and IEC 60068-5-2). This shall be achieved byeithera) placing the specimens in a separate chamber before introducing it into the test chamber,or,b) adjusting the temperature of the test chamber to 25 °C ± 3 K after the introduction of thespecimens and maintaining them at this level until the specimens attain temperaturestability.During the stabilization of temperature by either method, the relative humidity shall be withinthe limits prescribed for standard atmospheric conditions for testing.Following stabilization, with the specimens in the test chamber, the relative humidity shall beincreased to not less than 95 % RH at an ambient temperature of 25 °C ± 3 K.7.3 Description of the 24 h cycle7.3.1 The temperature of the chamber shall be raised to the appropriate upper temperatureprescribed by the relevant specification. The upper temperature shall be achieved in a period of3 h ± 30 min and at a rate within the limits defined by the shaded areas in Figures 2a and 2b.During this period, the relative humidity shall not be less than 95 % RH. During the last 15 minit shall not be less than 90 % RH.7.3.2 The temperature shall then be maintained within the prescribed limits for the uppertemperature (±2 K) until 12 h ± 30 min from the start of the cycle.During this period, the relative humidity shall be 93 % RH ± 3 %RH. During the first and last15 min it shall be between 90 % RH and 100 % RH.7.3.3 The temperature shall then be lowered in accordance with one of the two variants givenbelow.The temperature shall be lowered to 25 °C ± 3 K within 3 h to 6 h. The rate of fall for the firstone and one half hours shall be such that, if maintained as indicated in Figure 2a, it wouldresult in a temperature of 25 °C ±3 K being attained in 3 h ± 15 min. The relative humidity shallbe not less than 95 % RH. During the first 15 min it shall be not less than 90 % RH.7.3.4 The temperature shall then be maintained at 25 °C ± 3 K with a relative humidity of notless than 95 % RH until the 24 h cycle is completed