Regulation For Superheat: Self Adaptive Or Manual Operating Mode; Pressure Filtering - Sub Parameter; General Considerations; Manual - Emerson xm678d Operation And Installation Manual

Controllers for multiplexed cabinets wuth interior stepper driver
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Minimum number of steps: (0 to USt)
Allows selection of the minimum number of
steps. At this number of steps, the valve should
LSt
be closed. Read the manufacturer's data sheet to
set this parameter correctly.Configure the value
of this parameter within the allowed range of
functioning.
CAUTION! Changing this parameter will
require a valve restart.When the programming
mode ends, the controller will automatically
restart.
Maximum number of steps: (LSt to 800*10)
Allows the user to select the maximum number
of steps. At this number of steps, the valve
USt
should be opened completely. Read the
manufacturer's data sheet to set this parameter
correctly. Configure the value of this parameter
within the allowed range of functioning.
CAUTION! Changing this parameter will
require a valve restart.When the programming
mode ends, the controller will automatically
restart.
Extra step during closing phase: (0 to 255
(*10)) it sets the number of extra steps the
Est
controller performs, when the valve is closed at
start up, and during the pauses of regulation, to
force the closure of the valve.
Note: To set the ESt, the following steps has to be
done:
1. Set the kind of valve by the parameter tEP.
This pre-set the parameters related to the valve
2. Set the right value of ESt.
Step rate: (10 to 600 step/sec)
The maximum speed to change step without
Sr
losing precision (losing steps). It is
recommended to set this parameter below the
maximum speed.
Current per phase (only for bipolar valves): 
(0 to 100*10mA)
CPP
The maximum current per phase used to drive
the valve. (Used only with bipolar valves)
Holding current per phase (only for bipolar
valves): (0 to 100*10mA)
CHd
The current per phase when the valve is stopped
for more than 4 minutes. (Used only with
bipolar valves)

Pressure Filtering - Sub Parameter

16 Regulation for
16.1. Pressure Filtering - Sub
For optimal SH regulation, use a filtered value of
pressure. This can be accomplished by using the
parameter Sub.
Suggested values:
• From 1-5 evaporators for each racks: Sub = 20
• From 6-30 evaporators for each racks: Sub = 15
• More than 30 evaporators for each racks: Sub =10

16.2. General Considerations

The controller can regulate the superheat in manual or
self adaptive mode, according to the value of the
parameter AMS, auto-tuning enabling.
• With AMS = n: the normal SH regulation is
performed.
• With AMS = y: the self adaptive SH regulation is
performed.
16.3. Manual Operating
The temperature and SH regulation can be performed
in two ways, according to the value of the parameter
CrE: on/off or continuous. See the Standard
temperature regulation in details below.
Regulation for Superheat: Self Adaptive or Manual Operating Mode • 27
Superheat: Self
Adaptive or

Manual

Operating Mode
Parameter

Mode - AMS = NO

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