WhisperAir™ Oil-free Rotary Tooth Compressor
Model Series PCC & PCCMD – 50 HP
Powerex • 150 Production Drive • Harrison, OH 45030 • USA
(T) 1.888.769.7979 • (F) 513.367.3125 • www.powerexinc.com
IN594501AV • 02/2016
Page 2 of 32
Cooling System
The compressor is equipped with an intercooler (Ci),
aftercooler (Ca), and oil cooler (Co) to cool down the
compressed air and oil. Cooling fan (FN) generates the
cooling air.
Load Operation
When the pressure drops down to the load setting
pressure, the solenoid valve is opened, and air is
supplied to intake valve (IV) through pulsation damper
(PD). When the air reaches intake valve (IV), the valve
is opened and the compressor starts load operation.
Unload Operation
When the demand for compressed air is satisfied and
reaches the unload setting pressure, the solenoid valve
is closed, and air is released to atmosphere through
unload silencer (US). When intake valve (IV) is closed,
the compressor switches to unload operation.
VFD Model operation:
At low system pressures the VFD control increases
the main motor speed to 106% of nominal in order to
increase air output. Because of the lower pressure,
motor load is acceptable at this speed.
When the demand for compressed air is low and
system pressure rises near to the final pressure, the
VFD control slows down the motor to reduce air
output. If the air output can match the system demand
the control will seek to maintain pressure at a balance
point between supply and demand. Speed can be
reduced to 40% of nominal. If demand is lower than
this, the system pressure will continue to rise and the
unload control will take over. Speed is maintained at
40% while unloaded. When demand returns, the
control will increase speed and reload the compressor.
If the unit remains unloaded, an automatic shutdown
will occur after 7 minutes of total run time. The system
will automatically restart when pressure drops. The
VFD reduces wear on the intake valve parts, reduces
power consumption when demand is less than 100%
and reduces the undesirable electrical supply system
effects of starting and stopping the main motor.
Safety Guidelines
A SEPARATE SAFETY BOOKLET IS PROVIDED ALONG
WITH THIS MANUAL. READ AND UNDERSTAND THE
SAFETY BOOKLET.
This manual contains information
that is very important to know and understand. This
information is provided for SAFETY and to PREVENT
EQUIPMENT PROBLEMS. To help recognize this
information, observe the following symbols. MAKE
SURE EVERYONE OPERATING OR SERVICING THE
COMPRESSOR READS AND UNDERSTANDS ALL THE
INFORMATION PROVIDED.
The operator must install
equipment in a safe location and is responsible for
following all related local work safety requirements
and regulations.
Danger indicates an
imminently hazardous
situation which, if not avoided, WILL result in death or
injury.
Warning indicates a
potentially hazardous
situation which, if not avoided, COULD result in death
or serious injury.
Caution indicates a
potentially hazardous
situation which, if not avoided, MAY result in minor or
moderate injury.
Notice indicates important
information which, if not
followed, may cause damage to equipment.
Powerex shall not be responsible for any damage or
injury caused by inappropriate operation, or from not
following the instruction manual.
