Danfoss VLT 2800 Manual page 109

470 Dry Run Time Out
(DRY RUN TIME OUT)
Value:
5-30 sec.
Function:
If the power is below the no/low flow power curve, run-
ning at max speed for the time set in this parameter,
the frequency converter will trip on Alarm 75: Dry run.
In open loop operation the maximum speed does not
necessarily need to be reached before tripping.
Description of choice:
Set the value to obtain the desired delay before trip-
ping. Manual or automatic restart can be programmed
in parameter 405 Reset function and 406 automatic re-
start time.
The value 30 disables Dry run detection.
471 Dry Run Interlock Timer
(Dry run int time)
Value:
0.5-60 min.
Function:
This timer determines when a trip due to dry run can
be automatically reset. When the timer expires, the
automatic reset of the trip can automatically restart the
frequency converter again.
Description of choice:
Parameter 406 Automatic restart time still determines
how frequent an attempt to reset a trip will be per-
formed. If for instance parameter 406 Automatic restart
time is set to 10 sec. and parameter 405 Reset func-
tion is set to Automatic Reset x10 the frequency con-
verter will attempt to reset the trip 10 times within 100
seconds. If parameter 471 is set to 30 min. the fre-
quency converter will consequently not be able to
perform automatic reset of dry run trip and will need a
manual reset.
484 Initial ramp
(INITIAL RAMP)
Value:
OFF/000.1s - 360.0 s
= factory setting, () = display text, [] = value for use in communication via serial communication port
MG.27.E2.02 - VLT is a registered Danfoss trademark
Function:
Allows the motor/equipment to be brought up to mini-
mum speed (frequency) at a rate different than the
normal Ramp-Up rate (param. 207).
31 = OFF
Description of choice:
As an example, vertical pumps and other equipment
often have a requirement to not operate below a min-
imum speed any longer than necessary. Damage and
excessive wear can occur when operating below min-
imum speed (frequency) for too long a period of time.
The Initial Ramp is used to quickly accelerate the mo-
tor/equipment to minimum speed at which point, the
normal Ramp-Up rate (parameter 207) is made active.
The range of adjustment of the Initial Ramp is from
000.1 second to 360.0 seconds; adjustable in 0.1 sec-
ond increments. If this parameter is set to 000.0, OFF
is displayed in this parameter, the Initial Ramp is not
active, and the normal Ramp-Up is active.
30 min.
Fill Mode
Fill Mode eliminates the occurrence of water hammer
associated with the rapid exhausting of air from piping
systems (such as Irrigation systems).
The frequency converter, set for Closed Loop opera-
tion uses an adjustable Fill Rate, a "Filled Pressure"
setpoint, an operating pressure setpoint, and a pres-
sure feedback.
Fill Mode is available when:
• The VLT 2800 drive is in Closed Loop mode
(parameter 100).
•
Parameter 485 is not 0
• Parameter 437 is set to NORMAL
After a start command, Fill Mode operation begins
when the frequency converter reaches minimum fre-
quency - set in parameter 201.
The "Filled" Setpoint - parameter 486- is actually a
OFF
setpoint limit. When minimum speed is reached, the
pressure feedback is looked at, and the frequency
converter begins to ramp to the "Filled" pressure set-
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