4.5 Special Functions
400
Brake function
Value:
Off (off)
[0]
Resistor brake
(Resistor)
[1]
AC brake (AC Brake)
[4]
Load sharing (load sharing)
[5]
Factory setting depends on unit type.
Function:
[1] Resistor brake
is selected if the adjustable frequency
drive has an integral brake transistor and brake resistor is
connected to terminals 81, 82. A higher intermediate
circuit voltage is permitted during braking (generated
operation) when a brake resistor is connected.
[4] AC brake
can be selected to improve braking without
using brake resistors. Note that
[4] AC brake
is not as
effective as
[1] Resistor brake
.
Description of choice:
Select
[1] Resistor brake
if a brake resistor is connected.
Select
[4] AC brake
if short-term generated loads occur. See
parameter 144 Gain AC brake
to set the brake.
Select
[5] Load sharing
if this is used.
NOTICE
A change of selection does not become active until the
mains voltage has been disconnected and reconnected.
405
Reset function
Value:
Manual reset (manual reset)
[0]
Automatic reset x 1
(AUTOMATIC x 1)
[1]
Automatic reset x 3
(AUTOMATIC x 3)
[3]
Automatic reset x 10
(AUTOMATIC x 10)
[10]
Reset at power-up
(RESET AT POWER UP)
[11]
Function:
Select whether reset and restart after a trip are to be
manual, or whether the adjustable frequency drive is to be
reset and restarted automatically. Furthermore, it is
possible to select the number of times a restart is to be
attempted. The time between each attempt is set in
parameter 406 Automatic restart time
.
Description of choice:
If
[0] Manual reset
is selected, reset is to be carried out via
the [STOP/RESET] key, a digital input or serial communi-
cation. If the adjustable frequency drive is to carry out an
automatic reset and restart after a trip, select data value
[1]
Automatic reset x 1, [3] Automatic reset x 3 or [10] Automatic
reset x 10
.
If
[11] Reset at power-up
is selected, the adjustable
frequency drive carries out a reset if there has been a fault
in connection with the mains failure.
WARNING
The motor may start without warning.
406
Automatic restart time
Value:
0 - 1800
5
Function:
This parameter allows setting of the time from tripping
until the automatic reset function begins. It is assumed
that automatic reset has been selected in
parameter 405
Reset function
.
Description of choice:
Set the required time.
409
Trip delay overcurrent, I
LIM
Value:
0 - 60 (61=OFF)
OFF
Function:
When the adjustable frequency drive registers that the
output current has reached the current limit I
LIM
(
parameter
221 Current limit
) and remains there for the preset time, it
is disconnected. Can be used to protect the application,
like the ETR protects the motor if selected.
Description of choice:
Select how long the adjustable frequency drive should
maintain the output current at the current limit I
LIM
before
it disconnects. At OFF,
parameter 409 Trip delay overcurrent,
I
LIM
is not working, i.e. disconnection does not take place.
411
Switching frequency
Value:
3000 - 14000 Hz (VLT 2803 - 2875)
4500 Hz
3000 - 10000 Hz (VLT 2880 - 2882)
4500 Hz
Function:
The set value determines the switching frequency of the
inverter. If the switching frequency is changed, this may
help to minimise possible acoustic noise from the motor.
Description of choice:
When the motor is running, the switching frequency is
adjusted in
parameter 411 Switching frequency
until the
frequency has been obtained at which the motor is as low-
noise as possible.
WARNING
The output frequency of the adjustable frequency drive
can never assume a value higher than 1/10 of the
switching frequency.
Programming
Design Guide
92
Danfoss A/S © Rev. May/2014 All rights reserved.
MG27E402
4
4
