QUANTUM™ HD COMPRESSOR CONTROL PANEL
OPERATION
090.040-O (MAR 12)
Page 80
DESCRIPTION: Use this screen to set the specifi c Drive
safeties information for a VSD (Variable Speed Drive) mo-
tor starter. These safeties are important for the safe op-
eration of the compressor and motor.
BASICS OF VFD OPERATION
Relying on user input as well as system pressures and
temperatures, the Quantum™ HD directs the Vari-
able Speed Drive to start or stop the compressor and
change the compressor’s speed to regulate capacity.
The setpoints that primarily control the operation of
the VSD are found on the Quantum HD’s Capacity
Control Setpoints and Motor Setpoints pages.
To start the compressor, the Quantum™ HD sends
a signal to the VSD to turn on the motor. When the
VSD receives the start command, it turns on the
motor and ramps up to the speed set by the VSD
Minimum Drive Output setpoint. At the same time if
the slide valve is below the Variable Speed Minimum
Slide Valve Position, it immediately loads to the Vari-
able Speed Minimum Capacity Valve Position.
As more capacity is required, the Quantum™ HD
loads Capacity Slide. The Capacity Control Settings
(on the Motor Setpoints page) can be confi gured to
cause the motor speed to increase at the same time,
but in most VSD applications the Capacity Control
Drive Speed setpoint is set to match the Minimum
Drive Output setpoint. In this confi guration the mo-
tor speed will remain at its minimum speed until the
slide valve loads above the Capacity Control Slide
Valve setpoint. If the slide valve cannot load due to
a slide valve load inhibit condition or because the
compressor cannot build differential pressure, the
motor speed will increase to meet the capacity re-
quirement.
When the Capacity Slide reaches the Capacity Slide
to Speed Transition setpoint, the motor speed can
then increase. At this point the Capacity Slide and
motor speed can continue to increase independently
of one another until the capacity requirement is met
or they reach their maximum values. If the compres-
sor is in Auto mode, the motor speed is controlled
by the VSD Proportional Band and VSD Integration
Time setpoints.
If less capacity is required, the Quantum™ HD will
fi rst decrease the motor speed. The motor speed
can drop as low as the Speed to Capacity Transition
setpoint. When the motor speed reaches this point,
depending on the Quantum™ HD’s confi guration, the
Capacity Valve may unload or the Quantum™ HD may
stop the compressor. If the Capacity Valve is permit-
ted to unload, it will not unload below the Variable
Speed Minimum Capacity Slide Position while the
compressor is running.
CONFIGURATION
Drive - VSD
ACCESSING:
Drive VSD
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