56
VLT
®
3500 HVAC
MG.35.B1.02 – VLT is a registered Danfoss trademark
Function:
Select one of the 3 ramp-down functions to extend
the overrun time in case of mains failure. The effect
will depend on the load and the mains voltage before
the failure.
Description of choice:
Uncontrolled stop
[0]:
The motor continues to run at the selected speed un-
til the controls cut out.
Ramp down 1
[1]:
The motor begins to ramp down immediately (para-
meter 216) until the controls cut out.
Ramp down 2
[2]:
The motor begins to ramp down immediately (para-
meter 218). If the ramp-down time is short, a regene-
rative effect may keep up the DC voltage, which
means that it takes longer before the controls cut out.
305 Cutting in on rotating motor
(FLYING START)
Value:
★
Disable (NO FLY START)
[0]
OK - same direction (SAME DIRECT)
[1]
OK - both directions (BOTH DIRECT)
[2]
Stop before start (CD-BRAKE @STAR)
[3]
Function:
This parameter is used when VLT 3500 HVAC cuts in
on a rotating motor (e.g. after a power failure).
★
= factory setting. Text in ( ) = display text. Figures in [ ] are used when communicating with the bus.
3.7 Parameter gr
oup 3
301 Start frequency (START FREQ)
Value:
0.0 - 10 Hz
★
0.0 Hz
Function:
It is possible to define an output frequency at which
the motor is to start.
Description of choice:
Programme the start frequency at which the motor is
to start.
302 Delayed start (START DELAY)
Value:
0.0 - 1 sec.
★
0.0 sec.
Function:
VLT 3500 HVAC starts at the start frequency (parame-
ter 301) and begins to ramp up when the start delay
has ended.
Description of choice:
Programme the desired time delay before VLT 3500
HVAC starts to ramp up.
303 High starting torque (HI START TORQ.)
Value:
0.0 - 1 sec.
★
0.0 sec.
Function:
A high starting torque means that a current approx. 2
x the current limit of parameter 209 is permitted.
However, the current is limited by the protection limit
of the inverter.
Description of choice:
Insert the time required to give as high a starting tor-
que as desired.
304 Mains failure (POWER FAIL)
Value:
★
Uncontrolled stop (NORM PWR DWN)
[0]
Ramp down 1 (RAMP DOWN)
[1]
Ramp down 2 (ALT. RAMP DOWN)
[2]
Start/stop functions and timers, group 3..
This parameter group includes special start/stop
functions, e.g. how to catch a spinning motor. It is
also possible to programme a timer for the relay
outputs.
■
Description of choice:
OK - same direction
[1]:
Chosen if the motor is only able to rotate in the same
direction when cutting in.
OK - both directions
[2]:
Chosen if the motor is able to rotate in both directions
when cutting in.
Stop before start
[3]:
Chosen if the motor is to be stopped by means of
DC-braking, before the motor is ramped up to the
desired speed. The DC braking time is to be set in
parameter 306.
The selected function is activated in accordance with
the diagram on next page.
