30
ENG
“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018
9. ALARMS
9.1 Types of alarms
There are two types of alarms:
•
system: EEPROM, probe and communication;
•
control: low superheat, LOP, MOP, low suction temperature.
The activation of the alarms depends on the setting of the threshold and
activation delay parameters. The EEPROM unit parameters and operating
parameters alarm always shuts down the controller and cannot be reset.
All the alarms are reset automatically, once the causes are no longer
present, except for the “Emergency closing not completed” alarm, which
requires manual reset.
Example 1:
the board without display has the red
1
flashing when an
alarm is active. For EEPROM alarms, it stays on steady.
1
Fig. 9.a
9.2 Probe
alarms
The probe alarms are part of the system alarms. When the value measured
by one of the probes is outside of the range of measurement, an alarm
is activated. The alarm limits correspond to the range of measurement.
In the event of a probe alarm, the driver closes the valve, regardless of
digital input status, until the error is no longer present.
Example:
the display shows probe alarms A1 and A2 in sequence. The
superheat value has exceeded the maximum limit allowed, and this is
indicated by the two top segments.
GAS Type
Mode
Super Heat
GAS Type
Mode
Super Heat
GAS Type
Mode
Super Heat
Fig. 9.b
Minimum and maximum superheat limits
If a probe alarm occurs, it may be due to the superheat value exceeding
the allowed display range -5…55 K (-9 to 99°F). The display therefore
shows the probe alarm code (A1/A2) and:
1.
if the superheat value is less than -5K, the display shows the two
bottom segments;
2.
if the superheat value is higher than 55K, the display shows the two
top segments.
GAS Type
Mode
Super Heat
GAS Type
Mode
Super Heat
1
2
Fig. 9.c
9.3 Control
alarms
These are alarms that are only activated during control.
P
rotector alarms
The alarms corresponding to the LowSH, LOP and MOP protectors are only
activated during control when the corresponding activation threshold is
exceeded, and only when the delay time defined by the corresponding
parameter has elapsed. If a protector is not enabled (integral time= 0 s),
no alarm will be signalled. If before the expiry of the delay, the protector
control variable returns back inside the corresponding threshold, no
alarm will be signalled.
Note:
this is a likely event, as during the delay, the protection
function will have an effect.
Low suction temperature alarm
The low suction temperature alarm is not linked to any protection function.
It features a threshold and a fixed delay (300 seconds), and is useful in the
event of probe or valve malfunctions to protect the compressor using
the relay to control the solenoid valve or to simply signal a possible risk.
In fact, incorrect measurement of the evaporation pressure or incorrect
configuration of the type of refrigerant may mean the superheat
calculated is much higher than the actual value, causing an incorrect and
excessive opening of the valve. A low suction temperature measurement
may in this case indicate probable flooding of the compressor, with
corresponding alarm signal. The alarm is reset automatically, with a fixed
differential of 3°C above the activation threshold.
Par. Description
Def.
Min.
Max.
UoM
C8
Low suction temperature
alarm threshold
-50
(-58)
-85
(-121)
200
(392)
°C(°F)
9.4 Valve emergency closing procedure
The following description only applies if EVD mini is connected to the
Ultracap module.
In the event of a power failure, EVD mini can provide emergency
closing of the valve, thus preventing any refrigerant from flowing to the
compressor.
In this situation, the driver generates two alarms: E8 and E5. If the
procedure concludes successfully (the valve closes completely), alarm E8
is cleared, however alarm E5 continues until the Ultracap module is able
to power on the driver.
•
E8: failed emergency closing (incomplete closing alarm). Active
during the emergency closing stage and until the valve closes
completely, after which alarm E8 is cleared. If the closing procedure
is not completed (e.g. because the Ultracap module does not have
enough charge), when next restarting the controller, the user must
manually reset the alarm (pressing the PRG/SET button or setting the
corresponding parameter to zero via serial connection);
•
E5: emergency closing (emergency force closing alarm). This depends
on a controller power failure and indicates that the emergency
procedure is in progress.
Notes:
•
if the voltage measured falls below a certain threshold, the controller,
connected to the Ultracap module, can start the valve emergency
closing procedure;
•
during the valve emergency closing procedure, the display is switched
off to save energy (therefore the alarms may not be shown on the
display, or only shown for a brief instant);
•
if power returns during the closing procedure, alarms E8 and E5 are
reset and closing is completed in any case.
