Control panel cooling unit
Selection method
List of heat output by device
Control panel cooling unit
1. How to select panel cooler [indoor installation]
cooling capacity required to maintain the desired temperature inside panel can be calculated using the formula below.
Required cooling capacity [W]
= ①Total heat generation in panel [W] + ②Heat transfer rate [W/m2・℃] × (③Maximum ambient temperature [℃]-④ Desired temperature inside the board [℃]) × ⑤Control panel effective surface area [m2]
①Total heat generation inside panel
The total heat generated by the devices housed inside the panel.
*For the heat output of each device, please refer to the heat output list by device.
② Heat transfer rate
The rate at which heat penetrates from outside the panel into the panel.
This varies depending on the type of sheet metal and thickness, but for a 2mm thick steel plate it is approximately 5 [W/m2・℃].
③ Maximum ambient temperature
The highest temperature expected in environment in which the unit will be installed.
④ Desired temperature inside the panel
Desired internal temperature (recommended temperature is 35°C).
⑤ panel effective surface area
Total surface area of all surfaces in contact with the atmosphere of the target panel (for freestanding panels, surface area excluding the bottom).
2. How to select panel cooler [outdoor installation]
For outdoor installation, add the amount of energy from sunlight to the selection result of panel cooler for indoor installation calculated in 1. panel cooler selection method [indoor installation].
Required cooling capacity [W]
= Total solar intrusion heat + Necessary when using an indoor panel cooling capacity (1. panel cooler Refer to the item [Indoor installation] of the selection method)
How to calculate total solar radiation and heat penetration
1) Calculate the amount of heat entering through solar radiation.
The amount of sunlight varies depending on the installation location, date, time and orientation.
*Sample data of solar radiation on each surface (Tokyo area, July 22nd, clear skies) Unit: W/m²
| Top | north face | East side | south side | West side | |
|---|---|---|---|---|---|
| 11 o'clock | 1026.7 | 302.8 | 302.8 | 305.1 | 77.3 |
| 12 o'clock | 1064.0 | 78.3 | 78.3 | 325.9 | 78.3 |
| 13:00 | 1043.0 | 78.8 | 78.8 | 310.1 | 307.7 |
| 14:00 | 980.2 | 79.1 | 79.1 | 261.7 | 523.3 |
| 3pm | 872.1 | 80.7 | 80.7 | 179.8 | 715.3 |
Therefore, the required amount of solar heat radiation is calculated for each surface and the sum of the calculations is the amount of solar heat radiation required. The solar heat radiation for each surface can be calculated using the following formula.
Solar radiation on each surface [W/m²] ×
Terminology
- Heat transfer coefficient (W/m² °C): Ratio of the amount of heat that enters (or dissipates) by heat conduction to the area when there is a temperature difference between the ambient temperature (the temperature at which the enclosure surface rises) and the desired temperature. panel varies depending on the board thickness and material, but is defined as 5 to 6 W/m² °C by the Panel Heat Related Equipment Manufacturers Association.
- "Heat transfer coefficient on the outside of the housing (W/m²・℃)" - It is estimated to be approximately 10W/m²・℃ when there is no wind, and approximately 15W/m²・℃ when the wind speed is 1 to 2 m/s. The higher the wind speed, the greater the heat transfer coefficient.
- "Casing surface temperature rise (equivalent to outside air temperature rise)": This refers to the equivalent temperature rise due to solar radiation.
From the above, we can see that the temperature will vary depending on the area where the panel is installed, the color and condition of the panel surface, the condition of the panel's outer walls (thickness, double structure, installation of sunshades, etc.), and the condition of the wind circulating outside the panel.
As an example, let's calculate using panel with the following conditions.
