Instructions / Assembly

Power Considerations for Control Systems
Page B-2
Power Requirements and Maximum Run Length
Each Control Device used in your system has a different load (draw) and each PCD
can support a different total load (supply.) There are logical steps for determining the
total load of your network and verifying that the supply is sufficient:
Step 1: Determine the maximum available current of your supply, be it a PCD or
other Power Supply. Convert this to the maximum number of Unit Loads
if necessary.
Step 2: Calculate the sum required load of each Control Device, expressed in
unit loads
Step 3: Verify that the Sum from Step 2 <= the maximum available power from
your supply in Step 1.
If this verification fails (the Sum of required loads is > than the available supply) you
can either use an external power supply or reduce the number of control devices. Or,
contact our Technical Services department for help.
Figure B-1: Load Rating Verification Formula
Power Control Devices - Available Supply Current
The EZ-MAX Plus cabinets are designed to be able to power external control loads
from the internal power supply.
One Unit Load = 25mA = .025A
Control Station A Unit Load
X
Quantity of Station A's attached
+
Same formula
for any other attached
control Station
Control Station B Unit Load
X
Quantity of Station B's attached
<
+
Power Supply's
Available Unit Load
The sum of all devices connected to all power output
terminals can not exceed the Maximum number of Unit Loads
available in the PCD or supply.