Description Of The Parameters - Carel µC2 User Manual

Type of unit Parameter h01
0= air/air
1= air/air heat pump (cooling/heating)
2= air/water Chiller
= air/water heat pump (cooling/heating)
4= water/water Chiller
5= water/water heat pump rev. on gas cooling
heating
6= water/water heat pump rev. on H O cooling
2
heating
7= Air-cooled condensing unit
8= Air-cooled condensing unit rev. on gas
9= Water-cooled condensing unit
10= Water-cooled condensing unit rev. on gas
example of antifreeze/outlet limit management
1
ON
OFF
A1 A1+A2
Key:
1. freecooling or comp 2. probe B2

5. DesCRIpTION Of The paRameTeRs

To modify the parameters, see chapter 4 "Parameters."
• Probe settings: parameters (/*) (see Table 4.a)
- Type of probe: from /01 to /08: enables the reading of the corresponding analogue input or sets the
function
• functions of the probes
Temp. control Antifreeze probe
probe 1 circuit
st
1 st circuit
B1 B2 (low outlet
temperature)
B1 B2 (low outlet
temperature)
B1/B2 single circuit B2
(B1/B5 two circuits)
B1/B2 single circuit B2
(B1/B5 two circuits)
B1/B2 single circuit B2
(B1/B5 two circuits)
B1/B2 single circuit B2
(B1/B5 two circuits)
B1/B2 single circuit B
(B1/B5 two circuits)
B1/B2 single circuit B2
(B1/B5 two circuits)
B B2
- -
- -
- -
- B
- Min/max voltage and pressure values
from /09 to /12: sets the minimum/maximum voltage and pressure for the ratiometric signal.
- Probe calibration
from /13 to /20: calibrates the corresponding sensor (from B1 to B8).
- Digital filter
/21: Establishes the coefficient used in the digital filtering of the value measured. High values for this
parameter will eliminate any continuous disturbance at the analogue inputs (however decrease the
promptness of measurement). The recommended value is 4 (default).
- Input limit
/22: Establishes the maximum variation that can be measured by the probes in one unit program cycle;
in practice, the maximum variations allowed in the measurement are between 0. 1 and 1.5 units (bars, °C
or °F, depending on the probe and the unit of measure) approximately every one second. Low values for
this parameter will limit the effect of impulsive disturbance. Recommended value 8 (default).
- Unit of measure
/23: Selects the unit of measure as degrees centigrade or Fahrenheit. When the parameter is modified,
the µC 2 automatically converts the values read by the NTC temperature probes B1, B2, B into the new
unit of measure; while all the other parameters set (set point, differential etc. ) remain unchanged.
• Antifreeze, auxiliary heater: parameters (A*)
- Antifreeze alarm set point (low ambient temp. for air/air units)
A01: This represents the temperature (antifreeze set point) of the water at the evaporator outlet below
which an antifreeze alarm is activated; in this condition the compressors corresponding to the
circuit in question are stopped, while the pump remains on to decrease the possibility of freezing. The
alarm is reset manually (or automatically, depending on parameter P05) only when the water temperatu-
re returns within the operating limits (that is, above A01+A20).
In the Air/Air units (H1=0,1) the value represents the low room temperature warning threshold; this
alarm, activated according to value read by probe B1 or B2 (depending on parameter A06) is signal only,
and is reset depending on the value of P05.
If probe B2 is placed in the outlet air flow (air/air units), A01 becomes the outlet limit, and if the outlet
probe reading (B2) < outlet limit (A1) then:
1. bypass waiting time A;
2. stop the compressors; if already off go to pt. 4;
. bypass waiting time A;
4. close damper with 50% duty cycle if FC active and the ambient temperature means damper open or
dead zone. If FC is not active go to pt. 6;
2
5. bypass waiting time A after having closed r28 twice (from the end of the last period);
6. If B2 < A1 the alarm "A1" is activated. The alarm reset depends on P5.
2
Cond. temp. Press probe Antifreeze
probe 1 circuit probe
st
2 nd evaporator 2 nd circuit
B B4 Not used
B B4 Not used
B B4 B6
B B4 B6
Not used Not used B6
B B4 B6
B B4 B7
Not used B4 B6
Not used B4 B6
B B4 -
B B4 -
B B4 -
B B4 B7
Cond. temp. Press. probe
probe 2 circuit
nd
B7 B8
B7 B8
B7 B8
B7 B8
Not used Not used
B7 B8
B7 B8
Not used B8
Not used B8
B7 B8
B7 B8
B7 B8
B7 B8
Table 5.a
µC - +0022071 - rel. 1.2 - 26.10.2007
2