The Thermal Overload Protection Triggers; The Motor Becomes Excessively Hot; The Unit Runs But There Is Little Or No Flow Rate; When Switched Off, The Unit Turns In The Opposite Direction - Xylem LOWARA e-SV Series Additional Installation, Operation And Maintenance Instructions

7.5 The thermal overload protection triggers

The motor thermal overload protection triggers occasionally, or after the unit has been
running for a few minutes.
Cause
It is calibrated at a value too low in relation to the rated
current of the motor
Input voltage outside the rated limits
Unbalanced input voltage
Incorrect working curve (flow rate greater than the maximum
permitted flow rate)
Liquid too dense, presence of solid or fibrous substances
(unit overloaded)
Room temperature too high, exposure to sunlight
Unit faulty

7.6 The motor becomes excessively hot

Cause
Room temperature outside the rated limits
Cooling fan of the motor clogged or damaged
The unit starts up too frequently
The frequency converter, if present, has not been calibrated
properly

7.7 The unit runs but there is little or no flow rate

Cause
Motor turns in the wrong direction
Incorrect priming (there are air bubbles in the suction pipe or
in the unit)
Cavitation
Check valve locked in closed or partially closed position
Foot check valve locked in closed or partially closed position Replace the foot check valve
Discharge pipe throttled
Piping and/or unit clogged

7.8 When switched off, the unit turns in the opposite direction

Cause
Check valve faulty
Foot check valve faulty
2
Net Positive Suction Head
e-SV series – Additional Installation, Operation and Maintenance Instructions
en – Translation of the Original Instructions
Remedy
Recalibrate
Make sure the voltage values are correct
Make sure the voltage of the three phases is balanced
Reduce the required flow rate
• Reduce the density of the liquid and/or
• Remove the solid substances and/or
• Increase the size of the motor
• Lower the temperature at the point of the thermal
overload protection and/or
• Protect against direct sunlight
Send the unit to an authorised workshop for testing
Remedy
Lower the room temperature
Clean or replace the cooling fan
See the section: The unit produces excessive noise and/or
vibrations
See the frequency converter manual
Remedy
Check the direction of rotation and change it if necessary
Repeat the priming procedure
2
Increase the NPSH available in the system
Replace the check valve
Remove the throttling
Remove the clogging
Remedy
Replace the check valve
Replace the foot check valve
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