Lighting Engineering

LED Luminaire Junction Temperature Thermal Derating Factor Calculator

LED Luminaire Junction Temperature Thermal Derating Factor engineering calculator.

Quick Answer

Calculate LED Luminaire Junction Temperature Thermal Derating Factor

Calculator

Luminous Flux Derating Factor
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Result Interpretation

LED Luminaire Junction Temperature Thermal Derating Factor Calculator computes Luminous Flux Derating Factor in 1 using the defined engineering formula and the input values provided.

Worked Example

Verified calculation

Given:

  • Junction-to-Ambient Thermal Resistance = 12.5
  • Ambient Air Temperature = 298.15
  • LED Junction Temperature = 353.15
  • LED Power Dissipation = 45
  • Thermal Offset Constant = 273.15

Expected Result:

  • Luminous Flux Derating Factor = 0.93630216508106

Engineering Interpretation:

Under the given input conditions, the calculated result is: Luminous Flux Derating Factor = 0.93630216508106.

The actual numerical result is computed by the Runtime engine using the persisted tool definition. The values shown here come from automatically validated test cases.

Formula / Method

luminous flux derating factor = exp(-1.0 * (led junction temperature - ambient air temperature) / (junction-to-ambient thermal resistance * led power dissipation + thermal offset constant))

Formula family: formula_lighting_lighting_luminaire_thermal_derating_advisor

Variables

SymbolLabelRoleDescription
T_junction LED Junction Temperature INPUT LED Junction Temperature
T_ambient Ambient Air Temperature INPUT Ambient Air Temperature
theta_ja Junction-to-Ambient Thermal Resistance INPUT Junction-to-Ambient Thermal Resistance
P_dissipated LED Power Dissipation INPUT LED Power Dissipation
T_ambient_offset Thermal Offset Constant INPUT Thermal Offset Constant
luminous_flux_derating_factor Luminous Flux Derating Factor OUTPUT Luminous Flux Derating Factor
e e CONSTANT e = 2.718281828459 1

Calculation Steps

  1. Enter the led junction temperature in K.
  2. Enter the ambient air temperature in K.
  3. Enter the junction-to-ambient thermal resistance in K/W.
  4. Enter the led power dissipation in W.
  5. Enter the thermal offset constant in K.
  6. Step 1: Compute luminous flux derating factor.
  7. Read the luminous flux derating factor (1) from the results.

Engineering Summary

Calculate LED Luminaire Junction Temperature Thermal Derating Factor

Frequently Asked Questions

What does this calculator calculate?

The LED Luminaire Junction Temperature Thermal Derating Factor Calculator estimates Luminous Flux Derating Factor based on the input parameters you provide

What physical constants are used in this calculation?

This calculation uses the elementary charge (e = 2.718281828459 1). This is a fundamental physical constant that ensures the formula produces results in consistent engineering units

Why is led junction temperature important in this calculation?

led junction temperature is directly proportional to luminous flux derating factor. When you enter led junction temperature in K, the calculator uses it in the engineering formula to compute the output

How should I interpret the result luminous flux derating factor?

The calculator outputs luminous flux derating factor. The result is computed directly from the input values using the defined engineering formula

What units should I use for the inputs?

Enter each value in the units shown next to the input field: LED Junction Temperature (K), Ambient Air Temperature (K), Junction-to-Ambient Thermal Resistance (K/W), LED Power Dissipation (W), Thermal Offset Constant (K). Make sure all inputs use the specified units for consistent results

What assumptions does this calculator use?

This calculator uses automatically validated engineering formulas. Results are approximate and should be validated against site-specific conditions, applicable codes, and professional engineering judgment

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