User guide

Hardware Installation
890 USE 108 00 August 2001 127
System Power Requirements
External Power
Supplies
The Compact Controllers and some of the A120 I/O modules require an external
power source.
Power
Requirements
for a Compact
All the Compact Controllers require a 24 Vdc power source to operate. (Detailed
information appears in the note in this block.) Modicon offers the optional P120-000,
P120-125, P120-250, PRTU-252, and PRTU-258 Power Supplies. These are
designed in the A120 I/O module form factor, so that they can be inserted into any
available slot in a DTA backplane. (For details about the P120s, see Appendix A120
Power Supplies, p. 177.)
Note: It is not recommended that a single power supply be used to power the
Compact and its I/O. A separate supply is recommended to reduce the risk of field
noise affecting the controller’s operation. This is also beneficial in cases of single-
supply configurations, since a field point failure could cause the controller to shut
down.
The power requirement for the various PLC models is:
A984-1xx/E984-24x/251/255 PLCs is 24 Vdc -15% +20% maximum steady
state input current 1 A and 2 A peak.
E984-258/285 PLCs is 24 Vdc -30% +25% maximum steady state input current
1 A @24Vdc.
E984-265/275 PLCs is 24 Vdc -20% +25% maximum steady state input current
1.1 A @24Vdc.