The rated current of Electrical Equipment is at reference ambient temperature and under rated voltage working conditions,heating does not exceed the maximum current allowed to pass when heating for a long time.The ambient temperature has a great influence on the maximum current allowed to pass for a long time. Due to the installation location of the equipment and the reference ambient temperature is not necessarily the same, it is generally specified:
When electrical equipment is working at an ambient temperature higher than 40℃ (but not higher than +60℃), it is recommended to reduce the rated current by 1.8% for each increase in the ambient temperature by 1℃ ;When it is lower than 40℃, it is recommended that the rated current increase by 0.5% for every 1℃ decrease in the ambient temperature, but the maximum should not exceed 20% of the rated current.
It is the operating current value of the air switch or contactor over-current protection device. This value should be adjusted to ensure that it trips during over-current. It cannot be small or large. If it is small or large, it will malfunction. The adjustment is called setting .