Specifications

OPERATING INSTRUCTIONS Document No. DER04098

Effective Date 06 Jun 08 Page 19 of 19

Excessive Vibration

Excessive vibration of the centrifuge 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.

Main Bearing Temperatures

Temperature sensors are installed on the liquid and solid end main bearings and connected to the

PLC. Bearing temperatures are continuously displayed on the Operation screen. An alarm

message is displayed on the control panel when bearing temperature exceeds 225°F (107°C). If

temperature rises to 250°F (120°C), a fault message appears and the centrifuge is shut down.

Excessively high bearing temperatures usually indicate bearing failure, which can result from

inadequate lubrication, contamination, or normal wear. Refer to

DER05024 for main bearing

replacement procedure.

Note: Both main bearings should be replaced if centrifuge has shut down due

to high main bearing temperature.

Excessive Bowl Speed

A sensor that detects the rotating speed of the bowl provides an input to the PLC that produces a

continuous display of actual bowl speed on the Operation and VFD screens. If the bowl speed

exceeds 3050 RPM, the bowl speed sensor provides an input to the PLC causing an alarm

message to be displayed on the control panel. A fault message is displayed and the centrifuge is

immediately shut down if speed rises to 3100 RPM. To re-start the centrifuge, allow the bowl to

coast to a complete stop, check for and remove the cause of excessive speed. With bowl at a

complete stop, check speed sensor as follows:

1. Check speed sensor connections.

2. With bowl at a complete stop, check for a zero bowl speed reading on bowl VFD screen

(Figure 4098-10). A reading of “0” indicates no defects in sensor and connection. If reading is

greater than 3250 RPM, check sensor and/or connection.

3. Replace sensor if defective, and/or repair damaged connection.

4. After correcting any defect(s), re-start the machine using the Normal Startup procedure above,

and re-check bowl speed.

The content of this document is subject to change at any time. Information provided does not cover all details or variations possible

with DERRICK equipment; nor does it cover every contingency that may be met during installation, operation, maintenance, or

troubleshooting of the equipment. If additional information is required, or should situations arise that are not covered by this manual,

bring the matter to the attention of your local DERRICK representative or the Service Department at DERRICK Corporation in

Buffalo, New York.