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PD IEC TR 60890:2022 A method of temperature-rise verification of low-voltage switchgear and controlgear assemblies by calculation, 2022
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- CONTENTS
- FOREWORD
- INTRODUCTION
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Verification conditions
- 5 Calculation method [Go to Page]
- 5.1 Assumptions made in this calculation
- 5.2 Necessary information
- 5.3 Calculation procedure [Go to Page]
- 5.3.1 General
- 5.3.2 Determination of the effective cooling surface Ae of the enclosure
- 5.3.3 Determination of the internal temperature-rise Δt0,5 of the air at mid-height of the enclosure
- 5.3.4 Determination of the internal temperature-rise Δt1,0 of air at the top of the enclosure
- 5.3.5 Characteristic curve for temperature-rise of air inside enclosure
- Figures [Go to Page]
- Figure 1 – Temperature-rise characteristic curve for enclosures with Ae exceeding 1,25 m2
- 5.4 Maximum internal air temperature limits
- 6 Further considerations [Go to Page]
- 6.1 General
- 6.2 Guidance on the effects of an uneven power distribution
- Figure 2 – Temperature-rise characteristic curve for enclosures with Ae not exceeding 1,25 m2
- 6.3 Guidance on the additional temperature-rise effect due to solar radiation
- 7 Evaluation of the design
- Tables [Go to Page]
- Table 1 – Method of calculation, application, formulas and characteristics
- Table 2 – Symbols, units and designations
- Table 3 – Surface factor b according to the type of installation
- Table 4 – Factor d for enclosures without ventilation openings and with an effective cooling surface Ae > 1,25 m2
- Table 5 – Factor d for enclosures with ventilation openings and an effective cooling surface Ae > 1,25 m2
- Figure 3 – Enclosure constant k for enclosures without ventilation openings, with an effective cooling surface Ae > 1,25 m2
- Table 6 – Equation for Figure 3
- Figure 4 – Temperature distribution factor c for enclosures without ventilation openings and with an effective cooling surface Ae > 1,25 m2
- Table 7 – Equations for Figure 4
- Figure 5 – Enclosure constant k for enclosures with ventilation openings and an effective cooling surface Ae > 1,25 m2
- Table 8 – Equations for Figure 5
- Figure 6 – Temperature distribution factor c for enclosures with ventilation openings and an effective cooling surface Ae > 1,25 m2
- Figure 7 – Enclosure constant k for enclosures without ventilation openings and with an effective cooling surface Ae ≤ 1,25 m2
- Table 9 – Equations for Figure 6
- Figure 8 – Temperature distribution factor c for enclosures without ventilation openings and with an effective cooling surface Ae ≤ 1,25 m2
- Table 10 – Equation for Figure 7
- Table 11 – Equation for Figure 8
- Figure 9 – Calculation of temperature-rise of air inside enclosures
- Annexes [Go to Page]
- Annex A (informative) Examples for the calculation of the temperature-rise of air inside enclosures [Go to Page]
- A.1 Example 1
- Figure A.1 – Example 1, calculation for an enclosure with exposed side faces without ventilation openings and without internal horizontal partitions
- Figure A.2 – Example 1, calculation for a single enclosure [Go to Page]
- A.2 Example 2
- Figure A.3 – Example 2, calculation for an enclosure for wall-mounting with ventilation openings
- Figure A.4 – Example 2, calculation for one enclosure half
- Figure A.5 – Example 2, calculation for an enclosure for wall-mounting with ventilation openings
- Annex B (informative) Guidance on the effects of an uneven power distribution [Go to Page]
- B.1 Horizontal partition
- B.2 Calculation of internal air temperature-rise for assemblies with ventilation openings with even power distribution and less than 50 % perforation in horizontal partitions
- Figure B.1 – Examples of assemblies with horizontal partitions [Go to Page]
- B.3 Calculation of internal air temperature-rise with an uneven power distribution
- Figure B.2 – Temperature-rise verification of a higher-power circuit
- Annex C (informative) Guidance on the additional temperature-rise effect due to solar radiation [Go to Page]
- C.1 General
- C.2 Solar radiation phenomena
- Figure C.1 – Solar radiation phenomena [Go to Page]
- C.3 Solar radiation – consequences for thermal calculation
- Figure C.2 – Interpolation curve
- Table C.1 – Approximate solar absorption radiation coefficients (according to colour) [Go to Page]
- C.4 Solar radiation of enclosures with air ventilation openings
- Annex D (informative) Guidance on the effect of different enclosure materials, construction and finishes [Go to Page]
- D.1 General
- D.2 Validity criteria
- D.3 Material of enclosure
- D.4 Results
- Figure D.1 – Results of comparison tests
- Annex E (informative) Guidance on the effects of different natural ventilation arrangements
- Figure E.1 – Examples of crossing diagonal installation
- Figure E.2 – Effect of additional filters
- Annex F (informative) Guidance on forced ventilation management [Go to Page]
- F.1 General
- F.2 Forced ventilation installation system
- F.3 Installation considerations
- Figure F.1 – Examples of forced ventilation arrangements
- Annex G (informative) Power loss values calculation [Go to Page]
- G.1 General
- G.2 Power losses of low-voltage switchgear and controlgear
- G.3 Power losses of conductors connecting low-voltage switchgear and controlgear
- G.4 Power losses of busbars
- G.5 Power losses of electronic devices
- Annex H (informative) Guidance on the impact of an adjacent wallon the assembly cooling surfaces
- Figure H.1 – Wall-mounted assembly
- Figure H.2 – Floor-standing assembly
- Annex I (informative) Operating current and power loss of copper conductors
- Table I.1 – Operating current and power loss of single-core copper cables with a permissible conductor temperature of 70 °C (ambient temperature insidethe enclosure: 55 °C)
- Table I.2 – Reduction factor k1 for cables with a permissible conductor temperature of 70 °C (extract from IEC 60364-5-52:2009, Table B.52.14)
- Table I.3 – Operating current and power loss of bare copper bars with rectangular cross-section, run horizontally and arranged with their largest face vertical, for DC and AC frequencies 16 2/3 Hz, 50 Hz to 60 Hz (ambient temperature inside the enclosure: 55 °C, temperature of the conductor 70 °C)
- Table I.4 – Factor k4 for different temperatures ofthe air inside the enclosure and/or for the conductors
- Annex J (informative) Guidance to magnetic and eddy-current power losses
- Figure J.1 – Power losses distribution for differentgland plates with the same rating
- Annex K (informative) Forced ventilation airflow calculation [Go to Page]
- K.1 General
- K.2 Ventilation airflow calculation
- Table K.1 – Factor k for altitudes above sea level
- Bibliography [Go to Page]