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Section 4: Glossary of Control Functions
Normal Temperature
Refer to Temperature Staging.
Override
The RAC2-8 allows manual control of units from the display and also
from switches inside the enclosure. To manually turn all units ON refer
to Manual Override. To manually select units to be ON during a control
power failure refer to Power Failure Mode.
Manual Override control from the display includes Force ON, Force
OFF, and Restore to normal operation. If any unit is Forced ON or OFF
a warning message is recorded and the Alarm Present light is
illuminated, but the audible alarm (horn) is not sounded. Changes of
status messages are displayed at a local terminal if one is connected.
While an Override screen is displayed, alarm messages are stored but
not displayed.
Force ON of any unit
Selected from the Override screen at the display. This action causes the
selected unit to be turned ON and held ON until further action is taken.
The unit remains ON until it is Forced OFF or Restored to normal.
Force OFF of any unit
Selected from the Override screen at the display. This action causes the
selected unit to be turned OFF and held OFF until further action is
taken. The unit remains OFF until it is Forced ON or Restored to
normal.
Restore to normal
Selected from the Override screen at the display. This action returns the
selected unit to the programmed control of the RAC2-8. The unit
returns to its operating status (Running or Standby) as defined in
Unit/Zone Setup.
Password
A four digit number used to limit access to setup information and
clearing of alarms. A Password (if active) is required for entry to the
Main Menu. Assign a new Password from the display. A Password of
“0000” disables the Password function at the local display: “TERM”
disables the password at a local terminal. The Password is always
required for a remote terminal (through a modem).
Power Failure Mode
During a failure of power to the RAC2-8, units can be programmed to
be ON by manually setting jumpers inside the enclosure. This assumes
that power will be available to the units. When power is restored to the
RAC2-8, all units programmed to be Running during normal operation
are sequentially started, separated by the Restart Delay.
Compare this mode with Emergency Power operations which is
selectable from the display and applies to power being available from a
standby source.
Liebert RAC2-8 • 33