Specifications

OPERATING INSTRUCTIONS Document No. DER04098
Effective Date 06 Jun 08 Page 15 of 19
Both the conveyor speed setting and actual conveyor speed are shown on the control panel. In
addition, the conveyor torque percentage is shown to assist in optimizing conveyor speed to
produce the desired solids dryness and processing speed.
Since the conveyor differential speed is controlled by the PLC relative to the bowl speed setting,
wiring polarity of electrical components is critical. The effects of electrical polarity on differential
speed can be learned from the Conveyor Motor Speed chart in Section 11, which can be used to
determine actual speed and direction of conveyor motor for any bowl speed setting. For example,
with a bowl speed setting of 2000 RPM and conveyor differential speed set at 60, the conveyor
motor will rotate in reverse at -1120 RPM.
The correct bowl-conveyor speed relationship depends on correct wiring polarity. If polarity is
reversed, the same bowl speed setting of 2000 RPM described above would result in an actual
conveyor differential speed of about 17 rather than the setting of 60.
The following equations can be used to determine the conveyor differential speed or actual
conveyor motor speed.
To determine conveyor motor speed when bowl speed and conveyor differential speed (Δ) setting
are known:
(
)
RatioGearboxxSpeedBowlSpeedMotorConveyor
Δ
=
To determine actual differential speed when bowl speed and conveyor motor speed are known:
RatioGearbox
SpeedMotorConveyorSpeedBowl −
=Δ
Pond Depth
Six adjustable effluent ports (Figure 4098-16) are provided on the liquid bowl head to facilitate
setting the pond depth; all ports must be set identically. A deeper pond reduces the beach area at
the solids discharge end of the bowl, which typically results in a wetter solids discharge.
Conversely, setting the pond at a more shallow depth increases the beach area, thus producing
drier solids discharge.
Pond depth can only be adjusted with the centrifuge fully stopped and disabled. For this reason,
pond depth is usually adjusted last. The factory pond depth setting is usually satisfactory when
used in conjunction with feed rate, bowl speed, and conveyor speed adjustments. However, if
desired results cannot be achieved by other means, the pond depth may require re-setting.
To adjust pond depth, proceed as follows:
WARNING! DO NOT OPEN COVER OR ATTEMPT ADJUSTMENT OR
MAINTENANCE ON THE CENTRIFUGE UNLESS THE BOWL IS
COMPLETELY STOPPED.
1. Shut down, lock out, and tag out the centrifuge using the Normal Shutdown procedure
described later in this section.
2. Remove access plate from the inlet side of the case cover.
3. Loosen screws securing the weir plates, move the weir plates to the required weir opening
size, and re-tighten screws to torque specified in
DER05029.