Electronic Bypass Controller Installation and Commissioning Guide
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“damper feedback” contact closed (TB3-3) within that time to prevent the bypass
controller from “faulting” and preventing motor operation. The bypass keypad will
annunciate the faulted condition by flashing one or more of the button status LEDs
that happened to be on at the time of the fault. The bypass controller can be reset
by cycling the customer reset input, which will reset the 120 second timer and retry
motor operation.
Should the damper open initially, but sometime during operation the damper
feedback is lost, the electronic bypass package will trip, stopping the motor.
Switch 4:
With the VFD and AUTO pushbuttons pressed on the bypass keypad, Fire
Alarm (switch 2) and Fireman’s Override (switch 4) OFF, upon opening the fire alarm
input (TB2-6) the unit goes into Bypass Mode and the bypass keypad will indicate a Fire
Alarm. A VFD fault will occur and the input contactor will drop out.
Upon closing the fireman’s override input (TB3-4), the unit will go to Bypass and Hand
Mode.
Re-closing the fire alarm input and then opening the fireman’s override input (TB3-4)
will put the package back into VFD + Auto Mode.
With Damper Control (switch 3) OFF
: For normal operation mode, a start command
is given, closing the Damper relay contacts. The unit then waits for a contact closure
from the customer-supplied Damper End switch indicating the damper is fully open.
If the damper feedback does not occur within 120 seconds, then one or more of the
LEDs on the board will begin to flash indicating the Damper Close Timer has timed out
without feedback being received.
In Fireman’s Override Mode, if the fireman’s override is enabled along with the
Damper Control, at the end of the 120 seconds if there is no feedback from the
Damper End switch, the unit goes into bypass and operates as described above.
4.4 Using the Additional Customer Inputs
In addition to the inputs described in the preceding sections, there are three other
customer inputs for use in specific applications.
Safety input (TB2-3)
: is normally closed. Opening it causes the motor to stop
under all conditions and will lock out all requests to start the motor. A LED in the
Alarm Display annunciates the status of the safety input. If there are no safeties, a
jumper must be installed between TB-s-3 and TB-2-8 to allow operation. To reset the
electronic bypass package from a safety trip, the safety interlock must be re-closed
and the customer reset input (TB2-4) or the bypass keypad OFF/RESET button must
be cycled.
