Operating Modes - ABB ACH550 User Manual

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Hand Key
The Hand key can be used to manually start the motor when the bypass has been
selected as the power source for the motor.
OFF Key
The OFF key can be used to manually stop the motor if the motor has been running
on bypass power.

Operating Modes

Drive Mode
Under normal conditions the system is in the Drive mode. The ACH550 drive
provides power to the motor and controls its speed. The source of the drive's start/
stop and speed commands is determined by the Auto or Hand mode selection of the
drive's keypad. Commands come from the control terminals (or serial
communication) when the Auto mode has been selected or from the drive keypad
when the Hand mode has been selected. The user can normally switch to the Drive
mode by pressing the Drive key on the bypass keypad.
Bypass Mode
In the Bypass mode, the motor is powered by AC line power through the bypass
contactor. The source of the bypass start/stop commands is determined by the Auto
or Hand mode selection of the bypass' keypad. Commands come from the control
terminals when the Auto mode has been selected or from the bypass keypad when
the Hand mode has been selected. The user can normally switch to the Bypass
mode by pressing the Bypass key on the bypass keypad. Alternative methods of
bypass control called Overrides are also available. Refer to the following
descriptions of the Override modes.
Fireman's Override Mode
In the Fireman's Override (Override 1) mode, the motor is powered by AC line power
through the bypass contactor. The source of the start command is internal and
unaffected by external stop commands.The user can switch to the Fireman's
Override mode by closing the Fireman's Override input contact. When the Fireman's
Override input contact is closed, the system is forced to bypass and runs the motor.
The Automatic Transfer LED flashes green when the system is in override. While in
Fireman's Override the system does not respond to any other inputs including
overloads, faults, safeties and enables. Fireman's Override is designed for "Run to
Destruction" operation. Normally when the Fireman's Override input contact is
switched from closed to open, the system returns to the operating mode that existed
prior to entering Override and can be controlled using the Drive and Bypass keys.
The exception to this is when the Bypass Override (Override 2) input contact is
closed, in which case the system switches to Bypass Override mode.
Bypass Override Mode
In the Bypass Override (Override 2) mode, the motor is powered by AC line power
through the bypass contactor. The source of the start command is internal and
unaffected by external stop commands.The user can switch to the Bypass Override
mode by closing the Bypass Override input contact. When the Bypass Override input
Start-up
E-Bypass Configurations for ACH550 Drives