Brake Function/Overvoltage Control; Brake Resistor, Ohm; Brake Power Limit, Kw; Power Monitoring - Danfoss VLT 5000 FLUX Operating Instructions Manual

400 Brake function/overvoltage control

(BRAKE FUNCTION)
Value:
Off (OFF)
Resistor brake (RESISTOR)
Overvoltage control (OVERVOLTAGE CONTROL)
Overvoltage control and stop
(OVERVOLT CTRL. & STOP)
Function:
The factory setting is Off [0] for VLT 5001-5062
380-500 V and 5001-5027 200-240 V. For VLT
5075-5250 380-500 V and 5032-5052 200-240 V
the factory setting is Overvoltage control [2].
Resistor brake [1] is used for programming the
frequency converter for connection of a brake resistor.
The connection of a brake resistor allows a
higher intermediate circuit voltage during braking
(generating operation).
The Resistor brake [1] function is only active in units
with an integral dynamic brake (SB and EB units).
Overvoltage control (excl. brake resistor) can be
selected as an alternative. This function is active
for all units (ST, SB and EB).
The function ensures that a trip can be avoided if the
intermediate circuit voltage increases. This is done
by increasing the output frequency to limit the voltage
from the intermediate circuit. This is a very useful
function, e.g. if the ramp-down time is too short, since
tripping of the frequency converter is avoided. In this
situation, the ramp-down time is extended.
NB!:
Please note that the ramp-down time is extended
in the case of overvoltage control, which in
some applications may not be appropriate.
Description of choice:
Select Resistor brake [1] if a brake resistor
is part of the system.
Select Overvoltage control [2] if the overvoltage control
function is required in all cases - also if stop is pressed.
The frequency converter will stop in the case of a stop
command when the overvoltage control is active, but
not necessarily follow the deceleration ramp.
Select Overvoltage control and stop [3] if the
overvoltage control function is not required during
ramp-down after stop has been pressed.
= factory setting. () = display text [] = value for use in communication via serial communication port
MG.55.A6.02 - VLT is a registered Danfoss trademark
VLT
Warning: If Overvoltage control [2] is used
at the same time as the supply voltage
to the frequency converter is close to or
[0]
above the maximum limit, there is a risk that the motor
[1]
frequency will increase and that, consequently, the
[2]
frequency converter will not stop the motor when stop
is pressed. If the supply voltage is higher than 264 V
[3]
for 200-240 V units or higher than 550 V for 380-500
V units, Overvoltage control and stop[3] should be
selected so that the motor can be stopped.

401 Brake resistor, ohm

(BRAKE RES. (OHM))
Value:
ohm
Function:
This parameter gives the ohmic value of the brake
resistor. This value is used for monitoring the
power to the brake resistor provided this function
has been selected in parameter 403.
Description of choice:
Set the present resistor value.

402 Brake power limit, kW

(BR.POWER. LIM.KW)
Value:
kW
Function:
This parameter gives the monitoring limit of the
brake power transmitted to the resistor.
Description of choice:
The monitoring limit is determined as a product of
the maximum duty cycle (120 sec.) that will occur
and the maximum power of the brake resistor at that
duty cycle according to the following formula.
For 200 - 240 V units: P =
For 380 - 500 V units: P =

403 Power monitoring

(POWER MONITORING)
Value:
Off (OFF)
Warning (WARNING)
Trip (TRIP)
®
5000 FLUX
Depends on the unit
Depends on the unit
[0]
[1]
[2]
103