60890 Pdf | Iec Tr

Temperature rise inside electrical enclosures is a critical factor affecting component lifespan, insulation performance, and safety. Full testing per IEC 61439-2 can be costly and time-consuming. IEC TR 60890 (Edition 2.0, 2014) – “A method of temperature-rise assessment by extrapolation for partially type-tested assemblies (PTTA) of low-voltage switchgear and controlgear” – offers an alternative calculation method for standardized enclosures.

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Application of IEC Technical Report 60890 for Temperature Rise Verification in Enclosed Switchgear and Controlgear Assemblies

While the IEC TR 60890 method is powerful, it has constraints that any engineer using the PDF must understand:

Imagine a wall-mounted distribution board (H=1800mm, W=800mm, D=300mm) containing: Temperature rise inside electrical enclosures is a critical

Step 1 – Ae (wall-mounted):
The back side against wall does not dissipate heat.
Ae = (H×W) front + (H×D)×2 sides + (W×D) top = 1.44 + 1.08 + 0.24 = 2.76 m².

Step 2 – Loss P = 300W (inside limit for wall-mounted: <1000W).

Step 3 – Mounting factor: Wall-mounted, with ventilation openings ~1.5% → c factor from Table 3 in the PDF is roughly 1.45. Warning: Avoid websites offering "free IEC TR 60890

Step 4 – Calculation:
ΔT₀ = 1.45 × (300)^0.7 (using exponent for wall-mounted case)
ΔT₀ ≈ 1.45 × 52.5 ≈ 76 K rise at center.

Step 5 – Top correction: For height 1.8m, add ~5K. Final top internal temperature rise = 81 K above ambient. At 35°C ambient, internal air reaches 116°C – which may exceed component limits (typical max 70°C for MCBs). The designer would then need to reduce load or improve ventilation.

This simple walkthrough is why engineers urgently seek the PDF – it enables early design correction without a lab.