Specifications

Document No. DER04097 OPERATING INSTRUCTIONS
Page 6 of 7 Effective Date 27 Nov 07
Overload Release Clutch Torque
Frequent overload tripping that cannot be corrected by feed rate and/or pond depth adjustments
may be due to an incorrect torque setting of the overload release assembly. To check and adjust
overload release assembly torque, refer to
DER05104.
AUTOMATIC SHUTDOWNS
The centrifuge has built-in safety features to protect the equipment. These features will result in
automatic shutdown of the centrifuge before damage occurs. The following paragraphs describe
these automatic shutdowns.
Excessive Vibration
A vibration level of 2 Gs will cause the vibration switch to interrupt electric power to the centrifuge
run relay, shutting down the machine. Such excessive vibration may occur during startup or
normal operation due to slumping of the wall cake or other unbalanced condition of the bowl. The
machine may be re-started by pressing the reset button on the vibration switch and then using the
Normal Startup procedure above.
If nuisance tripping occurs during normal startup, the reset button may be held depressed until full
speed is reached.
Motor Thermal Overload
Thermal overloads protect the circuits supplying electric power to the 50 HP centrifuge drive
motor and feed pump motor. In case of excessive current draw through the centrifuge motor
starter circuit, the thermal overload trips to disable the centrifuge run relay and shut down the
motor. Excessive current draw through the pump starter circuit trips the thermal overload, which
de-energizes the pump start relay to disable the feed pump motor. To re-start the centrifuge
following shutdown due to a thermal overload trip, clear the cause of excessive current draw,
press both RESET buttons, and then re-start the machine using the Normal Startup procedure
above.
Motor Over-Temperature
If high temperature is sensed by the thermocouple embedded in the 50 HP motor winding, the
motor over-temperature switch in the motor winding opens, disabling the centrifuge run relay and
shutting down the motor. To re-start the centrifuge, allow the motor to cool, check for and remove
the cause of over-temperature, and then re-start the machine using the Normal Startup procedure
above.
Conveyor Over-Torque
If excessive torque is required to rotate the conveyor (335 in lbs for 52:1 gearbox; 200 in lbs for
125:1 gearbox), the overload clutch releases the conveyor from rotating and the over-torque limit
switch shuts down electric power to the centrifuge and feed pump. The normally closed over-
torque limit switch contacts are opened by the release roller arm, interrupting power to the 50 HP
drive motor and feed pump motor. After release, the clutch must be manually reset (refer to
Section 5 - Maintenance) before the centrifuge can be returned to operation.