Operating instructions
Dedicated compressor features
Alternatively use the built-in cascade
controller to operate the lead
compressor with variable speed,
while using the VLT® HVAC Drive to
manage on/off control of up to two
additional compressors.
Set point in temperature
The VLT® HVAC Drive calculates the
actual refrigerant temperature from
the measured pressure and refi nes
compressor operation accordingly
using the built-in PID controller.
The temperature setpoint for this
calculation is set in degrees via the
Local Control Panel or MCT 10 – and
not as a pressure value.
Fewer starts and stops
A maximum number of start/stop
cycles within a given period of time
can be set via the LCP or MCT10.
Since start-up is the most critical part
of compressor operation this extends
compressor lifetime.
Quick start-up
The VLT® HVAC Drive off ers a feature
to open a bypass valve and let the
compresser start quickly without
load.
The VLT® HVAC Drive provides
increased break away torque and can
give 110% torque for 60 seconds in
normal operation.
Improving energy
effi ciency ... continuously
Traditional commercial air condi-
tioning systems are designed for
effi cient operation at peak load
conditions, so systems are actually
oversized about 85% of the time or
more. Consequently at part load
conditions, the systems has excess
capacity, with signifi cant and costly
energy waste. Variable speed will
contribute to a higher COP and lower
energy consumption with load
matched to actual demand while
delivering a solid return on invest-
ment (ROI).
Premium torque control
The VLT® HVAC Drive has been
designed to off er fl exible, intelligent
control of compressors, making it
even easier to optimize cooling
capacity with constant temperature
and pressure levels for water chillers,
and other typical compressor applica-
tions in HVAC.
Replace a cascade with
a single compressor
The VLT® HVAC Drive provides the
same level of fl exibility with one
large compressor instead of a cascade
of 2 or 3 smaller compressors. The
VLT® HVAC Drive operates all
compressors at a far more refi ned
range of speeds than normal – even
above nominal speed – meaning that
one large compressor is suffi cient.
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