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13
Appendix
13.1
Tightening torques
13.2
Frequency converter operation
44
Appendix
Rust-free screws A2/A4
Thread
Tightening torque
Nm
M5
5.5
M6
7.5
M8
18.5
M10
37
M12
57
M16
135
M20
230
M24
285
M27
415
M30
565
If a Nord-Lock screw locking device is used, then increase the tightening torque by 10 %!
The motor in series design (conforming to IEC 60034‑17) can be operated with a frequency
converter. Contact customer service if the rated voltage is above 415 V/50 Hz or
480 V/60 Hz. Because of the additional heating caused by harmonics, the rated power of the
motor should be around 10 % more than the power requirement of the mixer. For frequency
converters with a low-harmonic output, it is possible to reduce the 10 % power reserve.
Harmonic waves are reduced by means of output filters. Synchronize the frequency con-
verter and the filter with each other!
The configuration of the frequency converter depends on the rated motor current. Make
sure that the mixer operates across the entire control range without jerking or vibrating
(without vibrations, resonance, oscillation). Otherwise, the mechanical seals may leak or be
damaged. Increased motor noise caused by the harmonics of the power supply is normal.
During parameterisation of the frequency converter, observe the setting of the quadratic
curve (U/f curve) for submersible motors! The U/f curve ensures that the output voltage at
frequencies less than the rated frequency (50 Hz or 60 Hz) is adjusted to the power require-
ment of the mixer. More recent frequency converters feature an automatic power optimiza-
tion function - this automation achieves the same effect. For the frequency converter set-
ting, refer to the installation and operating instructions of the frequency converter.
Motor monitoring faults may occur if the motor is operated with a frequency converter. The
following measures can reduce or avoid these faults:
ƒ
Keeping within the limit values stated in IEC 60034‑25 for overvoltage and rise speed. If
necessary, install output filters.
ƒ
Vary the pulse frequency of the frequency converter.
ƒ
In the event of a fault in the internal sealing chamber monitoring, use the external dou-
ble-rod electrode.
The following construction measures can help to reduce or prevent faults:
ƒ
Separate connection cables for the main and control cable (depending on the motor size).
ƒ
Keep an adequate distance between main and control cable during routing.
ƒ
Use shielded connection cables.
kp m
ft·lb
0.56
4
0.76
5.5
1.89
13.5
3.77
27.5
5.81
42
13.77
100
23.45
170
29.06
210
42.31
306
57.61
417
WILO SE 2021-10
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