VLT
®
5000 Series
If a high torque characteristic is chosen, a rated mo-
tor with the VLT frequency converter obtains up to
160% torque for 1 min. in both CT and VT. If a nor-
mal torque characteristic is chosen, an oversize
motor allows up to 110% torque performance for up
to 1 min. in both CT and VT. This function is used
mainly for pumps and fans, since these applications
do not require an overload torque.
The advantage of choosing a normal torque charac-
teristic for an oversize motor is that the VLT
frequency converter will be able constantly to yield
100% torque, without derating as a result of a bigger
motor.
NB!:
This function c
annot
be chosen for VLT 5001-
5006, 200-240 Volts, and VLT 5001-5011,
380-500 Volts.
■ Internal current regulator
The VLT 5000 features an integral current limit regu-
lator which is activated when the motor current, and
thus the torque, is higher than the torque limits set in
parameters 221 and 222.
When VLT 5000 Series is at the current limit during
motor operation or regenerative operation, the VLT
frequency converter will try to get below the preset
torque limits as quickly as possible without losing
control of the motor.
While the current regulator is active, the VLT fre-
quency converter can only be stopped by means of
terminal 27 if set to Coasting stop, inverse [0] or Re-
set and coasting stop, inverse [1]. A signal on
terminals 16-33 will not be active until the VLT fre-
quency converter has moved away from the current
limit.
Please note that the motor will not use the ramp-
down time, since terminal 27 must be programmed
for Coasting stop, inverse [0] or Reset and coasting
stop, inverse [1].
■ Programming of Torque limit and stop
In applications with an external electro-mechanical
brake, such as hoisting applications, it is possible to
stop the VLT frequency converter via a ‘standard’
stop command, while at the same time activating the
external electro-mechanical brake.
The example given below illustrates the program-
ming of VLT frequency converter connections.
The external brake can be connected to relay 01 or
04, see Control of mechanical brake on page 66.
Program terminal 27 to Coasting stop, inverse [0] or
Reset and coasting stop, inverse [1], as well as ter-
minal 42 to Torque limit and stop [27].
D
escription:
If a stop command is active via terminal 18 and the
VLT frequency converter is not at the torque limit,
the motor will ramp down to 0 Hz.
If the VLT frequency converter is at the torque limit
and a stop command is activated, terminal 42 Output
(programmed to Torque limit and stop [27]) will be
activated. The signal to terminal 27 will change from
’logic 1’ to ’logic 0’ and the motor will start coasting.
- Start/stop via terminal 18.
Parameter 302 = Start [1].
- Quickstop via terminal 27.
Parameter 304 = Coasting stop, inverse [0].
- Terminal 42 Output
Parameter 319 = Torque limit and stop [27].
- Terminal 01 Relay output
Parameter 323 = Mechanical brake control [32].
MG.51.A1.02 - VLT is a registered Danfoss trade mark
103
Special functions
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