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Technical Manual MSR Universal Stage Controller
Motor Control
The MSR-unit can control up to 4 single motors or multi-stage
machines with up to four stages.
The kind of machines and the number of stages will be fixed with
parameters P16 thru P19.
Example:
!! If stage No.4 is not selected, relay K4 works as an alarm
relay automatically !!
Automatic Base Load Change (Stage Sequence Change)
The built-in base load change function (P25 ON/OFF) regards
the relative runtimes of the single stages and cares for
approximately the same motor runtimes after a longer time.
If multistage machine types are used, only the runtime of the
leading stage (= motor on) will be considered.
Load Limitation
Via one of the both control inputs OK1/OK2 a load limitation
function can be initiated, e.g. for saving energy. P24 fixes how
many stages remain for control purposes after this function has
been started, the stages will be disabled within a few seconds.
Minimum Idle Time
If a load is switched off by a relay, this relay can be switched on again
not before the time set with P22 is over. P22 affects all relay stages.
Relay Switching Mode
With P23 the switching mode of relay K1 and K4 can be changed
for special purposes:
P23 = 0
K1 and K4 active ON
Standard setting
P23 = 1
K1 active OFF (relay de-activated), K4 active ON
With this setting e.g. an emergency operation
can be realized, compressor 1 will be controlled by
the N/C so it would run continuously if the MSR
fails.
P23 = 2
K1 active ON, K4 active OFF
Advisable if only 3 compressors/stages should
be controlled and you want to use relay K4 as
an active OFF alarm relay.
P23 = 3
K1 active OFF, K4 active OFF
Can be used for emergency operation & alarm
relay controlling 3 compressors or if compressor 1
and 4 should run in emergency mode.
Programming
Relay outputs
Machine
P16 P17 P18 P19
K1 K2 K3 K4
4 single machines
1
1
1
1
1
1
1
1
1 multistage (4 stages)
4
0
0
0
1.1 1.2 1.3 1.4
2 dual stage machines
2
2
0
0
1.1 1.2 2.1 2.2
1 dual stage and two
single machines
2
1
1
0
1.1 1.2 2
3
Trend Analysis (STAN)
The stage controllers of the series MSR contain an autoadaptive
algorithm to recognize actual value tendencies (STAN = Switch
Tendency Analysis).
This algorithm effects an essential reduction of on/off cycles of the
machines and a noticeable increased control accuracy.
STAN works foreseeing, recognizes the trend of the actual value
and decides, based on the captured data, about the necessity of
switching on/off a machine.
A typical example of a conventional control is the following state:
Machines run, the actual value approaches itself to the setpoint,
the foreward delay of the next stage is still running. If the next stage
will switch on now, the tendency will be increased, probably the
setpoint range will be left quickly to low values. The high deviation
to low values then effects mostly that multiple or all machines
switch off and a quick rise of the pressure with essential overshoot
of the setpoint range. The plant 'oszillates'.
This behaviour must be suppressed by increasing the switch delay
times, but this makes the control slow and enables wider setpoint
deviations.
STAN avoids the effects in this example: STAN recognizes that
the actual value moves to the setpoint direction and disables that
machines or stages will switch on. If the tendency continues, the
setpoint will be reached without additional power. Oszillating or
essential decreasing of the setpoint range will be avoided safely.
STAN works complety autoadaptive, no parameters must be set.
Because of the fuzzy logic of the algorithm, disadvantageous
effects like moving setpoint deviations will be recognized, so they
cannot affect the tendency analysis.
If the MSR works as a brine/chiller controller, STAN
keeps disabled.
The single Advantages:
• Essential reduction of on/off cycles and so an increased
lifetime of components, especially of compressors.
• More accurate, more regular control with less setpoint
deviations than a "normal" stage controller. This affects
lower energy consumption and the cold production works
with a constant, high efficiency ratio.
• The existing expansion valves work more regular and so
more efficient, based upon the lower suction pressure
variations resp, condenser pressure variations.
• The average T falls. This affects a lower icing of the
evaporators, and the product quality rises because of the
lower de-humidifying (counters of meat/cheese, meat
storages).
• The reaction times of the plant meet the demands, because
the delay times must not be increased additionally to
damp the switching behaviour.
Essential Advantages Overview:
• Trend recognition, the direction of the actual value's move
will be recognized and the switch characteristic of the
machines will be changed.
• Intelligent detection of 'oszillating', permanent setpoint
deviations, which have no effect on the trend recognition.
• Autoadaptive, while run-up or service STAN requires no
parameters to be set.
