Danfoss VLT AQUA Drive FC 202 Programming Manual page 52

Parameter Description
1-79 Pump Start Max Time to Trip
Range:
3 3
3.3.9 1-8* Stop Adjustments
1-80 Function at Stop
Option:
[0] Coast
[1] DC Hold/
Motor
Preheat
1-81 Min Speed for Function at Stop [RPM]
Range:
Size related
*
RPM]
1-82 Min Speed for Function at Stop [Hz]
Range:
Size related
*
Hz]
3.3.10 Advanced Minimum Speed
Monitoring for Submersible Pumps
Some pumps are very sensitive to operating at low speed.
Typical reasons for this are insufficient cooling or
lubrication at low speed.
Under overload conditions, the frequency converter
protects itself using its integral protection features, which
include lowering the speed. For example, the current limit
controller can lower the speed. This means that in some
cases the speed may go lower than the speed specified in
50
Function:
specified in this parameter, the frequency
converter trips. The time in this parameter
includes the time specified in 1-71 Start Delay. For
instance, this means that if the value in 1-71 Start
Delay is more or equal to value in
parameter 1-79 Pump Start Max Time to Trip, the
frequency converter never starts.
Function:
Select the frequency converter function after a
stop command or after the speed is ramped
down to the settings in parameter 1-81 Min Speed
for Function at Stop [RPM].
Available selections depend on
parameter 1-10 Motor Construction:
[0] Asynchron:
[0] coast
[1] DC-hold
[1] PM non-salient:
[0] coast
Leaves motor in free mode.
Energises motor with a DC holding current (see
parameter 2-00 DC Hold/Preheat Current).
Function:
[0 - 600 Set the speed at which to activate
parameter 1-80 Function at Stop.
Function:
[ 0 - 20.0 Set the output frequency at which to
activate parameter 1-80 Function at
Stop.
Danfoss A/S © Rev. 2014-01-21 All rights reserved.
Programming Guide
4-11 Motor Speed Low Limit [RPM] and 4-12 Motor Speed
Low Limit [Hz].
The advanced minimum speed monitoring feature trips the
frequency converter if the speed drops below a certain
value:
If the motor of the pump does not reach the speed
specified in 1-86 Trip Speed Low [RPM] within the time
specified in parameter 1-79 Pump Start Max Time to Trip
(ramping up takes too long), the frequency converter trips.
Timers for 1-71 Start Delay and parameter 1-79 Pump Start
Max Time to Trip start at the same time when the start
command is issued. For instance, this means that if the
value in 1-71 Start Delay is more or equal to value in
parameter 1-79 Pump Start Max Time to Trip, the frequency
converter will never start.
N
RPM
N
1-86
0
T
1-71
T
1-79
N
1-86
1
Illustration 3.11 Advanced Minimum Speed Monitoring
1-86 Trip Speed Low [RPM]
Range:
Size
related
*
1
T
T
1-79
1-71
1-71 Start Delay.
Parameter 1-79 Pump Start Max Time to Trip. This time
includes the time in T .
1-71
1-86 Trip Speed Low [RPM]. If the speed drops below
this value during normal operation, the frequency
converter trips.
Normal operation.
Function:
NOTICE
[ 0 -
par.
This parameter is only available if
4-13
parameter 0-02 Motor Speed Unit is set
RPM]
to [RPM].
Enter the low limit for the motor speed at
which the frequency converter trips. If the
value is 0, the function is not active. If the
speed at any time after the start (or during
a stop) falls below the value in the
parameter, the frequency converter trips
with the alarm Speed Limit.
T
MG20O702