Faults, Causes And Remedies - Wilo MMI50V Instrucciones De Instalación Y Funcionamiento

10 FAULTS, CAUSES AND REMEDIES

Fault Cause
- Head loss too high
- Pump suction not flooded
- NPSH available to low
The pump is not
- Wrong direction of rotation
producing the rated
flow or head
- Leakage on discharge flange gasket
- Level probe set too deep
- Motor speed too low
- Worn impeller
- Liquid cannot reach pump inlet
- Foreign material in the pump
Poor pump suction
- Liquid level to low in the pit
- Intermediate shaft bearing worn
Liquid flows out
- Discharge opening clogged
through upper
opening in the
- Liquid level too high
column
- Impeller unballanced
- Ball bearing destroyed
High vibration level
- lack of grease in bearing bracket type TM
- Worn intermediate shaft bearing
Temperature of - Destroyed ball bearing in bearing bracket
bearing bracket
- Worn ball bearing in bearing bracket or motor
increases
- Pump suction not flooded
- Suction head too high or discharge head too low
- Pump not properly leveled or base plate is
Pump runs noisily
distorted.
- Excessive forces applied on discharge flange
- Foreign matter in the pump casing
- Current leakage
- Circuit breaker rating too low
- Liquid specific gravity or viscosity is higher than
Motor protection
expected
switches off
- Pump runs right of curve or out of application
limits
- Foreign material in the pump
Remedy
Check head losses on discharge line
Check valves are open and setting of SRV or flow control valves
Check clogging level of strainer.
Remove pump from pit and clean the strainer
Check wear on the impeller
Check % of particle content in the fluid
Check fluid levels, temperature and fluid vapor pressure
Change two phases in motor junction box
Check tightening of flanges fastening bolts and state of the gasket
Set minimum level higher in order to have a minimum fluid level
above pump back cover
Check motor electric connection
Check frequency on VSD
Check fluid characteristics
Replace impeller
Clean the strainer
Check that available NPSH of the process is higher than the pump
required NPSH
Open and clean pump casing
Check wear on the impeller
Check setting depth of low level and low low level sensors.
Check pump stops on low level.
Register low level value
Dismantle and check wear of the bearing
Lift the pump out of the pit and clean pump column. Open
discharge opening
Check setting of high level sensor
Check fluid inflow
Dismantle the impeller and check there's no foreign matter stuck
between vanes
Check impeller is not clogged or worn
Dismantle pump and replace ball bearing.
Check there's no liquid inside the bearing bracket housing
Fill in the greaser or tight it
Check a maintenance schedule exists and is respected.
Check that the bearing lubrication circuit is OK
Replace the bearing
Replace the ball bearing
Identify and replace worn ball bearing
Check for sign of cavitation
Check that pump stops on low level and that strainer is not clogged
Check lower liquid level (if suction extension pipe is used)
Clean the strainer
Check that available NPSH of the process is higher than the pump
required NPSH
Check that pump is correctly installed on pit horizontal without any
distortion.
Check there's no mechanical constrains applied on pump parts in
the pit and on the discharge pipe.
Open and clean the casing
Check motor earthing
Find out the origin of the current leakage : damaged cables, fluid
leakage on electrical components, ...
Check motor nominal current and select motor proper protection
according In
Change motor to increase installed power
Measure pump duty point and check that pump runs in the
authorized application limits
Open and clean the casing
ENGLISH
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