Special Functions - Danfoss VLT 5000 Series Instruction Manual

Special functions

400 Brake function/overvoltage control
(BRAKE FUNCTION)
Value:
Off (OFF)
Resistor brake (RESISTOR)
Overvoltage control (OVERVOLTAGE CON-
TROL)
Overvoltage control and stop
(OVERVOLT CTRL. & STOP)
Function:
The factory setting is Off [0] for VLT 5001-5027
200-240 V, VLT 5001-5102 380-500 V and VLT
5001-5062 525-600 V. For VLT 5032-5052 200-240 V,
5122-5552 380-500 V and VLT 5042-5602 525-690 V
the factory setting is Overvoltage control [2].
Resistor brake [1] is used for programming the adjust-
able frequency drive for connection of a brake resistor.
The connection of a brake resistor allows a higher in-
termediate 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 selec-
ted 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 func-
tion, e.g. if the ramp-down time is too short, since
tripping of the adjustable frequency drive is avoided.
In this situation, the ramp-down time is extended.
NOTE
Please note that the ramp-down time is
extended in the case of overvoltage con-
trol, 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.
= factory setting, () = display text, [] = value for use in communication via serial communication port
MG.51.C5.22 - VLT is a registered Danfoss trademark.
®
VLT 5000 Series
The adjustable frequency drive will not stop in the case
of a stop command when the overvoltage control is
active.
Select Overvoltage control and stop [3] if the overvolt-
age control function is not required during ramp-down
after stop has been pressed.
[0]
[1]
Warning: If Overvoltage control [2] is used
at the same time as the supply voltage to
the adjustable frequency drive is close to
[2]
or above the maximum limit, there is a risk
that the motor frequency will increase and
[3]
that, consequently, the adjustable fre-
quency drive will not stop the motor when
stop is pressed. If the supply voltage is
higher than:
• 264 V for 200-240 V units
• 550 V for 380-500 V units
• 660 V for 525-600 V units
• 759 V for 525-690 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:
Depends on the unit
Function:
This parameter gives the ohmic value of the brake re-
sistor. This value is used for monitoring the power to
the brake resistor provided this function has been se-
lected in parameter 403.
Description of choice:
Set the present resistor value.
402 Braking energy limit, kW
(BR.POWER. LIM.KW)
Value:
Depends on the unit
Depends on the unit
Depends on the unit
125