3 Power Redundancy
The terminology for power sources, supplies, and converters is often confused. An external power source is provided for the
electronics, which have internal power supplies that convert the source voltage to low-level regulated busses for circuit
boards. In many cases, there is also a wetting voltage required for contact inputs, analog inputs, and power feeds for field
solenoids that are powered from the control.
The control system accepts one, or redundant, 24 V dc, 125 V dc, and 115/230 V ac sources that can be mixed in any
combination. Internal power supplies convert the source voltage to 28 V dc for the controller, IONet switches, and the
distributed I/O modules. Internal supplies are normally non-redundant for simplex control systems, but can be provided as
dual redundant, if required. Dual redundant power supplies are provided for dual redundant control systems, and dual/triple
redundant power supplies are provided for triple redundant controls systems. An exception is remote I/O panels with
non-critical I/O. These panels normally have a single power supply regardless of whether the controllers are redundant or
non-redundant. But, they can be supplied in redundant pairs too, if required. Additional redundancy options are available.
Power Sources, Converters, and Supplies
Different power sources can be provided for the internal electronics and the wetting voltage for contact inputs, transducers,
and solenoid power. For example, redundant 230 V ac sources can be converted to 28 V dc for the internal electronics. If 125
V dc wetting voltage is needed for contact inputs or field solenoids, it can be provided directly from the station battery or
from redundant 230 V ac to 125 V dc converters in the control.
Diagnostics monitor power sources and power supplies for fault detection and to enable online repair.
Mark VIe Controls System Redundancy Options