Daikin DPS012 - VFD Compressor Operation - DPS 016-028

VFD Compressor Operation – DPS 016–028
VFD compressor modulation is controlled by a Mobus
®
signal
from the unit controller. The minimum VFD compressor speed
is 25 rps (1500 rpm) and the maximum VFD compressor speed
is 100 rps (6000 rpm), but the minimum and maximum limits
per unit may vary depending on operating conditions and unit
model size.
The VFD compressor is a 4 pole motor design that operates off
a frequency signal from the VFD between 50Hz and 200Hz.
At Start-up the VFD compressor will automatically ramp up to
50 rps for rst 10 seconds for lubrication requirements.
Crankcase heating for VFD Compressor is performed by the
VFD via DC-holding current through the motor windings.
VFD compressor modulation is additionally monitored and
adjusted in order to maintain operation within the approved
compressor operating envelope.
Table 10: VFD Compressor Modulation Ranges
DPS Unit
Model
VFD Modulation Range
VFD Min rps/
VFD Min V
VFD Max rps
VFD and Fixed
Comp(s) ON
VFD Comp Only
VFDMax rps/
VFDMaxV
1 Fixed ON
VFD1Max rps/
VFD1MaxV
016 25 rps/0 Vdc 60 rps/4.0 V 90 rps/6.0 V
018 25 rps/0 Vdc 100 rps/8.7 V 100 rps/10.0 V
020 25 rps/0 Vdc 100 rps/8.7 V 100 rps/10.0 V
025 25 rps/0 Vdc 85 rps/8.0 V 100 rps/10.0 V
028 25 rps/0 Vdc 85 rps/8.0 V 100 rps/10.0 V
* High and Low Oil Boost are explained on page 30
DPS Size 025 & 028, Two Compressor Units
If the VFD compressor were to become inoperative, the
unit can continue to operate on the remaining xed speed
compressor until the unit can be serviced.
When the VFD compressor is at its maximum speed and
more capacity is required, a xed speed compressor is started
while the VFD compressor is reduced to minimum speed at
which point it resumes modulating to maintain the discharge
temperature. When the VFD compressor is at its minimum
speed and less capacity is required, a xed speed compressor
is turned OFF while the VFD compressor is increased to
maximum speed at which point it resumes modulating to
maintain discharge temperature.
refrIgeraTIon sysTeM
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