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 fl ow – a condition that can cause
pump damage if not detected and corrected.
No fl ow based on motor
power and frequency
No-Flow Detection is based on the
measurement of power at specifi c
motor speeds. The drive monitors
actual power and motor frequency
and compares it to the calculated
no-fl ow power at specifi c speeds.
If the power measured at a specifi c
frequency is greater than the no-fl ow
power calculated by the drive, the
pump is producing fl ow. If the power
measured is less than the no-fl ow
power calculated by the drive, a
warning or alarm is generated to
notify the operator of the condition.
To determine the no-fl ow power level
throughout the speed range, the
drive generates a power vs. frequency
curve that represents the no-fl ow
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 diff erent 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
Benefi ts
Eliminates an external diff erential
pressure switch or fl ow 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
