Operating instructions

MAINTENANCE
5-18 31 Dec 13
DE-7200VFDCentrifuge
TROUBLESHOOTING (CONT’D)
In case of control system malfunction, with electric power shut down, locked out, and tagged out
check that PLC connectors are fully seated in their receptacles. Correct as necessary before
proceeding with further troubleshooting.
Troubleshooting Chart
The troubleshooting chart consists of failure modes, possible cause(s), and recommended
course(s) of action. All electrical continuity checks in this procedure are performed without electric
power supplied to the centrifuge. Lock out and tag out equipment before attempting to perform any
continuity check.
WARNING! CONTINUITY CHECKS MUST BE PERFORMED WITHOUT
ELECTRIC POWER APPLIED TO CENTRIFUGE. LOCK OUT AND TAG OUT
ELECTRIC POWER BEFORE ATTEMPTING CONTINUITY CHECKS.
In addition to the troubleshooting information, the technician should refer to the schematic diagrams
at the rear of this section and to the appropriate schematic and wiring diagrams in Section 8 and
description and theory of operation in Section 1 for additional assistance in troubleshooting.
TROUBLESHOOTING DE-7200 VFD CENTRIFUGE
Possible Cause Isolation Procedure & Corrective Action
Failure Mode 1: Acceptable Liquid, Cake Too Thin
Insufficient solids in feed Increase weir opening (refer to Section 4).
Reduce differential speed.
Drop in feed pump rate Increase feed rate.
Check feed pump; if required, check wear and replace worn
parts.
Check pump shaft seal, and correct any defects.
Select RESET on Fault Reset screen to reset flow rate.
Failure Mode 2: Poor Liquid Quality, Acceptable Cake
Bowl speed too low Increase bowl speed.
Reduce feed rate.
Excessive amount of solids in
feed
Reduce quantity of solids in feed or add dilution stream if
possible.
Change in feed characteristics Reduce quantity of solids in feed or generally optimize
machines settings, i.e. adjust bowl speed, differential speed,
and weir opening.
Conveyor flights worn
excessively
Measure clearance through inspection port (Figure 5-9).
Replace rotating assembly if excessive wear is found (refer to
Rotating Assembly maintenance).