Danfoss Sensorless Pump Control Operating guide
■ Contents
Sensorless Pump Control for VLT®6000 HVAC / FCM 300
Functionality
How Does It Work? ................................................................................................ 3
Limitations .............................................................................................................. 5
Parameter Setting - Head ....................................................................................... 6
Par. 705 Quadratic Head ........................................................................................ 6
Par. 707 Head Qmin .............................................................................................. 6
Par. 716 Head Working Point ................................................................................. 6
Par. 717 Flow Working Point .................................................................................. 7
..................................................................................................... 2
Control Principle ............................................................................................. 8
Parameter Setting - Control .................................................................................... 10
Par. 701 Power Error .............................................................................................. 10
Par. 702 Delta Frequency ....................................................................................... 10
Par. 703 Integral Power .......................................................................................... 10
Par. 704 Integral Frequency .............. ..................................................................... 10
Programming other Functionalities ...................................................... 11
Par. 708 Power Compensation .............................................................................. 11
Analog Output ........................................................................................................ 12
Par. 720 AO Max Value .......................................................................................... 12
Analog Input ........................................................................................................... 13
Read-outs in LCP ................................................................................................... 14
Power/Frequency Read-out ................................................................................... 15
VLT 6000 ................................................................................................................ 16
Measuring Values ........................................................................................... 17
Introduction ............................................................................................................ 17
Installation and Setup of the Software .................................................................... 17
Installation .............................................................................................................. 17
Entering Pump Data ............................................................................................... 18
Number of Measurements ...................................................................................... 20
Other Functionalities of the Program ....................................................................... 20
Data and Read-outs ............................................................................................... 21
MG.10.T1.02 - VLT is a registered Danfoss trademark
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Sensorless Pump Control for VLT®6000 HVAC / FCM 300
■Functionality
Sensorless Pump Control (Sensorless) has been
developed to enable the drive to control the pressure
(Head) in a circuit with non-compressible liquid,
e.g. water, WITHOUT using a pressure transducer.
This has several advantages such as:
• Cost savings as there is no need for a
pressure transducer.
• Increased reliability, as there are no additional
components (transducer, cable, connections)
that can cause malfunction.
• No maintenance and exchange of pressure
transmitters.
• Very dynamic with a response time of
only 1-2 seconds.
• Increased energy savings.
Sensorless contains three different ways of
controlling the pressure where the choice depends
onthetypeofapplication.
Constant Head: The controller keeps a constant head
across the pump regardless of the flow through the
pump. Does not take pipe friction loss into account.
Proportional linear head: The controller increases the
head across the pump when the flow through the
pump increases, and it decreases the head when the
flow decreases. Takes pipe friction loss into account,
with a linear approximation to the real system curve.
Proportional, quadratic Head: Same as Proportional
Head, but with a quadratic Head curve instead of
linear. Takes pipe friction loss into account, with a
quadratic approximation to the real system curve.
In the manual, these three types of pressure control
are referred to as the user-defined head.
Marked area: Energy savings compared to
constant head control.
(P = K x Flow x Head)
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MG.10.T1.02 - VLT is a registered Danfoss trademark
Sensorless Pump Control for VLT®6000 HVAC / FCM 300
■How Does It Work?
Sensorless is based on the relations between frequency, flow, head and power. So consequently the drive
needs the data shown in the graphs below as input for the calculations. The data are pump specific and need
to be found by measurement. Alternatively, the data can be found by data sheet from the pump supplier if
accurate enough.
The graph below shows a n example of some measured values for flow/head on a typical centrifugal pump.
Head/flow (H/Q) Curves on a 1.5 kW pump
Functionality
The graph below shows the measured values for flow/power.
Power/flow (P/Q) Curves on a 1.5 kW pump
MG.10.T1.02 - VLT is a registered Danfoss trademark
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Sensorless Pump Control for VLT®6000 HVAC / FCM 300
With these values it is possible to create the relation between Power and frequency (P/f curve).
Power/frequency (P/f) Curves on a 1.5 kW pump
With these relations it is now possible to control the pressure (e.g. keeping it constant if that is desired) by
controlling the frequency according to the p ower measurement.
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MG.10.T1.02 - VLT is a registered Danfoss trademark
Sensorless Pump Control for VLT®6000 HVAC / FCM 300
■Limitations
A criteria for Sensorless to work is that there must be a
clear one-to-one relation between head and flow, and
power and flow, (i.e. only one H-value to one Q-value
and opposite) as this forms the basis for the P/f-curve.
Sensorless can be used with ce ntrifugal pumps
that have radial impeller. On pumps with mixed
flow impellers t here is only limited use as the power
curve is typically flat at high flow rates. A centrifugal
pump with axial impeller cannot be controlled with
sensorless control due to the particular shape of
the head curve. The graphics below show typical
characteristics for the different pump types.
Axial impeller
=200 min
n
q
-1
Not possible
Other limitations: Sensorless control is limited to
non-compressible liquids such as water. Furthermore
the solution is recommended only in closed systems.
Functionality
Radial impeller
=20 min
n
q
-1
Possible
Mixed flow impeller
=80 min
n
q
-1
Limited
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Sensorless Pump Control for VLT®6000 HVAC / FCM 300
This parameter activates the Sensorless control:
Par. No. Par. Name Selection Default Description
Par. 700 (SENSOR-
LESS CONTROL)
The following parameters must be set to make Sensorless work:
VLT 6000 FCM
Par. 100 must be OPEN LOOP Par. 003 must be LOCAL
Par. 101 must be MULTIPLE M OTORS Par. 100 mus t be O PEN LOOP
- Par. 101mustbeVTHIGH
FCM: OFF/ON
VLT 6000:
ENABLE/DISABLE
OFF/DISABLE Set parameter to enable/ON
to activate Sensorless control.
Please observe that this parameter
must be set to disable when doing
measurements.
The following parameters determine the user-defined
head for the system.
■Par. 705 Quadratic Head
Par. 705 Quadratic head
(QUADRATIC HEAD)
Value:
ON/OFF
Function:
Used when selecting the desired type of
Sensorless control: Quadra
tic head or linear
(proportional or constant) head.
Description of choice:
OFF: Generates a linear head/flow reference between
Head Q
(Par. 707) and Head working point (Par. 716).
min
ON: Generates a quadratic head/flow reference
between Head Q
(Par. 707) and Head
min
working point (Par. 716)
■Par. 707 Head Qmin
Par. 707 Head Q
min
(HEAD QMIN)
Value:
0-100%
✭ OFF
✭ 100%
Function:
Sets the head reference at zero flow as a percentage
of the value specified in Par. 716.
Description of choice:
Set a value between
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0 and 100%.
Sensorless Pump Control for VLT®6000 HVAC / FCM 300
■Par. 716 Head Working Point
Par. 716 Head Working Point
(HEAD WORK. POINT)
Value:
FCM
0-2000 kPa
VLT 6000
0-20000 kPa
Function:
Defines the head at the working point.
✭ 10 kPa
✭ 10 kPa
Description of choice:
Set the value in kPa according to the desired head
working point parameter 717. Note the difference
in range for FCM and VLT 6000.
■Par. 717 Flow Working Point
Par. 717 Flow Working Point
(FLOW WORK. POINT)
Value:
0-999 l/s
Function:
Defines the flow at the working point.
Description of choice:
Set the value in l/s according to the desired flow
working point parameter 716.
Functionality
✭ 1l/s
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