Emerson Vilter MicroVission - Page 233

C - 3
MicroVission Controller • Operation and Service Manual • Emerson • 35391MV 1.3
Appendix C • Remote Control and Monitoring
Typically, the following registers are setup (written to)
before a “Start” command is issued to the compressor.
Modbus Register 40172 - Remote Control Select
• 0 = Auto Control. This selection denes that the
MicroVission will control compressor capacity from
its internal Control Setpoints.
• 1=PulseLoad/Unload.Thisselectiondenesthat
the MicroVission will control compressor load from
contents of Remote Step Load register 40174 and
Remote Step Unload register 40175.
• 2=HoldCapacity%.Thisselectiondenesthatthe
MicroVission will control compressor capacity from
contents of Capacity Hold % register 40176.
If Hold Capacity % is selected, then it is typical to write a
Capacity Hold value to register 40176 before the com-
pressor is started, typically 0% to prevent the compres-
sor from loading immediately.
Modbus Register 40176 - Capacity Hold %
Value = 0-100
Cap Hold Operation without VFD
TheCapacityHold%valuedenesthecapacityforthe
compressor to operate at. The MicroVission will load the
steps based on the Capacity Hold % value provided in the
range of 0% - 100%.
Forexample,IfthenumberofUnloadersconguredin
conguration screenis4(25%,50%,75%,100%),then
Load Steps would be 0%, 25%, 50% & 75%. Progress bar
on Main Screen should display capacity at which the
compressor is currently operating. The rules of capacity
hold algorithm are:
1. If Capacity Hold % value is greater than or equal to
(NextLoadStep%-Offset),stepwillbeadded.When
Capacity Hold % value is above 20% (25 – 5), then
compressor will operate at 25% capacity and prog-
ress bar should be loaded at 25%, refer Figure C-4.
WhenCapacityHold%valueisabove45%(50–5),
then compressor would operate at 50% capacity and
progressbarshouldbeloadedat50%.WhenCapacity
Hold % value is above 70% (75 – 5), then compres-
sor would operate at 75% capacity and progress bar
should be loaded at 75%. When Capacity Hold %
value is above 95% (100 – 5), then compressor would
operate at 100% capacity and progress bar should be
loaded at 100%.
2. If Capacity Hold % value is less than or equal to
(Previous Load Step % + Offset), step will be removed.
WhenCapacityHold%valueisbelow80%(75+5),
then compressor will operate at 75% capacity and
progressbarshouldbeloadedat75%.WhenCapacity
Hold % value is below 55% (50 + 5), then compressor
will operate at 50% capacity and progress bar should
beloadedat50%.WhenCapacityHold%valueisbe-
low 30% (25 + 5), compressor would operate at 25%
capacity and progress bar should be loaded at 25%.
WhenCapacityHold%valueisbelow5%(0+5),then
compressor would operate at 0% capacity and prog-
ress bar should be loaded at 0%.
3. If Capacity Hold % value varies within the range of
(Previous Load Step % + Offset) and (Next Load Step
% - Offset), then compressor capacity would not vary
andwouldstayatcurrentstep.WhenCapacityHold
% value is greater than 30% (25 + 5) and lesser than
45% (50 - 5), then compressor will operate at 50% ca-
pacity and progress bar should be loaded at 50%.
Figure C-3. Setting MicroVission in Remote Mode