User manual

µC
2
SE process chiller +030220416 - rel. 2.2 - 25.01.2013
6.4.4 Maximum operating time of compressor in tandem
(par. c09)
In the case of 2 tandem compressors, it must be prevented that a compressor of
the same circuit works over the time set (c09), if the other remains off. This to
prevent the oil in common from migrating over that allowed towards the active
compressor, thus preventing that the next start-up of the compressor remaining
unused (FIFO logic) causes serious problems due to poor lubrication. Therefore
the compressor 1 (or 2), if it must operate continuously, after time c09 will switch
off leaving the task to the other, which was off. This function considers the
compressor protections. A c09 value lower than a c03 value is ignored and the
compressors exchange after time c03.
6.4.5 Compressor partialization in high pressure mode
(par. P04)
The parameter enables or disables partialisation of the circuit in high pressure
mode. The function is valid if the unit is provided with tandem or partialized
compressors and pressure transducers. In the event of a high pressure alarm, i.e.
values over P18 (with hysteresis of 0.5 bar), the controller disables one power step
of the circuit of interest and waits for 10 seconds. When this interval has expired, if
the alarm is still active, the unit is stopped otherwise it continues to operate in
partialised mode. In this condition, the indication PH1 is displayed. This condition
remains active while the pressure does not drop below the value corresponding to
the maximum condenser fan speed (F05+F06). The unit re-enables the power step
below this limit.
6.4.6 Compressors rotation (par. r05)
The rotation of the compressors allows the operating hours to be balanced either
statistically, using FIFO logic, or absolutely, by counting the effective operating
hours.
Settings:
r05=0: rotation disabled. The customer can use compressors with different power
ratings according to the desired logic or manage the partialisation,
activating/deactivating them in proportional mode.
r05=1: rotation with FIFO logic for switch-on/off (the first to be switched on will be
the first to be switched off and vice versa). In this way the operating hours will be
optimised along with the compressor peaks, even if the compressor times will
always be respected.
r05=2: rotation with hours control. The compressors will have the same operating
hours, as the compressor with the least operating hours is always started first, again
observing the safety times. This does not however consider FIFO logic and does
not optimise the starts and stops;
r05=3: do not select.
Note: the FIFO or timed rotation logic is not valid in the event of
compressor partialised output.
6.4.7 Regulation type/ compressor use (r06, r07)
r07: neutral zone. The neutral zone moves the proportional band by r07 from the
set-point and is valid in all configurations, if enabled by parameter r06.
r06: compressors regulation type. This parameter allows to set the logic for
maintenance of the set-point.
6.4.8 Timed output with neutral zone (r06 = 4)
This type of regulation originates from the requirement to keep the output
temperature as constant as possible, in spite of the fact that the load is variable, or
the system inertia is reduced. The logic has the objective of maintaining the
temperature inside the neutral zone. If outside, the compressors are activated with
the logic described below, to return to neutral area, not too quickly (with integral or
derivative action) or too slowly (with fixed time logic).
Par. Description
Def Min Max U.M.
c09 Maximum operating time of compressor
in tandem
0 = function disabled
0 0 60 min
Par. Description
Def Min Max U.M.
P04 Enabling of compressor partialisation in
high pressure mode
0=Deactivated
1=Activated
2=Do not select
3=Do not select
00 3 -
Par. Description
Def Min Max U.M.
r05 Compressors rotation
0 = Disabled
1 = FIFO type
2 = Hours balancing
3 = Do not select
00 3 -
Par. Description
Def Min Max U.M.
r06 Type of regulation/compressors use
0 = Proportional Input
1 = Proportional Input + neutral zone
2 = Proportional output
3 = Proportional Output + neutral zone
4 = Timed output with neutral zone
0 0 4 -
r07 Neutral zone differential 2 1 50 °C/°F
r06 = 0: proportional inpu
t
ON
OFF
r01
B1
r02
CMP1
ON
OFF
r01
B1
r02
CMP1
CMP2
r06 = 1: proportional input + neutral zone
ON
OFF
r01
B1
r02
CMP1
r07
ON
OFF
r01
B1
r02
CMP1
CMP2
r07
r06 = 2: proportional output
ON
OFF
r01
B2
r02
CMP1
ON
OFF
r01
B2
r02
CMP1
CMP2
r06 = 3: proportional output + neutral zone
ON
OFF
r01
B2
r02
CMP1
r07
ON
OFF
r01
B2
r02
CMP1
CMP2
r07
Key
r01 Set poin
t
t
Time
r02 Differential B1 Evaporator input probe
CMP1/2 Compressor 1/2 B2 Evaporator output probe
r07 Neutral zone differential
22