Operation Box Heat Radiation Countermeasures - Mitsubishi Electric MELDAS 600 Series Connection Manual

3.2.2 Operation Box Heat Radiation Countermeasures

Please refer to following method for heat radiation countermeasures method.
<Hypothetical conditions>
(1) Average temperature in cabinet : 55°C
(2) Cabinet peripheral temperature : Ta ≤ 0°C~45°C
(3) Internal temperature rise value
Procedures for heat design and verification
Calculate total heat generation of each
mounted unit (W)
Calculate cabinet's cooling capacity
W≦W1
Comparison of W and W1
Selection of heat exchanger
Collection of internal temperature rise
distribution data
△T≦10°C
Refer to "Section 3.1 General Specifications" for the heating value of each unit.
With the operation box, heat could accumulate at the top of the control unit, so install a circulation fan.
Install a circulation fan in the panel when the following conditions are not satisfied.
Evaluation standards for internal temperature rise distribution data
CHAPTER 3 INSTALLATION
3.2 Designing Conditions of Operation Box
Example of heat radiation countermeasures
(W1)
W>W1
Mounting design
Evaluation
△T>10°C
Improvements
Completion
∆T (average value) ≤ 10°C
∆Tmax (maximum value) ≤ 15°C
: ∆T = T − Ta (max) = 10°C
<Supplement>
(1) Refer to "3.1 General Specification" for
the heat generated by each unit.
(2) Enclosed cabinet (thin steel plate)
cooling capacity (W1) calculation
equation
W1 = U × A × ∆T
2
U : 6W/m
... with internal circulation fan
2
4W/m
... without internal circulation fan
A : Effective heat radiation area (m
∆T : Internal temperature rise value
(Area where heat can be radiated from
cabinet)
<Caution>
When calculating the effective heat
radiation area, do not include the parts
that contact other objects.
(3) Points of caution for heat radiation
countermeasures when designing
mounting state
∗Consider convection in cabinet
(eliminate heat spots)
∗Collect hot air at suction port in heat
exchanger panel.
(4) Evaluation standards for internal
temperature rise distribution data
∆T (average value) ≤ 10°C
∆Tmax (maximum value) ≤ 15°C
R (inconsistency ∆Tmax − ∆Tmin) ≤ 6°C
(Evaluate existence of heat spots)
10
× °C
× °C
(10°C)
2
)