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14
3.3 Using the Electronic Bypass Configuration Switches
The bypass configuration switches are a group of four switches that are
used to tailor the
Automatic Bypass
Fire Alarm
Damper Control
Fireman’s Override
Switch 1:
Enables or disables the automatic bypass function. With switch 1
in the
ON
position, and the electronic bypass package operating in VFD
mode, a VFD fault will cause both the operation and run modes to be
cancelled (stopping the motor) and the VFD Fault LED to illuminate in the
Alarm Display.
With switch 1 in the
OFF
position, a VFD fault will cause the bypass
contactor to close, keeping the motor running on line power. As with the
switch 1
ON
configuration, the drive fault will be displayed in the Alarm
Display. See section 3.8.2 .
Switch 2:
Controls the bypass response to a fire alarm condition. The Fire
Alarm (switch 2) default
ON
position causes the opening of the fire alarm
input (TB2-6) to stop the motor independent of whether it was being run by
the VFD or the line. When the motor is stopped in this situation, the
previous operating state of the electronic bypass package will be restored
by re-closing the fire alarm signal. It is recommended that VFD parameter
6.09, Catch a Spinning Motor, be set to 1 if the fire alarm input is used.
With the Fire Alarm (switch 2)
OFF
, the bypass will attempt to run the
system “to destruction” in the event of fire. Receiving a fire alarm signal in
this mode will force the unit to bypass, causing the motor to operate off the
AC line. The motor cannot be stopped locally or by external contacts in this
mode. The keypad will appear to be “locked out”. The previous operating
state of the bypass will be restored by re-closing the fire alarm signal
To restate, the Fire Alarm (switch 2)
ON
equals “All Stop” and
OFF
equals
“Purge”
Switch 3:
Used in damper applications where it is required to make sure a
damper has opened in order to run the motor. The default
ON
position of
Damper Control (switch 3) disables damper mode. With the damper mode
set in the enabled
OFF
position, when the motor is told to start (either on the
VFD or by the Bypass from the AC line) a 120 second timer is started. The