Delta RMC151 - Manual (Page 1162)

RMC70/150 and RMCTools User Manual
Figure 1: SSR switching inductive inductive load: high-side configuration.
Example: Calculating maximum current for inductive load.
To calculate the maximum current through the SSR in the above diagram, we assume
zero SSR resistance:
Max. current = 24V / 480Ω = 50mA
Max. current = 12V / 480Ω = 25mA
In the 24V case, the maximum current is right at the maximum allowed by the SSRs. The
outputs may be overpowered if the coil resistance is reduced further. To calculate the
typical current through the SSR, we use the typical SSR resistance of 25W:
Typical current = 24V / (480Ω + 25Ω) = 47.5mA
Typical current = 12V / (480Ω + 25Ω) = 23.8mA
Discrete Inputs
The discrete inputs are compatible with signal levels ranging from 12V to 24V. Each input
draws a maximum of 2.6mA with a 12V or 24V input. Most PLC outputs can be connected
to the DI/O inputs directly. The exception is open collector (sinking) outputs. See the
discussion below for using sinking outputs.
Wiring Diagrams
The following are some input wiring diagrams:
Figure 4: Direct connection to Programmable
Controller.
Figure 5: Relay Connection from
Programmable Controller.
Using D8 Inputs with Open Collector Outputs
The D8's discrete inputs can be used with open collector (sinking) outputs. There are
three configurations that can be used to drive the D8 inputs from an open-collector
output:
1142 Delta Computer Systems, Inc.