AS NZS IEC 60947.7.3-2015 pdf free download – Low-voltage switchgear and controlgear Part 1: General rules.
The lower limit of the ambient air temperature is -5 ‘c.
Ambient air temperature is that existing in the vicinity of the equipment if supplied withoutenclosure, or in the vicinity of the enclosure if supplied with an enclosure,
NOTE 1 Equipment intended to be used in ambient air temperature above +40 “C(e.g. in forges, boiler rooms,tropical countries) or below -5 C(e.g.-25 “C, as required by IEC-60439-161439 series for outdoor installed lowvoltage switchgear and controlgear assemblis) should be designed or used according to the relevant productstandard, where applicable，or according to agreement between manufacturer and user. Information given in themanufacturer’s catalogue may take the place of such an agreement.
NOTE 2 Ambient air temperature(s) for certain types of equipment, e.g. circuit-breakers or overload relays forstarters,is indicated in the relevant product standard.
6.1.2Altitude
The altitude of the site of installation does not exceed 2 000 m.
NOTE For equipment to be used at higher altitudes,it is necessary to take into account the reduction of thedielectric strength and the cooling effect of the air. Electrical equipment intended to operate under these conditionsshall be designed or used in accordance with an agreement between manufacturer and user,
6.1.3Atmospheric conditions
6.1.3.1 Humidity
The relative humidity of the air does not exceed 50 % at a maximum temperature of +40°℃.Higher relative humidities may be permitted at lower temperatures， e.g.90 % at +20 °c.Special measures may be necessary in cases of occasional condensation due to variations intemperature.
NOTE Pollution degrees, as stated in 6.1.3.2,define the environmental conditions more precisely,6.1.3.2Pollution degree
The pollution degree (see 2.5.58) refers to the environmental conditions for which theequipment is intended.
NOTE 1 The micro-environment of the creepage distance or clearance and not the environment of the equipment
the equipment. lt includesall factors influencing the insulation， such as climatic and electromagnetic conditions.determines the effect on the insulation.The micro-environment might be better or worse than the environment ofgeneration of pollution. etc.
For equipment intended for use within an enclosure or provided with an integral enclosure, thepollution degree of the environment in the enclosure is applicable.
For the purpose of evaluating clearances and creepage distances, the following four degrees ofpollution of the micro-environment are established (clearances and creepage distancesaccording to the different pollution degrees are given in Tables 13 and 15):
Pollution degree 1:
No pollution or only dry,non-conductive pollution occurs.Pollution degree 2:
Normally,only non-conductive pollution occurs.Occasionally，however，a temporary conduc-tivity caused by condensation may be expected.
Pollution degree 3:
Conductive pollution occurs, or dry, non-conductive pollution occurs which becomes conductivedue to condensation.
Pollution degree 4;
The pollution generates persistent conductivity caused, for instance, by conductive dust or byrain or snow.
Standard pollution degree of industrial applications:
Unless otherwise stated by the relevant product standard, equipment for industrial applicationsis generally for use in pollution degree 3 environment. However, other pollution degrees may beconsidered to apply depending upon particular applications or the micro-environment.
NOTE 2 The pollution degree of the micro-environment for the equipment may be influenced by installation in anenclosure.
Standard pollution degree of household and similar applications:
Unless otherwise stated by the relevant product standard, equipment for household and similarapplications is generally for use in pollution degree 2 environment.
6.1.4Shock and vibration
Standard conditions of shock and vibration to which the equipment can be submitted are underconsideration.
6.2Conditions during transport and storage
A special agreement shall be made between user and manufacturer if the conditions duringtransport and storage,e.g. temperature and humidity, differ from those defined in 6.1, exceptthat,unless otherwise specified,the following temperature range applies during transport andstorage: between -25 °C and +55°C and, for short periods not exceeding 24 h, up to +70 °℃.AS NZS IEC 60947.7.3 pdf download.