Heat Radiation Countermeasures - Mitsubishi MELDAS MDS-C1 Instruction Manual

1-3-6 Heat radiation countermeasures

In order to secure reliability and life, design the temperature in the panel so that the ambient
temperature of each unit is 55°C or less.
If heat accumulates at the top of the unit, etc., install a fan so that the temperature in the panel remains
constant.
(Note)
Due to the structure, heat easily accumulates at the top
of the unit. Install a fan in the power distribution panel to
circulate the heat at the top of the unit.
Please refer to following method for heat radiation countermeasures.
Calculate total heat radiation of each
mounted unit (W)
Calculate cabinet's cooling capacity
≤
W W1
Comparison of W and W1
Selection of heat exchanger
Mounting design
Collection of internal temperature rise
distribution data
≤
∆ T
10°C
Evaluation
Improvements
Completion
Examples of mounting and temperature measurement positions (reference)
Measurement position (example)
1. Installation
(W1)
W>W1
∆ T>10°C
Relay, etc.
<Hypothetical conditions>
(1) Average temperature in cabinet : T
(2) Cabinet peripheral temperature : Ta ≤ 0°C to 45°C
(3) Internal temperature rise value
<Supplement>
1) Refer to Specifications Manual, etc. for the heat
generated by each unit.
2) Enclosed cabinet (thin steel plate) cooling capacity
calculation equation
W1 = U × A × ∆T
2
U: 6W/m × °C (with internal agitating fan)
2
4W/m × °C (without internal agitating fan)
A: Effective heat radiation area (m
(Heat dissipation area in panel)
Sections contacting other objects are excluded.
∆T: Internal temperature rise value (10°C)
3) Points of caution for heat radiation countermeasures
when designing mounting state
•
Layout of convection in panel
•
Collect hot air at suction port in heat exchanger
cabinet.
4) Understanding the temperature rise distribution in the
panel
∆T (average value) ≤ 10°C
∆T (maximum value) ≤ 15°C
max
R (inconsistency) = (∆T
(Evaluate existence of heat spots)
Flow of
air
Unit
1 - 13
(Inside panel)
Wind speed 2m/s or more
≤ 55°C
∆T =T–Ta
:
max
2
)
– ∆T ) ≤ 6°C
max min
Flow of air
= 10°C