AS 4388-1996

1 - AS 4388-1996 A METHOD OF TEMPERATURE-RISE ASSESSMENT BY EXTRAPOLATION FOR PARTIALLY TYPE-TESTED ASSEMBLIES (PTTA) OF...
4 - PREFACE
5 - CONTENTS
7 - 1. Introduction
7 - 2. Scope
7 - 3. Object
7 - 4. Conditions for application
8 - 5. Calculation
8 - 5.1 Necessary information
8 - 5.2 Calculation procedure
8 - 5.2.1 Determination of the effective cooling surface Ae of the enclosure
9 - 5.2.2 Determination of the internal temperature rise delta t 0.5 of the air at mid-height of the enclosure
9 - 5.2.3 Determination of the internal temperature rise delta t 1.0 of air at the top of the enclosure
9 - 5.2.4 Characteristic curve for temperature rise of air inside enclosure
11 - 6. Evaluation of the design
22 - APPENDIX A - EXAMPLES FOR THE CALCULATION OF THE TEMPERATURE RISE OF AIR INSIDE ENCLOSURES
29 - Amendment 1

Provides a method to determine the temperature rise inside a low-voltage switchgear and controlgear assembly by extrapolation from data found by tests on other assemblies. This Standard is identical with and has been reproduced from IEC 890:1987, including the Corrigendum:1988 and Amendment 1:1995.

The following method is applicable to enclosed PTTA or partitioned sections of PTTA without forced ventilation.Notes1. - The influence of the materials and wall thicknesses usually used for enclosures are negligible on the steady state temperatures. The method is therefore applicable to enclosures made of sheet steel, sheet aluminium, cast iron, insulating material and the like.2. - For open-type and dead-front PTTA, no temperature-rise assessment is needed if it is obvious that no excessive air temperatures are likely to arise.

First published as AS 4388-1996.