◎ Height 2000mm, width 1000mm, depth 500mm◎ Door facing south◎ Tokyo area, July 22nd, clear skies, 2pm, no wind◎ Panel thickness 2mm, paint color: light beige, wall surface is single-layer structure
| Face position | solar radiation (W/m²) |
solar absorptance | Outer surface of the housing heat transfer coefficient (W/m²・℃) |
Fairly open air Temperature rise (℃) |
heat transfer rate (W/m²・℃) |
Area of surface (m²) | Solar heat (W) |
|---|---|---|---|---|---|---|---|
| Top | 980.2 | 0.5 | 10 | 49.01 | 5 | 0.5 | 122.5 |
| north face | 79.1 | 0.5 | 10 | 3.955 | 5 | 2 | 39.6 |
| East side | 79.1 | 0.5 | 10 | 3.955 | 5 | 1 | 19.8 |
| south side | 261.7 | 0.5 | 10 | 13.085 | 5 | 2 | 130.9 |
| West side | 523.3 | 0.5 | 10 | 26.165 | 5 | 1 | 130.8 |
| Total solar radiation and heat infiltration | 443.6 | ||||||
Caution! As the surface of the disc becomes dull over time, the absorption rate changes, so it is necessary to select a product with safety factor in mind.
3) Select the required cooling capacity by applying it to capacity characteristics graph of each panel cooler.
<<Notes on selection>>
- Please note that the amount of heat generated by inverters, servo amplifiers, etc. varies greatly depending on how they are used, motor torque, etc.
- For inverters with a rating output of 50 kW or more, the amount of heat generated varies greatly depending on the manufacturer, so please check with the manufacturer.
- When selecting a model, please select one that exceeds the required rating capacity and cooling capacity.
- Please note that capacity calculated using the above formula are only a guideline and are not absolute values.
- Please note that depending on the sealing of the panel, the position with the heating element, and the convection in the chamber, the expected cooling capacity may not be obtained.
- Dirty filter and deterioration of the fan motor may lead to a decrease in cooling capacity, so please perform regular maintenance.
List of heat output by device
1. power supply and transformer equipment
| Equipment stored inside the panel | Heat generation (reference value) | remarks | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Small transformer | rating capacity
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| Large transformer (single-phase) |
rating capacity
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| Large transformer (three phase) |
rating capacity
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| Voltage regulator | Approximately 10% of the rating capacity | |||||||||||||
| large resistor | About 1/3 of rating capacity | |||||||||||||
| constant voltage power supply | rating capacity
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| uninterruptible power supply supply (UPS) |
Output Capacity
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| DC stabilized power supply (switching regulator) |
Approximately 20 to 30% of the rating capacity |
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| Low-Voltage Capacitor | Approximately 0.2 to 0.3% of rating capacity |
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2. Amplifiers
| Equipment stored inside the panel | Heat generation (reference value) | remarks | ||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AC servo amplifier | rating capacity
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| inverter | rating Output
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| AC reactor (200V system) |
rating capacity
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| AC reactor (400V system) |
rating capacity
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| DC reactor (200/400V system) |
rating capacity
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| Braking resistor and control unit (200/400V system) |
rating capacity
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| Thyristor (single-phase) |
rating current
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| Thyristor (three phase) |
rating current
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3. Wiring equipment
| Equipment stored inside the panel | Heat generation (reference value) | remarks | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Circuit breaker (MCCB) |
rating capacity
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| Earth leakage circuit breaker (ELCB) | rating capacity ~225A MCCB+ 5W approx. ~400A MCCB+30W (earth leakage electronic circuit, etc.) |
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| electromagnetic contactor | rating capacity
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| Thermal overload relay (thermal) |
rating current
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| electromagnetic relay | Approximately 5W per unit |
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4. Control equipment
| Equipment stored inside the panel | Heat generation (reference value) | remarks | ||||||
|---|---|---|---|---|---|---|---|---|
| Small relay |
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| Solid State Relay (SSR) |
Load current value x 1.8W | |||||||
| temperature controller | current consumption is considered to be the amount of heat generated. | |||||||
| PLC | small PLC AC power supply type
power consumption of a standard PLC power supply unit |
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| PC | power consumption of power supply unit | |||||||
| LCD monitor | Approximately 20W per unit | |||||||
| Touch-panel | Approximately 100W per unit |
5.Other
| Equipment stored inside the panel | Heat generation (reference value) | remarks | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| fan motor |
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Note! The above heat output data for each device is based on data published by the Panel Heat-Related Equipment Industry Association, with additional data that we have independently researched.
The heat output of each device is a guideline, so if you would like to know the exact heat output, please contact the device manufacturer.
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