Carel easy, Руководство пользователя

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16
GB
easy/easy compact +030220791 - rel. 2.0 - 30.05.2007
The defrost may be called, but not activated, in the following
cases:
continuous cycle;
dripping (dd>0);
post-dripping ( Fd>0);
compressor protectors;
off status;
disabling from digital input(A4=2);
setting the time delay (d5>0) for the defrost function when the
instrument is switched on (d4=1);
direct control mode only without defrost (r3=1) or reverse (r3=2) (in
this case the defrost is not called);
defrost by temperature (d0=0, 1, 4) and temperature measured by the
defrost probe above the end defrost set point (dt).
The defrost ends correctly:
at the end of the pre-set time (see parameter “dP”);
when reaching the set temperature (dt).
When the defrost ends correctly, the dripping (equal to the time set for
parameter dd) and post-dripping (parameter Fd) phases start.
The defrost ends early:
from the keypad, pressing the DOWN button for 3 s (manual end
defrost);
due to an immediate external alarm “IA” ;
due to a dirty condenser alarm “CHt”;
by setting direct mode only without defrost (r3=1) or reverse (r3=2);
switching off ;
when requested from the supervisor;
from digital input (see parameter A4=2) (the defrost call remains
pending).
In these cases, the early end of the defrost is not followed by dripping
and post-dripping.
Important:
the defrost is only available in direct mode, that is, when parameters
r3=0 or A4=9 (the latter has priority over r3);
using parameter d0, and according to the model available, type of
defrost to be activated can be selected;
the defrost has priority over normal temperature control; it may also
have priority over the compressor protectors (see parameter d9);
during the defrost, the temperature display can be frozen (see
parameter d6);
the continuous cycle has priority over the defrost
Parameters for confi guring the defrost
dI: interval between defrosts
The defrost is performed periodically at a frequency of every “dI” (in hours
or minutes, see parameter dC).
The interval starts counting from the previous end defrost. If the time is
equal to 0 (dI=0), the defrost is not performed, except when activated
from the keypad, by digital input, from the supervisor or by time band.
During defrosts the temperature alarms are inhibited.
dt: end defrost temperature set point/defrost temperature threshold
with temp. control
For the models fi tted with end defrost probe, this parameter allows an
evaporator temperature to be set at which the defrost is stopped (the
evaporator temperature is measured by the defrost probe). The end
defrost temperature diff erential is fi xed at 1° C (defrost thermostat, d0=
4).
If, at the start of a defrost cycle, the temperature measured by the defrost
probe is greater than “dt”, the cycle is not performed.
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In the event of defrost probe failure, the controller performs a timed
defrost with a duration equal to the value set for “dP”. The same is true if
the end defrost set point can not be reached, the defrost is stopped after
a maximum time equal to the value of dP, and the error Ed is displayed (if
enabled by A8) and stays on until a correct defrost cycle is performed.
dP: maximum defrost duration
Determines the maximum duration of the defrost (in minutes or seconds,
see parameter dC). When defrost by time is set (d0= 2/3/4) dP represents
the eff ective duration of the defrost.
d4: defrost when switching the instrument on
Starts a defrost when switching the instrument on (d4= 1). This has
priority over the activation of the compressor and the continuous cycle.
Running a defrost when switching the instrument on may be useful in
special situations (e.g. frequent power failures).
Case 1: the system is subject to frequent power failures
In the event of power failures the instrument’s internal clock, which
calculates the interval between two defrosts, starting from zero, is reset.
If the frequency of the power failure were, in an extreme case, greater
than the defrost frequency (e.g. a power failure every 8 hours against a
defrost every 10 hours), the controller would never perform a defrost. In
this type of situation it is better to activate the defrost when the unit is
turned on, above all if the defrost is controlled by temperature (probe on
the evaporator), so unnecessary defrosts are avoided or at least reduced
in duration.
Case 2: Systems with many refrigeration units
In this situation, if the defrost on power-up is activated (d4= 1) after a
power failure all the units will start a defrost. This may cause overloads.
To avoid this, parameter “d5” can be exploited, which allows a delay to be
set before the defrost starts, a delay which obviously must be diff erent
for each unit.
2
d5 (3)
dP (3)
d5 (2)
dP (2)
dP (1)
unit 1
[d4(1)= 1]
ON
OFF
ON
OFF
ON
OFF
ON
OFF
unit 2
[d4(2)= 1]
unit 3
[d4(3)= 1]
1
Fig. 4.h
Key:
1
power-up;
2
voltage.
d5: defrost delay on power-up or when enabled by digital input
Represents the time which must elapse between when the controller is
turned on and the start of the defrost.
The digital input can be used to start a defrost from external contact (see
parameter A4=3); d5 represents the delay between when the defrost is
enabled, or called, and when it eff ectively starts.
The defrost from digital input can be exploited to perform defrosts in real
time when is the RTC option is not fi tted. Simply connect a timer to the
multifunction digital input. The defrost will be activated when the timer
contact is closed. In the case where more than unit is connected to the
same timer, it is recommended to set parameter d5 to delay the defrosts
to a diff erent time for each unit.
Furthermore, to avoid unnecessary defrosts controlled by the instrument’s