Danfoss VLT User manual

The perfect solution for
•Intelligent control
•HVAC system protection
•Remote status reporting
The VLT® HVAC Drive provides a new No-Flow detection feature
for pump systems. This feature is useful for detecting conditions
where a pump is producing no flow – a condition that can cause
pump damage if not detected and corrected.
No flow based on motor
power and frequency
No-Flow Detection is based on the
measurement of power at specific
motor speeds. The drive monitors
actual power and motor frequency
and compares it to the calculated
no-flow power at specific speeds.
If the power measured at a specific
frequency is greater than the no-flow
power calculated by the drive, the
pump is producing flow. If the power
measured is less than the no-flow
power calculated by the drive, a
warning or alarm is generated to
notify the operator of the condition.
To determine the no-flow power level
throughout the speed range, the
drive generates a power vs. frequency
curve that represents the no-flow
condition. This curve is generated by
the drive from two data points. These
power/frequency points can be
entered into the drive automatically
or manually.
Manual or Auto Set Up are available
The Auto Set Up automatically steps
the user through the commissioning
process, storing the data measured.
When the automatic set-up is selected
the output frequencies used are 50%
and 85% of maximum. Manual set-up
can be used when a different pair of
frequencies is desired.
Programming is quick and easy
The drive software makes program-
ming the No-Flow feature quick and
easy by choosing Pump Functions
and then No-Flow Function under the
Quick Menu.
Features Benefits
Eliminates an external differential
pressure switch or flow meter Reduce installation and maintenance cost
Eliminates wiring for external sensors Reduce installation and maintenance cost
A warning or alarm can alert operator
of the problem Provides proper operation of equipment and increases occupant comfort
Programming is quick and easy with
pre-programmed software Saves time and increases reliablity
VLT® No Flow Feature

Danfoss Drives, Ulsnaes 1, DK-6300 Graasten, Denmark, Tel. [phone], Fax [phone], www.danfoss.com/drives • E-mail: [e-mail]
MF004A02 VLT® is a trademark of Danfoss A/S Produced by KKM 2007.10
Programming for No-Flow detection
is simplified with a number of para-
meters that are pre-programmed into
the drive. Prior to programming this
feature, commission the drive by
using the parameters in the Quick
Menu Q2 Quick Set-Up. Then perform
the following steps for programming
No-Flow detection:
Par.# Description
Settings
Comments
Factory
setting Recommended setting
22-20 Low Power Auto Set-up Disable Enable Close the outlet valve for the pump before starting Auto Set-up. Select Enable
and follow the instruction on the LCP. After Auto Set-up is complete, open the
pump outlet valve.
The following parameters are accessed through the Main Menu and will be stored after pressing the [OK] key to save the results after the auto-tuning
22-33 Low Speed
[Hz] When Low Power Auto Set-up is used, 50% of the drive’s maximum frequency will be stored here. This can be manually edited, if desired.
22-34 Low Speed Power [kW] When Low Power Auto Set-up is used, the output power measured under
no-flow conditions at 50% speed will be stored here. This can be manually
edited, if desired.
22-37 High Speed
[Hz] When Low Power Auto Set-up is used, 85% of the drive’s maximum frequency will be stored here. This can be manually edited, if desired.
22-3 High Speed Power [kW] When Low Power Auto Set-up is used, the output power measured under
no-flow conditions at 85% speed will be stored here. This can be manually
edited, if desired.
These parameters are used after Auto Set-up and the No-Flow feature is operating
22 - 30 No-Flow Power When the drive is running, this parameter will show the power level that will
be interpreted as producing no flow at the current motor speed.
22 - 31 Power Correction
Factor 100% 110% This parameter is used to raise or lower the no-flow power curve to the percentage entered here. Values above 100% help ensure the drive reliably
detects no-flow.
The following parameters determine the action that the drive will take if a no flow condition is detected
22-21 Low Power
Detection Disable Enable To activate no-flow based on power
22-23 No-Flow Function Off Sleep Mode/
Warning/Alarm Select action
22-24 No-Flow Delay 10 sec. Set the time delay before the drive will perform the No-Flow Function.
Generally set longer than the decel ramp time.
The following parameters give and indication to a BMS if a no flow condition is detected
5-40 Function Relay [190] No-Flow Program one of the relays to selection [190], No-Flow. The selected relay will
be activated when No-Flow occurs.
Digital Output [190] No-Flow A digital output can be used to indicate a no flow condition. Use the
parameter that sets the function of the desired digital output.
The following are used if No-Flow is reported via serial communications
Protocol Warning Word
BACnet BV:77 No Flow
LonWorks nvoWarningword Bit 37
Modbus RTU TU Register 16930 Bit 6 = 1
Programming No-Flow detection