Specifications

DESCRIPTION AND OPERATION Document No. DER01120
Effective Date 25 May 07 Page 5 of 9
Figure 1120-3 Overload Release Assembly
FLUID COUPLING
The rotating assembly is driven by the 50 HP electric motor through the fluid coupling mounted on
the motor shaft. Rotary motion of the motor shaft is transmitted to the inner hub of the fluid
coupling. The outer hub of the coupling is connected to the sheave, which is rotated by the
pressure of fluid contained within the coupling. Since the sheave is coupled to the motor shaft by
a fluid coupling rather than a direct connection, the motor’s rotation is cushioned, permitting the
inertia of the rotating assembly to be overcome slowly, thereby allowing gradual, smooth
acceleration of the bowl.
ELECTRICAL CONTROL BOX
The centrifuge is turned on and off at the electrical control box (Figure 1120-4). Components in
the control box control operation of the 50 HP electric motor that drives the centrifuge rotating
assembly and slurry feed pump. Control box components also shut down the motor and feed
pump in case of an operational anomaly. The control box front panel contains an indicator that
maintains an ongoing count of the number of centrifuge operating hours.
The CENTRIFUGE ON/OFF and PUMP ON/OFF switches are also included on the front panel.
Each switch is split vertically, with the ON position at the left and OFF to the right. RESET buttons
are provided to permit manual resetting of the centrifuge and pump run relays following a trip.
Thermal overloads are built into the relays to shut down the centrifuge or feed pump motor in
case of excessive current draw. The button mechanically depresses a reset button on its
corresponding relay. Pressure switches shut down the feed pump when conveyor pressure
demand reaches 1500 PSI and re-start the feed pump when pressure falls to 700 PSI.