Power distribution – Rockwell Automation 1770 Industrial Automation Wiring and Grounding Guidelines User Manual
Page 10
Industrial Automation Wiring and Grounding Guidelines
10
Publication 1770-4.1 – February 1998
You can connect the power supply directly to the secondary of a
transformer (Figures 7 and 8). The transformer provides dc isolation
from other equipment not connected to that transformer secondary.
Connect the transformer primary to the ac source; connect the high
side of the transformer secondary to the L1 terminal of the power
supply; connect the low side of the transformer secondary to the
neutral (common) terminal of the power supply.
Figure 7
Grounded ac Power-Distribution System with Master-Control
Relay
Notes:
1
2
To minimize emi generation, connect a suppressor across an inductive load. For suppressors to use, refer to 11 and
C or the Electrocube catalog.
In many applications, a second transformer provides power to the input circuits and power supplies for isolation
from the output circuits.
+ -
19241
Back-panel
Step-down
Transformer
2
FUSE
Multiple E-stop switches
Start
CRM
Grounded Conductor
CRM
CRM
L1
N or L2
GND
CRM
X
1
X
2
1FU
L1
2FU
L2
3FU
L3
L1
L2
L3
Disc.
H
1
H
2
H
3
H
4
Ground Bus
The I/O circuits form a net
inductive load switched by the
CRM contacts. Therefore, a
suppressor is needed
across the line at the load side
of the CRM contacts.
Suppressor
1
Suppressor
3
3
Connect a suppressor here to minimize emi generation from the net inductive load switched by the CRM contacts. In
some installations, a 1
m
f 220
W
suppressor (Allen-Bradley 700-N5) or 2
m
f 100
W
suppressor (Electrocube PN
RG1676-7) has been effective. For suppressors to use, refer to Figure 11 and Table C or the Electrocube catalog.
Suppressor
1
Grounding-electrode
Conductor to
Grounding-electrode
System
Equipment-
Grounding
Conductors
Connect when
applicable
Controller
Power Supply
Input
Module
Wiring
Arm
Output Module
Wiring Arm
Ouput
Actuator
To dc I/O
actuators/
sensors
Incomming
ac
User dc
Supply
Input
Sensor
Enclosure
Wall
To Motor
Starters
Power Distribution