ABB DCS 400, Manual

Page: 55 / 192

II K 4-31
Overview of Software
Without speed-dependent current limiting
The field weakening mode is selected or not selected
as a function of the parameter values Base Speed
(1.05) and Max Speed (1.06):
no field weakening:
If the contents of Base Speed (1.05) is identical
with Max Speed (1.06)
field weakening:
If the contents of Base Speed (1.05) is smaller
than Max Speed (1.05)
In the case of manual parameterization and no field
weakening set both parameters to identical values.
With field weakening: set the Base Speed to the
nominal speed at nominal armature voltage and Max
Speed to the maximum speed at maximum field
weakening. If you parameterize the converter with
the prompted start-up procedure (Panel Wizard) the
parameters will be interrogated during entry and will
be set appropriately.
Field weakening is possible only with a tacho-gener-
ator or encoder feedback. If the EMF feedback is
used the motor can be run only up to the nominal
speed Base Speed (1.05). Higher reference values
will not cause any increase in speed, there will be no
field weakening.
With speed-dependent current limiting
Beyond the normal field weakening range, the arma-
ture current of a motor must be reduced because of
the commutation problems to be expected. This speed
is the maximum electrical speed of a motor. Set the
parameter Cur Lim Speed (1.12) to the speed, from
which the limitation shall be effective, for this speed
dependent current limiting. Within the speed range
between Cur Lim Speed (1.12) and Max Speed (1.06)
the permissible armature current Cur Arm Max (3.04)
is reduced to Ia
Lim
as a function of speed according to
the following formula:
Ia
Lim
= Arm Cur Max * (Cur Lim Speed / Speed Act)
n
P
Base
Speed
Max
Speed
Cur Lim
Speed
speed dependent
current limiting
I
aLim
effective
(1.05) (1.06) (1.12)
4.5.4 Overtemperature Protection
Converter:
DCS400 is equipped with an overtemperature protec-
tion on the heat sinks of the thyristors. When the
maximum bridge temperature is reached DCS400
switches off with the fault message Converter Over-
temp (F7). The converter can be switched on again
only after sufficient cooling and acknowledgement of
the fault. 5 °C below the cut-out temperature the
warning Converter High Temp (A4) is output but the
drive is not switched off.
In case of overheating the Fan On signal will be active
(fan coasting) until the converter has cooled down.
The signal can be evaluated by means of the digital
outputs DO1…DO5.
Motor:
The temperature protection of the motor can be
evaluated via a PTC element (usually in the field or
commutating winding of the motor) in the DCS400.
For this purpose the PTC element shall be connected
to the AI2 analog input. The response of the DCS400
when the temperature monitor trips is set with the
parameter PTC Mode (2.12).
The tripping of the temperature monitor of the motor
has the same effect on the Fan ON signal as the
converter temperature monitor: The signal remains
present until the motor temperature has decreased
sufficiently.
PTC connection diagram:
100k
1n
1n
100k
100k 100k
+10V
S1:
-
+
22 K
4
X2:3
5 6 PTC
5
AI2
GND