VLT
®
5000 Series
■ Special functions
400
400 Brake function/overvoltage control
(BRAKE FUNCTION)
Value:
✭Off (OFF)
[0]
Resistor brake (RESISTOR)
[1]
Overvoltage control (OVERVOL TAGE CONTROL)
[2]
Overvoltage control and stop
(OVERVOL T CTRL. & STOP)
[3]
Function:
The factory setting is Off [0] for VLT 5001-5062
380-500 V and 5001-5027 200-240 V. For VLT 5060-
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 VLT
frequency converter for connection of a brake resis-
tor.
The connection of a brake resistor allows a higher
intermediate circuit voltage during braking (generat-
ing 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 se-
lected 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 so as to use the
energy from the intermediate circuit. This is a very
useful function, e.g. if the ramp-down time is too
short, since tripping of the VLT 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 con-
trol function is required in all cases - also if stop is
pressed. The VLT frequency converter will n
ot stop
in the case of a stop command when the overvolt-
age control is active.
Select Overvoltage control and stop [3] if the over-
voltage control function is not required during
ramp-down after stop has been pressed.
Warning: If Overvoltage control [2] is used
at the same time as the supply voltage to
the VLT frequency converter is close to or
above the maximum limit, there is a risk that the mo-
t
or frequency will increase and that, consequently
,
the VLT frequency converter will not stop the motor
when stop is pressed. If the supply voltage is higher
t
han 264 V for 200-240 V units or higher than 550 V
for 380-500 V units, Overvoltage control and stop [3]
s
hould be selected so that the motor can be stopped.
401
401 Brake resistor, ohm
(BRAKE RES. (OHM))
Value:
Depends on the unit
✭ Depends on the unit
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
402 Brake power limit, kW
(BR.POWER. LIM.KW)
Value:
Depends on the unit
✭ Depends on the unit
Function:
This parameter gives the monitoring limit of the
power transmitted to the brake 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 =
397
2
xt
R x 120
For 380 - 500 V units: P =
822
2
xt
R x 120
403
403 Power monitoring
(POWER MONITORING)
Value:
Off (OFF)
[0]
✭Warning (WARNING)
[1]
Trip (TRIP)
[2]
✭
= factory setting. () = display text [] = value for use in communication via serial communication port
MG.51.A1.02 - VLT is a registered Danfoss trade mark
143
Programming
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