VLT
®
FCM Series
All about FCM
300
■ Thermal Protection and Derating
The FCM 300 Series motor is thermally protected in
case limits are exceeded. At high temperatures the
switching frequency will be gradually reduced down
to 2 kHz and eventually the motor will trip.
NB!:
Combination of high switching frequency and
missing fan cooling might damage the unit.
■ Derating for ambient temperature
The ambient temperature (T
AMB,MAX
) is the maximum
temperature allowed. The average (T
AMB,AVG
) measured
over 24 hours must be at least 5ºC lower.
If FCM 300 Series is operated at temperatures
above 40 ºC, a derating of the continuous
output current is necessary.
■ Derating for air pressure
Below 1000 m altitude no derating is necessary.
Above 1000 m the ambient temperature (T
AMB
)or
max. output current (I
VLT,MAX
) must be derated in
accordance with the following diagram:
1. Derating of output current versus altitude
at T
AMB
=max. 40°C
2. Derating of max. T
AMB
versus altitude at
100% output current.
■ Derating for running at low speed
When a centrifugal pump or a fan is controlled
by a FC motor, it is not necessary to reduce the
output at low speed because the load characterstic
of the centrifugal pumps/fans, automatically
ensures the necessary reduction.
FC motors running constant load torque applications
continuously at low speed must be derated (see
diagram) or an independent fan must be used
(cooling option 2, not yet available).
Nominal torque (100%) can be yielded up to 15 min
and at a duty cycle up to 25% at low speed.
■ Derating for high switching frequency
The FCM 300 Series motor can use two different
PWM schemes, SFAVM and 60° AVM. Factory setting
is SFAVM. The PWM scheme can be changed in
parameter 446. Below 25 Hz motor speed the FCM
300 Series motor automatically change to SFAVM.
Factory setting of the switching frequency is
4000 Hz. It can be changed between 2 and
14 kHz in parameter 411.
MG.03.H3.02 - VLT is a registered Danfoss trademark
89
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