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860-7200-18 DTU DTB Service & Maintenance Manual
VFD: The VFD (Variable Frequency Drive) controls the conveyor
motors� One VFD controls the front conveyor and the other
controls the middle and rear conveyor motors (if equipped with a
powered 3rd conveyor)� The VFDs are located in the Drive panel�
The VFDs monitor each motor and will shut them o if a problem
is detected� The VFDs are connected to the safety mat circuit and
will shut the conveyor motors o if any safety mat is activated.
CONTROL DEVICES
Control Device: The PLC (Programmable Logic Controller) is
located on the inside of the Control Panel door� It controls most of
the functions of the machine. It processes many dierent inputs
and outputs connected to other components� It has expansion
input/output modules located next to it� There are LED indicators
on all components to show their status� The PLC is powered by
24VDC�
Drive Controls: The Destu-it can drive in either AC or DC mode.
There are two DC drive motors each connected to a gearbox and
Urethane drive wheel, located under the base of the machine�
They are accessible by removing the left and right oor plates. A
center mounted, swivel caster is located just behind the operator
platform� The drive motors are controlled by independent drive
boards and relays located on the inside of the drive panel door�
The drive boards and relays are controlled by the PLC� The PLC
sends a left and right speed signal to each respective drive board�
The relays enable the drive boards to move forward or cause it to
reverse the motor output polarity of one or both motors to control
direction of travel� The drive boards each have a power LED and
Fault LED� The drive boards can monitor circuit faults for voltage
or short circuit problems and overheating�
PLC (Programmable Logic Controller)
A
A
Drive Boards
VFDs
Drive Motor
NOTE: The Safety Mat reset must be performed each time the
machine is started in AC mode�
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