Operation | 7
OPERATING MODES
The operating modes of the RAU are selected from the front panel (in Local mode) or over the remote bus (in Remote
mode).
AUTO MODE
In Auto mode the On-Line/Standby status of the amplifiers is controlled automatically without operator intervention.
Amplifier path control is locked out from both the front panel and the remote bus.
In Auto mode, switching is the direct result of a change in amplifier alarms. Switching from Manual to Auto mode will cause
all amplifier alarms to be treated as new alarms for switching purposes.
Figure 3-1. Automatic Switching Decision Process for a Failed Amplifier
MANUAL MODE
When the RAU is in Manual mode the On-Line/Standby status can be controlled from the front panel when the unit is
in LOCAL mode, or can be controlled by the remote bus when the unit is in REMOTE mode. Amplifier faults are still
monitored and reported, but they will have no effect on the On-Line/Standby status.
LOCAL MODE
When the RAU is in LOCAL control mode, operational functions and parameters can be controlled and entered from the
front panel. Remote control of these functions and parameters is locked out. However, the control unit will still respond to
remote monitoring of RAU operation.
REMOTE MODE
When the RAU is in REMOTE control mode, operational functions and parameters can only be controlled from the remote
bus. All control and parameter values can be viewed from the front panel. Changes to control and parameter values are
BEGIN
Switch Backup Amplifier
On-Line
**S
witch Backup Amplifier
in from low priority Online
path to high priority Online
Any other unit
fault have
greater priority?
Unit in Auto
Mode
A Primary
Amplifier
has failed
A Backup
Amplifier is
available
Yes
Yes
Yes
Yes
No
No
No
No
**T
his is only available in a 1:2 model, otherwise pass directly on to top of flowchart without switching.