Appendix; Operation With Variable Frequency Drives - Wilo Rexa PRO Serie Instrucciones De Instalación Y Funcionamiento

US English
2. Slide valve in the pressure pipe is closed
• Open the slide valve completely
3. Impeller blocked or slowed
• Switch off pump, secure it against being switched
back on again, and free the impeller
4. Incorrect direction of rotation
• Swap two phases of the power supply
5. Air in the system
• Check the pipelines, pressure shroud, and/or
hydraulics, and vent if necessary
6. Pump pumping against excessive pressure
• Check the slide valve in the pressure pipe and
open it completely if necessary; use a different
impeller; consult the manufacturer
7. Signs of wear
• Replace worn parts
8. Faulty hose/piping
• Replace faulty parts
9. Inadmissible levels of gas in the fluid
• Consult the manufacturer
10. Two-phase operation
• Have a specialist inspect the connection and
correct it as necessary
11. Excessive decrease in the water table during oper-
ation
• Check the supply and capacity of the system, and
inspect the level control settings and function-
ality
Fault: the unit does not run smoothly and is noisy
1. Pump is operating in an inadmissible range
• Check the operational data of the pump and
correct if necessary and/or adjust the operating
conditions
2. Suction port, suction strainer, and/or impeller
clogged
• Clean the suction port, suction strainer, and/or
impeller
3. Impeller stiff
• Switch off pump, secure it against being switched
back on again, and free the impeller
4. Inadmissible levels of gas in the fluid
• Consult the manufacturer
5. Two-phase operation
• Have a specialist inspect the connection and
correct it as necessary
6. Incorrect direction of rotation
• Swap two phases of the power supply
7. Signs of wear
• Replace worn parts
8. Defective motor bearing
• Consult the manufacturer
9. Pump is installed under tension
• Check installation, use rubber expansion joints if
necessary
28
Fault: mechanical seal leak, sealing chamber con-
trol reports a fault or switches the unit off
1. Condensation build-up due to extended storage
and/or high temperature fluctuations
• Operate the pump briefly (max. 5 min.) without
pencil electrode
2. Increased leakage when running in new mechanical
seals
• Change the oil
3. Defective pencil electrode cable
• Replace pencil electrode
4. Mechanical seal is defective
• Replace the mechanical seal; consult the manu-
facturer!
Further steps for troubleshooting
If the points listed here do not rectify the fault,
contact Wilo customer service, who can assist you
further as follows:
• Telephone or written support from Wilo customer
service
• On-site support from Wilo customer service
• Inspection or repair of the pump at the factory
Please note that you may be charged for some
services provided by our customer service. For more
details, please contact Wilo customer service.

10. Appendix

10.1. Operation with variable frequency drives

Any standard motor can be used, subject to com-
pliance with IEC 60034-17. If the rated voltage
is above 415 V/50 Hz or 480 V/60 Hz, you must
consult the manufacturer. Because of the addition-
al heating caused by harmonics, the rated power
of the motor should be around 10% more than
the power requirement of the pump. For variable
frequency drives with low harmonic output, it may
be possible to reduce the 10% power buffer. This
is normally done by using output filters. Further-
more, the standard motors are not equipped with
shielded cables. The variable frequency drive and
filter must be synchronized with each other. Ask the
manufacturer.
The configuration of the variable frequency drive
depends on the rated motor current. Make sure
that the pump operates without jerking or vibrat-
ing, especially in the lower speed range. Otherwise,
the mechanical shaft seals could be damaged and
start leaking. Also consider the flow rate in the
pipe. The slower the flow rate, the greater the risk
of solids depositing in the pump and piping. We
therefore recommend a minimum flow rate of
2.3 ft/s (0.7 m/s) at a pumping pressure of 5.8 psi
(0.4 bar).
It is important that the pump operates across the
entire control range without vibrations, resonance,
oscillation, or excessive noise (consult the manufac-
APPENDIX
WILO SE 2014-11 V05 Letter