Danfoss VLT 2800 Design Manual page 106

Programming
Depending on pump size or curve select [32] W or [8] kW
in parameter 009 Large display readout for fine tuning.
469 No Flow Power Compensation
Value:
0.01 - 2
Function:
This function is used for an off-set of the no/low flow
4 4
power curve, which can be used as a safety factor or for
fine tuning of the system.
Description of choice:
The factor is multiplied to the power values. E.g. 1.2
increases the power value with 1.2 over the whole
frequency range.
470 Dry Run Time Out
Value:
5-30 s
Function:
If the power is below the no/low flow power curve,
running at maximum speed for the time set in this
parameter, the adjustable frequency drive trips 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 tripping.
Manual or automatic restart can be programmed in
parameters 405 Reset function and 406 automatic restart
time.
The value 30 disables dry-run detection.
471 Dry Run Interlock Timer
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 adjustable
frequency drive.
Description of choice:
Parameter 406 Automatic restart time still determines how
frequent an attempt to reset a trip is performed. If, for
instance, parameter 406 Automatic restart time is set to 10 s
and parameter 405 Reset function is set to [10] Automatic
Reset x10, the adjustable frequency drive attempts to reset
the trip 10 times within 100 s. If parameter 471 Dry Run
Interlock Timer is set to 30 minutes, the adjustable
frequency drive consequently is unable to perform
automatic reset of dry run trip and needs a manual reset.
104
Design Guide
484
Value:
OFF/000.1s - 360.0 s
Function:
Allows the motor/equipment to be brought up to
1.2
minimum speed (frequency) at a rate different than the
normal ramp-up rate (parameter 207 Ramp-up time 1).
Description of choice:
As an example, vertical pumps and other equipment often
have a requirement not to operate below a minimum
speed any longer than necessary. Damage and excessive
wear can occur when operating below minimum speed
(frequency) for too long time. The initial ramp is used to
accelerate the motor/equipment quickly to minimum
speed at which point, the normal ramp-up rate (parameter
207 Ramp-up time 1) is made active. The range of
adjustment of the initial ramp is from 000.1 s to 360.0 s;
31 = OFF
adjustable in 0.1 second 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.
Illustration 4.20 Initial Ramp Example
30 min.
4.6.3 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 adjustable frequency drive, set for closed loop
operation, uses an adjustable fill rate, a filled-pressure
setpoint, an operating pressure setpoint, and a pressure
feedback.
Fill mode is available when:
Danfoss A/S © Rev. May/2014 All rights reserved.
Initial ramp
•
The frequency converter is in closed loop mode
(parameter 100 Configuration).
•
Parameter 485 Fill Rate is not 0
•
Parameter 437 Process PID normal/inverse control is
set to normal
OFF
MG27E402