Extreme Running Conditions; Acoustic Noise - Danfoss FCM 300 Series Design Manual

Extreme running conditions

Motor-generated overvoltage
The voltage in the intermediate circuit is increased
when the motor acts as a generator. This occurs in
two cases:
1. The load drives the motor (at constant output
frequency from the frequency converter), i.e. the
load generates energy.
2. During deceleration ("ramp-down") if the
moment of inertia is high, the load is low and
the ramp-down time is too short for the energy
to be dissipated as a loss in the VLT frequency
converter, the motor and the installation.
The control unit attempts to correct the ramp if
possible.
The inverter turns off to protect the transistors and
the intermediate circuit capacitors when a certain
voltage level is reached.
Mains drop-out
During a mains drop-out, FCM 300 Series continues
until the intermediate circuit voltage drops below the
minimum stop level, which is typically 15% below
FCM 300 Series's lowest rated supply voltage.
The time before the inverter stops depends on the
mains voltage before the drop-out and on the motor
load.
Static overload
When FCM 300 Series is overloaded (the current
limit in parameter 221 has been reached), the
controls will reduce the output frequency in an
attempt to reduce the load.
If the overload is excessive, a current may occur that
makes the FC motor cut out after approx. 1.5 sec.
MG.03.B6.02 - VLT is a registered Danfoss trademark
FCM 300 Series

Acoustic noise

Below are the typical values measured at a distance
of 1 m from the unit at full load:
2 pole
FCM 305
FCM 311
FCM 315
FCM 322
FCM 330
FCM 340 62 dB(A)
FCM 355 64 dB(A)
FCM 375
Balance
The FCM 300 is balanced to class R according to
ISO2373 (reduced balance). For critical applications
especially at high speed (>4000 RPM) special
balance (class S) might be required.
4 pole
54 dB(A)
58 dB(A)
59 dB(A)
58 dB(A)
61 dB(A)
63 dB(A)
60 dB(A)
61 dB(A)
85