16
selections and force the Electronic bypass into bypass mode from an
external contact. Once this signal is removed, the Electronic bypass will
not return to its’ previous mode of operation without keypad interaction.
Remote VFD input (TB3-2): works just like the remote bypass input, by
forcing the Electronic bypass into VFD mode. The Electronic bypass will not
return to its previous mode when the signal is removed.
3.5 Alarm Displays
The safety, fire, and VFD alarms have already been covered. The fourth
alarm is motor overload, which is generated by the overload relay built into
the Electronic bypass. Should this relay operate, the motor will stop
independent of its mode of operation. The motor can not be restarted
while the motor overload indicator is illuminated. Once the relay is reset,
operation can be restored by reselecting a run mode from the keypad.
3.6 Failure and Power Off Conditions
Should the Electronic bypass control card fail such that it can not process
inputs, the control card has an alternative mechanism for controlling the
bypass contactors. Jumpers J5, J6, and J7 control the input, bypass, and
output contactors respectively. Moving any of these jumpers from the
default “open” position to the “emergency” position will force the associated
contactor to be energized. This will happen irrespective to any logic
damage on the bypass board. See section
3.8.3 for details.
In the event the bypass control board should lose power, its EEPROM
memory retains the last operating configuration, which is restored on the
next power up.
3.7 Control Modes of the Electronic bypass
When power is initially applied, the green main Power ON LED is
illuminated and will remain on as long as power is connected. The
OFF/RESET will be the only other LED illuminated. The input contactor
remains in the off position. The VFD will have no power and its display will
remain blank. An operation mode must first be selected, followed by the
start mode selection.
3.7.1 TEST mode
In TEST mode the functionality of the VFD, external speed reference
devices, and system setup characteristics can be read, set and modified. In
TEST mode the input contactor is energized. Note that the TEST mode and
BYPASS mode can be operated simultaneously, if desired.
To place the VFD package in TEST mode, press the TEST button. The
TEST and input contactor LEDs will be illuminated.
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