"The Heat balance, Which Consist of comparing the power released by the devices with the power exchanged spontaneously through the wall of the enclosure, allows us to calculate the internal temperature obtained in the enclosure, with no thermal accessories"
1. Characteristics of the Enclosure
H = Height (m) W = Width (m) D = Depth (m)
H= 2.0 W= 1.2 D= 0.4
Position of the Enclosure Location according to IEC890 ratio Formula for Calculating S (mý)
Accesible from every side S = 1.8 x H x (W + D) + 1.4 x W x D
Placed against a wall S = 1.4 x W x (H + D) + 1.8 x D x H
On the end when suited S = 1.4 x D x (H + W) + 1.8 x W x H
"On the end when suited, Placed against a wall" S = 1.4 x H x (W + D) + 1.4 x W x D
In the middle when suited S = 1.8 x W x H + 1.4 x W x D + D x H
"In the middle when suited, Placed against a wall" S = 1.4 x W x (H + D) + D x H
"In the middle when suited, Placed against a wall with top covered" S = 1.4 x W x H + 0.7 x W x D + D x W
Considering the panel to be placed against a wall
S= [1.4x1.2x(2+0.4)] + (1.8x0.4x2)
S= 5.47 m2
2. Thermal power dissipated by the operational components
A list of electrical components dissipating power is detailed:
Component Details Power Dissipated x number of components Total Power Dissipated (W)
1 Push button and 36 ( 2.4 W lamps) & 3 Selector Switches 1.3x40 52
1 MCCB of 100 A 4P =24x1= 24
1 115A 4P contactor 31x1 =31
22 MCB of 16 A 2P 5.2x22 =114
7 MCB of 25A 4P 6.5x7 =46
1 MCB of 6A 2P 2x1= 2
22 RCCB of 16 A 2P 2x22= 44
7 RCCB of 25A 4P 3.9x7= 27
Power Dissipated by 1X40X5 BUSBARS - 49
"Power Dissipated by fuses, CTs,meters & auxilary relays(approximate)" - 21
The power dissipated by each of the installed components.
Pd= 52+32+41+114+81+1+44+36+49+21
Pd= 410 W
3. Characterisitcs of the environment air
Maximum Ambient Temperature Te max = 58 ºC
Minimum Ambient Temperature Te min = 20ºC
Average relative humidity RH = 100%
4. Average Desired internal temperature
They are defined by the nature of the components and characteristics of the environment air.
Maximum internal temperature Ts max = 60 ºC
Minimum internal Temperature Ts min = 25 ºC
5. Final tempeerature inside the enclosure with no thermal system
Maximum internal temperature: Ti max = Pd /(KxS)+ Te max
Maximum internal temperature: Ti max = 410/30.096 + 58
30.096
Maximum internal temperature: Ti max = 72 ºC
Minimum internal temperature: Ti min = Pd /(KxS) + Te min
Minimum internal temperature: Ti min = 410/30.096 + 20
Minimum internal temperature: Ti min = 34 ºC
K = 5.5 W/mý/§C for an enclosure made of Painted Sheet Steel
6. Determining the type of thermal device and its power : Psyst
If Ts min < Ti min No need for a thermal system
If Ts min > Ti min Need for Thermal System: resistant heater
If Ts max < Ti max Need for a Thermal system: Ventilation, fan, exchanger, cooling unit.
If Tsmax > Timax No Need for a thermal system; a circulation fan may be used to even out the temperature.
| 1.
Permanent operation of the switchboard |
| Psyst =
K x S (Ts min - Te min )-Pd |
| 1.
Discontinous operation of the switchboard |
| Psyst = K x S (Ts min - Te
min ) |
7. Solutions with fans
The use of Fan and Grille is recommended
1 fans NSYCVF300M230PF +1 grids NSYCAG223LPF
Airflow Necessary 169.1712 m?/h
Airflow provided 260 m?/h( 1 fans)
Highest Temperature That the Enclosure will attain without cooling: > 55§C
(The EN60439 international standard recommends not to exceed 70øC)
Fan Characteristics
Dimensions 268 x 248 x 116 mm
Weight : 1.3 kg
Voltage : 230 V
Frequency (Hz) 50 Hz
Protection degree IP54
Function EXTERNAL FAN
Filter Filter included(Filter standard)
Electrical output (W) 36W/ 37W
Imax (mA) "0,171A/ 0,163A"
are there any errors in this calculation?
Errors In Heat Dissipation Calculation For An Enclosure
Re: Errors In Heat Dissipation Calculation For An Enclosure
