Danfoss VLT 5000 Series Operating Instructions

VLT
®
5000 Series
Special
functions
3. The frequency converter trips and Flying
start is active.
4. The frequency converter momentarily
releases the motor. Flying start is activated
and catches the motor again.
■ Normal/high overload torque control,open loop
This function enables the frequency converter to perform
a constant 100% torque, using an oversize motor.
The choice between a normal or a high overload torque
characteristic is made in parameter 101.
Thisisalsowheretochoosebetweenahigh/normal
constant torque characteristic (CT) or a high/normal
VT torque characteristic
If a high torque characteristic is chosen, a rated
motor with the frequency converter obtains up to
160% torque for 1 min. in both CT and VT. If a
normal 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
characteristic for an oversize motor is that the 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
regulator which is activated when the motor current,
and thus the torque, is higher than the torque
limits set in parameter 221 and 222.
When VLT 5000 Series is at the current limit
during motor operation or regenerative operation,
the 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 frequency
converter can only be stopped by means of terminal
27 if set to Coasting stop, inverse [0] or Reset and
coasting stop, inverse [1]. A signal on terminals
16-33 will not be active until the frequency 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 frequency converter via a ‘standard’
stop command, while at the same time activating
the external electro-mechanical brake.
The example given below illustrates the programming
of 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
terminal 42 to Torque limit and stop [27].
MG.51.A9.02 - VLT is a registered Danfoss trademark
95

Danfoss VLT 5000 Series Specifications

General

Brand	Danfoss
Model	VLT 5000 Series
Category	DC Drives
Language	English