Example Heat Dissipation Calculation - Allen-Bradley SLC 500 User Manual

Example Heat Dissipation
Calculation
Peripheral Device
Slot Number Cat. No.
0 1747-L511
1 1746-BAS
2 1746-IA8
3 1746-OV8
Peripheral 1747-DTAM
Device
User Power to NA
Peripheral
(1)
The user power on the 1746-P1 power supply for chassis 2 is being used to power a peripheral (100 mA at 24V dc).
(2)
This output card uses 5.5 W because only 10 points are on at any one time. Using the calculated watts formula - (number of points energized x watts per point) + minimum
watts = heat dissipation of module - the calculated watts for the 1746-OW16 module is 5.5 W: (10 points x.33) + 5.17 = 5.5 W.
If your controller consisted of the following hardware components,
you would calculate heat dissipation as shown in the worksheet on
page 268.
DTAM
Slot
The following table details the total watts dissipated by the modules
and peripheral devices in the above SLC 500 controller. The numbers
were taken from the tables on page 263.
Chassis 1
Min Watts Max Watts
1.75 1.75
3.750 3.80
0.250 2.40
0.675 6.90
2.500 2.50
NA NA
Calculating Heat Dissipation for the SLC 500 Control System
Chassis 1
0 1 2 3
Slot Number Cat. No.
4 1746-IA16
5 1746-IA16
6 1746-OW16
7 1746-OW16
NA NA
NA NA
Chassis 2
Slot
4 5 6 7
User Power to
Peripheral
Chassis 2
Min Watts Max Watts
0.425 4.800
0.425 4.800
5.170
(2)
5.500
5.170 5.700
NA NA
(1) NA
2.400
Publication 1747-UM011G-EN-P - June 2008
267