VLT
®
FCM Series
■
Forced ventilation (FV) units (Not yet available)
In some applications the fan built on to the motor
shaft do not give sufficient cooling for operation at low
speed. That problem is solved by mounting a FV unit.
Typical applications are for example conveyors,
spindles and other contant torque (CT) applications
where the customer wants a wide control range without
reduction in torque down to low speed.
The VLT Drive Motor yields full continuous torque
down to low speed with FV built on. The forced vent
enclosure is IP 55. Not approved according to UL.
■
FCM 300 Thermal Protection
The thermal protection of FC and motor is
covered in the following way:
1. Overload situations are handled by the calculated
electrical load (I
2
X t).
2. Missing ventillation and high ambient temperature
is handled by the temperature measurement. The
derating for low speed (due to missing ventillation)
is not incoporated in the electrical load calculaton
but taken care of by the temperature measurement.
Forced ventillation is thus automaticly covered.
Electrical load
The current is measured in the DC link and the
estimated load is calculated. The level of the electrical
load is set at an output torque of 105%. Above
that level a counter is increased, below the level it
is decreased. The counter starts at zero. When the
counter reaches 100, the unit trips. At 98 the warning
indication goes on (LED and status word).
Load
Time from 0 to 100
Time from 100 to 0
0%
-
60 sec
20%
-
100 sec
40%
-
150 sec
60%
-
200 sec
80%
-
250 sec
105%
900 sec (if over 105%)
300 sec (if under 105%)
120%
550 sec
-
140%
210 sec
-
160%
60 sec
-
>165% 20 sec
-
At full AC brake (parameter 400) a load > 165%
is simulated => 20 sec to trip.
The value can be read in parameter 527.
(LCP:FC thermal)..
Temperature measurement
The temperature measurement is sensing the
temperature within the electronics box.
’
At warning level => Warning indication goes on
(LED and status word) and the unit might trip if the
temperature doesn
’
t sink back below warning level
within 15 minutes. If the function TEMP.DEP.SW is
activated in parameter 412, the switching frequency
is decreased gradually down to 2 kHz attempting
to decrease the temperature.
Trip level => Immediate trip and alarm indication
(LED and status word).
The value can be read in parameter 537
(LCP: Heat sink temp.).
The temperature levels seem to be high, but due to a
local heating of the sensor the practical levels of the
inside air temperature are approx. 10 deg C lower.
MG.03.H3.02 - VLT is a registered Danfoss trademark
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