Allen-Bradley MicroLogix 1200 User Manual page 140

F-6 System Loading and Heat Dissipation
Table F.10 Calculating the Current for Expansion I/O
(1)
Catalog Number
1762-IA8
1762-IF4
1762-IF2OF2
1762-IQ8
1762-IQ16
1762-IR4
1762-IT4
1762-OA8
1762-OB8
1762-OB16
1762-OF4
1762-OW8
1762-OW16
1762-OX6I
Total Modules (6 maximum):
(1) Refer to your expansion I/O Installation Instructions for Current Requirements not listed in this table.
Table F.11 Validating Systems using 1762-L40AWA, 1762-L40BXB, 1762-L40AWAR or 1762-L40BXBR
Maximum Allowable Values
Current:
600 mA at 5V dc 500 mA at 24V dc
System Loading:
15 Watts
Publication 1762-UM001D-EN-P - March 2004
n A
Number of Device Current Requirements (max)
Modules
at 5V dc (mA)
50
40
1 40
50
2 60
40
40
1 115
115
175
40
80
1 120
110
6 Subtotal 2:
Validating the System
The example systems shown in Table F.11 and Table F.12 are verified
to be acceptable configurations. The systems are valid because:
• Calculated Current Values < Maximum Allowable Current
Values
• Calculated System Loading < Maximum Allowable System
Loading
Calculated Values
Current (Subtotal 1 from Table F.9 + Subtotal 2 from Table F.10):
0 mA + 395 mA = 395 mA at 5V dc
System Loading:
= (395 mA x 5V) + (365 mA x 24V)
= (1975 mW) + (8760 mW)
= 10,735 mW
= 10.74 Watts
B n x A
Calculated Current
at 24V dc (mA) at 5V dc (mA)
0
50
105 40
0
0 120
50
50
0 115
0
0
165
90
140 120
110
395
120 mA + 245 mA = 365 mA at 24V dc
n x B
at 24V dc (mA)
105
0
0
140
245