# Thermal control equipmentChoosing a Control Panel Cooling unit

ENC Series

Those requesting for model selection via the Web By entering the detailed information for the model selection,
the calculations will be carried out automatically to select a model that matches the site.

# How to choose a model in the ENC series

## 1. How to select a control panel cooling unit [indoor installation]

The cooling capacity required to maintain the inside of the control panel at the desired temperature can be calculated by the following equation.

### (1) Total heat generated inside the control panel

Total amount of heat generated by the devices stored inside the panel.
*Refer to the heat generation list by device for the amount of heat generated by each device.

### (2) Heat transfer coefficient

The heat transfer coefficient represents the proportion of heat trying to penetrate inside the panel from the outside.
It varies depending on the type and thickness of the sheet metal, but in steel plates with a thickness of 2 mm, it is about 5 [W/m2· °C].

### (3) Maximum ambient temperature

Temperature that is expected to be the highest in the installation environment.

### (4) Desired temperature inside the panel

Desired temperature inside the panel (recommended temperature is 35 °C).

### (5) Effective surface area of control panel

Total surface area of all the surfaces in the target control panel that are in contact with the atmosphere (for autonomous panels, this is the surface area excluding the bottom surface).

## ２． How to select a control panel cooler [outdoor installation]

For outdoor installation, the model is selected by adding the amount of the energy from sunlight to the figure of the control panel cooler selected for indoor installation that is calculated in (1) How to select a control panel cooler [indoor installation].

Required cooling capacity [W]
= Total solar radiation penetration heat + cooling capacity required for indoor panel (Refer to Section 1. How to select a control panel cooler [indoor installation])

### How to determine the total solar radiation penetration heat

#### 1) Calculate the amount of penetration heat due to solar radiation.

The amount of solar radiation depends on the installation location, date, time, and orientation.

★Solar radiation sample data of each surface (Tokyo area, July 22 weather clear) Unit: W/m²

Sky side North side 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 o’clock 1043.0 78.8 78.8 310.1 307.7
14 o’clock 980.2 79.1 79.1 261.7 523.3
15 o’clock 872.1 80.7 80.7 179.8 715.3

Therefore, the required solar radiation penetration heat will be the sum of all the values calculated for each side. The solar radiation amount of each side is determined by the following formula.

Total solar radiation penetration heat = Housing surface temperature rise on each side (equivalent outside air temperature rise) × heat transfer coefficient × surface area of each side
Equivalent outside air temperature rise [°C] =
olar radiation on each side [W/m²] ×
Solar absorption rateHousing outer surface heat transfer coefficient [W/m²・℃]
##### Description of terms
• “Heat transfer coefficient (W/m²・ °C)” ... When there is a temperature difference between the ambient temperature (temperature rise on the housing surface) and the desired temperature, the opposing surface area ratio of the penetration (or dissipation) heat due to heat transfer varies according to the plate thickness and material of the control panel but this is defined as 5 to 6 W/m²・ °C by the Thermal Solution Equipment for Cabinet Technical Association.
• Housing external heat transfer coefficient (W/m²・°C) ... This value is believe to be about 10 W/m² °C when there is no wind, and about 15 W/m² °C at a wind speed of 1 to 2 m/s. The higher the wind speed, the greater the heat transfer rate.
• “Temperature rise on housing surface (equivalent outside air temperature rise)”... Equivalent rise in the air temperature due to sunlight.

From the above, it can be seen that the value varies depending on the installation area, color and condition of the panel surface, condition of the outer walls of the panel (thickness, double structure, installation of sunshade, etc.), condition of the wind flowing over the panel and so on.

As an example, we’ll try to calculate it with the control panel under the following conditions.

◎Height 2000 mm, width 1000 mm, depth 500 mm ◎ door surface facing south ◎Tokyo district, July 22, weather clear, 14 o’clock, windless ◎thickness 2 mm, paint color: light beige, single structure wall surface

(W/m²)
Solar absorption rate Outer surface of housing
Heat transfer rate
(W/m²・℃)
Equivalent outside air
Temperature rise
(℃)
Heat transfer coefficient
(W/m²・℃)
Sky side 980.2 0.5 10 49.01 5 0.5 122.5
North side 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 penetration heat 443.6

CautionSince the absorption rate changes when the surface of the panel becomes dull together with use over the years, it is therefore necessary to select a model with the safety factor in mind.

#### 3) Select the model by applying the required cooling capacity above to the capacity characteristic graph of each control panel cooler.

