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51
ON
OFF r01 r01+r07+r02/4 r01+r07+r02*3/4
r01+r07 r01+r07+r02/2 r01+r07+r02/2 r01+r07+r02 r01+r07+r02
ON
OFF
r03-r07-r02/4 r03-r07-r04
r03-r07+r04/4
r03 r03-r07
r03-r07+r04*3/4 r03-r07+r04*3/4
r03 r03+r12
r10
r11
ENGLISH
μC 2 SE - +030220426 - rel. 2.1 - 09.06.2010
less capacity is required, the second step will be deactivated fi rst, and then the compressor. There is
no rotation between the compressor and the valve. If extra capacity is required, the second circuit
will start with compressor 2 and then, if required, the valve is operated.
When stopping, the valve is managed fi rst and then the actual compressor as a whole. Both
FIFO logic and timed operation will involve either one circuit or the other. The activation and
deactivation of the valves are not subject to timers, but rather only a hysteresis that is equal to
the set point and the diff erential of the step (in fact the valve performs the same function as a
hermetic compressor).
r05=3: direct correspondence between the digital inputs and the compressor relays (condensing
units only).
- Type of compressor control
r06:
This parameter is used to set the logic for maintaining the set point:
r06= 0: proportional on inlet
r06= 1: proportional on inlet + dead zone (see Dead zone, below)
r06= 2: proportional on outlet
r06= 3: proportional on outlet with dead zone
r06= 4: on outlet by time with dead zone (see timed outlet temperature control)
DEAD ZONE
The dead zone essentially shifts the proportional band from the set
point by the value set for the parameter r07.This parameter is valid in
all confi gurations if enabled (for r07

0: dead zone set and enabled).
Key Figure 5.b.c:
r06: enable the dead zone (enabled if r06=1 or 3)
r07: dead zone
r01: cooling set point
r02: cooling diff erential
In chiller (cooling) mode, the dead zone moves the cooling proportional band above the set
point by the value r07.
Key Figure 5.b.d:
r06: enable the dead zone (enabled if r06=1 or 3)
r07: dead zone
r03: heating set point
r04: heating diff erential
In heat pump (heating) mode, the dead zone moves the heating proportional band below the set
point by the value r07.
Outlet temperature control by time r06 = 4 (only chiller)
This type of control is based on the need to maintain the outlet temperature as constant as
possible, despite the load being variable or the reduced inertia of the system.
The logic has the aim of keeping the temperature inside the dead zone.
If outside the zone, the compressors will be activated with the logic described below, so as to
return inside the dead zone, neither too quickly (using an integral or derivative), nor too slowly,
with fi xed time
logic. There are two logical times involved: the activation time and deactivation time.
- Dead zone diff erential
r07:
( see dead zone)
- Activation delay at lower limit of r07 (if r06 = 4)
r08:
The value set is used in the control algorithm (see timed outlet temperature control) as the
maximum time (at the start of the diff erential) for the activation of the compressors.
- Activation delay at upper limit of r07 (if r06 = 4)
r09:
The value set is used in the control algorithm (see timed outlet temperature control) as the
minimum time (at the end of the diff erential) for the activation of the compressors.
Activation time (cooling)
The activation time is not a set parameter, but rather the combination of two set parameters, that
is, r08 and r09. When the temperature leaves the dead zone, the activation time is equal to r08,
while at the end of the diff erential r02 the activation time is equal to r09.
Inside the diff erential r02, the activation time varies linearly between r08 and r09.
This means that as the temperature moves away from the set point, the times are reduced and
the esponse of the process becomes more dynamic.
- Deactivation delay at upper limit of r12 (if r06 = 4)
r10:
The value set is used in the control algorithm (see timed outlet temperature control) as the
maximum time (at the set point) for the deactivation of the compressors.
- Deactivation delay at lower limit of r12 (if r06 = 4)
r11:
The value set for this parameter is used in the control algorithm (see timed outlet
temperature control) as the minimum time (at the end of the deactivation diff erential) for the
deactivation of the compressors.
Fig. 5.b.c
Fig. 5.b.d
Fig. 5.b.e
activation time
temperature
time
dead zone comp. act.
diff erential