Pressure And Prevent Alarms; Pressure Alarms From Pressure Switch; Low Suction Pressure From Pressure Switch; High Condensing Pressure From Pressure Switch - Carel PRK300L3FK User Manual

ENG
After having selected the 'generic' description, no other description can
be selected. In general, the descriptions are divided into four groups:
•
generic
•
others (overload, oil, high pressure , low pressure)
•
screw rotation
•
oil warning
After a description has been selected for a certain group, descriptions
from a diff erent group can not be selected for that alarm.
For example, generic only, or overload + oil, or rotation only or overload +
high pressure., etc. can be selected.
Each alarm will have one alarm screen, which will show all the descriptions
associated to that alarm.
Based on the number of alarms selected, the descriptions associated by
default are shown in the table below
Default descriptions based on the number of alarms
Number of alarms Descriptions
1 Generic
Overload
2
HP-LP
Overload
3 HP-LP
Oil
Overload
HP
4
LP
Oil
Overload
HP
5 LP
Oil
Oil warning
Overload
HP
LP
6
Oil
Oil warning
Rotation
Overload
HP
LP
7 Oil
Oil warning
Rotation
Generic
Note: for oil alarms, special management is available whereby the
alarm is interpreted as an oil level alarm. When the alarm is
activated, a number of attempts are made to restore the level for a set
time before the alarm is signalled and the compressor stopped; see
paragraph 6.6.1 for details.
If a modulating device is used for the compressors, further alarms
become available:
•
compressor inverter warning, common for the entire suction line,
when the device is an inverter
•
oil sump temperature alarm, high discharge temperature and oil
dilution, for Digital Scroll™ compressors
For each compressor, two alarm variables are sent to the supervisor, one
for each priority. As well as the alarm signal, the description of the alarm is
also sent to the supervisor, using the values shown in the table:
The supervisor can interpret the variables sent by pRack pR300 and
provide the correct description of the alarm.
pRack +0300025EN rel. 1.3 - 17.12.2015

8.3 Pressure and prevent alarms

pRack pR300 can manage pressure alarms from a pressure switch or
probe, according to the following diagram.
Alarms from pressure switch:
•
Low suction pressure
•
High condensing pressure
Alarms from probe:
•
Low suction pressure
•
High suction pressure
•
Low condensing pressure
•
High condensing pressure
One possible example for the low pressure alarms is shown in the fi gure:
LP
Pressostat alarm
In addition, the high pressure alarm features a prevent function, available
by manually overriding the devices as well as using additional functions,
such as heat recovery and ChillBooster.
Operation of the alarms and prevent function is described below.
8.3.1

Pressure alarms from pressure switch

The parameters corresponding to these alarms can be set in branch
G.c.a/G.c.b of the main menu.

Low suction pressure from pressure switch

The low suction pressure alarm from pressure switch has the eff ect of
stopping all the compressors without observing the various times,
therefore when the digital input confi gured as low pressure switch
is activated, all the compressors on the line aff ected are stopped
immediately.
This alarm features semiautomatic reset, and both the monitoring time
and the number of activations in the specifi ed period can be set. If the
Tab. 8.b
number of activations is higher, reset becomes manual.
In addition, the delay after which the alarm is activated on both start-up
and during operation can be set.
The delay at start-up only applies to unit start-up and not compressor
power-up.

High condensing pressure from pressure switch

The high condensing pressure alarm from pressure switch has the eff ect
of stopping all the compressors without observing the various times
and forcing the fans on at maximum speed, therefore when the digital
input confi gured as high pressure switch is activated, all the compressors
on the line aff ected are stopped immediately and the fans operate at
maximum output.
This alarm features manual or automatic reset, as confi gured by the user.
The delay after which the alarm is activated can also be set
76
Differential
Probe alarm
Fig. 8.a
Pressure