<Notes on selection>

1. Note that the amount of heat generated varies greatly depending on how the inverter and servo amplifier are used and the motor torque etc.
2. For inverters with a rated output of 50 kw or more, check with the manufacturer as the amount of heat generated varies greatly depending on the manufacturer.
3. When selecting a model, select one that exceeds the required rating capacity and cooling capacity.
4. Note that the capacity calculated by the above formula is just an estimate and not an absolute value.
5. Be extra careful because the expected cooling capacity may not be obtained depending on the sealing of the control panel, position relative to the heating element, and the air flow inside the control panel.
6. Carry out regular maintenance as dirty filters, deterioration of the fan motor etc. may lead to a drop in the cooling capacity.

## List of calorific values by equipment

### 1. Power supplies and transformers

Storage devices inside panel Calorific value (recommended value) Remarks
Small transformer Rated capacity
• The smaller the transformer, the larger the heat generation ratio.
Large transformer
(Single phase)
Rated capacity

Large transformer
(3-phase)
Rated capacity

Voltage regulator About 10% of the rated capacity
Large resistor About 1/3 of the rated capacity
Constant voltage power supply Rated capacity

Uninterruptible power supply
(UPS)
Output capacity
• The smaller the transformer, the larger the heat generation ratio.
• The amount of heat generated is the value at which the storage battery is in the floating charge state.
• Regular inverter power supply system
DC stabilized power supply
(Switching regulator)
About 20-30% of the rated capacity
• The smaller the transformer, the larger the heat generation ratio.
• Amount of heat generated at 100% of the rated capacity.
Low voltage capacitor About 0.2-0.3% of the rated capacity
• Rated capacity is in kVA.
Reference
(1ｋVA＝265.3μF)

### 2. Amplifiers

Storage devices inside panel Calorific value (recommended value)Remarks Remarks
AC servo amplifier Rated capacity
• The smaller the transformer, the larger the heat generation ratio.
• Amount of heat generated at 100% of the rated capacity.
• The value indicated is a general estimate.。
Inverter Rated output
• The smaller the transformer, the larger the heat generation ratio.
• Amount of heat generated at 100% of the rated capacity.
• The value indicated is a general estimate.。
AC reactor
(200 V system)
Rated capacity
• Notation for amount of heat generated.
• The amount of heat generated at an input voltage of 50 Hz, a voltage balance of 0%, and a motor load of 100%.
AC reactor
(400 V system)
Rated capacity
• Notation for amount of heat generated.
• The amount of heat generated at an input voltage of 50 Hz, a voltage balance of 0%, and a motor load of 100%.
DC reactor
(200/400 V system)
Rated capacity
• Notation for amount of heat generated.
Braking resistance and control unit
(200/400 V system)
Rated capacity
• Notation for amount of heat generated.
• Amount of heat generated at 100° control torque and 5% braking frequency.
Thyristor
(Single phase)
Rated current
• Notation for amount of heat generated.
Thyristor
(3-phase)
Rated current
• Notation for amount of heat generated.

### 3. Wiring equipment

Storage devices inside panel Calorific value (recommended value)Remarks Remarks
Circuit breaker for wiring
(MCCB)
Rated capacity
• Amount of heat generated at 100% of the rated current.
• For 3P (proportional to polarity.)
Electrical leakage circuit breaker (ELCB) Rated capacity
- 225A MCCB + About 5 W
- 400A MCCB + About 30 W (electrical leakage circuit unit, etc.)
• Amount of heat generated at 100% of the rated current.
• For 3P (proportional to polarity.)
However, the electrical leakage circuit unit acts independently of the polarity.
Electromagnetic contactor Rated capacity
• Amount of heat generated at 100% of the rated current.
(Themal)
Rated current
• Amount of heat generated at the maximum current value set.
Electromagnetic relay About 5 W per unit
• Amount of heat generated at 100% of the rated current.

### 4. Control equipment

Storage devices inside panel Calorific value (recommended value)Remarks Remarks
Small relay
 Mini relay 1～2W/Pieces Power relay 2～3W/Pieces

Solid state relay
(SSR)
Temperature controller Current consumption is considered to be the amount of heat generated.
PLC Compact PLC
AC power type
 I/O score 10 to 40 points 30 to 50 W I/O score 64 points and above I/O score × 1 W DC power type I/O score × 0.5 W

Approximately the power consumption of a standard PLC power supply unit

PC Approximately the power consumption of the power supply
LCD monitor About 20 W per unit
Touch panel About 100 W per unit

### 5. Others

Storage devices inside panel Calorific value (recommended value)Remarks Remarks
Fan motor