Danfoss VLT FC 103 Operating Instructions Manual page 69

Basic Troubleshooting
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Acoustic noise or vibration
(e.g. a fan blade is making
noise or vibrations at
certain frequencies)
Table 9.1 Troubleshooting
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VLT Refrigeration Drive Operating Instructions
Possible cause
Resonances, e.g. in the motor/fan
system
MG16J102 - VLT is a registered Danfoss trademark
Test
Bypass critical frequencies by using
parameters in parameter group
4-6* Speed Bypass
Turn off over-modulation in
14-03 Overmodulation
Change switching pattern and
frequency in parameter group
14-0* Inverter Switching
Increase Resonance Dampening in
1-64 Resonance Dampening
Solution
Check if noise and/or vibration
have been reduced to an
acceptable limit
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