Refrigerant Charge And Electronic Control - CIAT EREBA ACCESS 017 T Manuel D'instructions

8 - REFRIGERANT CHARGE AND ELECTRONIC CONTROL

Undercharge
If there is not enough refrigerant in the system, this is indicated by gas
bubbles in the moisture sight glass.
There are two possibilities:
• Small undercharge (bubbles in the sight glass, no significant change
in suction pressure).
- After detection and repair the unit can be recharged.
- The replenishment of the charge must always be done in the cooling
mode, slowly introducing liquid refrigerant at the suction side, until
there are no bubbles in the sight glass.
• Significant undercharge (large bubbles in the sight glass, significant
drop in suction pressure). In this case:
- Completely drain the refrigerant charge, using a refrigerant recovery
unit. After detection and repair check the charge with the unit off,
drain the system and recharge the full amount of liquid refrigerant
(see Table I) on the suction and discharge side.
- The refrigerant container used must contain a minimum of 10% of
its initial charge.
CAUTION:
If brazing is to be done, the refrigerant circuit must be filled with nitrogen.
Combustion of refrigerant produces toxic phosgene gas.
Change the refrigerant after an equipment failure, following a procedure
such as the one described in NF E29-795 or carry out a refrigerant analysis
in a specialist laboratory.
IMPORTANT:
Never use the compressor as a vacuum pump.
Always add refrigerant via the suction line.
Refrigerant must be added very slowly.
Do not overcharge the system with refrigerant.
If the refrigerant circuit remains open for longer than a day after an
intervention (such as a component replacement), the openings must be
plugged and the circuit must be charged with nitrogen (inertia principle).
The objective is to prevent penetration of atmospheric humidity and
the resulting corrosion on the internal walls and on non-protected steel
surfaces.
Electronic control
Operation and control of all units is carried out via the electronic control.
The instructions supplied with the control include comprehensive
descriptions.
After use, check the user interface is properly inserted into its housing
and the cover is closed by means of the screw supplied. This way, the
electronic control and the unit are protected against any impacts and
atmospheric agents.
PRO-Dialog + electronic control
PRO-DIALOG + is an advanced numeric control system that combines
complex intelligence with great operating simplicity.
PRO-DIALOG + constantly monitors all machine parameters and safety
devices, and precisely manages the operation of compressor and fans
for optimum energy efficiency.
It also controls the operation of the water pump.
A powerful control system
The PID control algorithm with permanent compensation for the
difference between entering and leaving water temperature and
anticipation of load variations regulates compressor operation for
intelligent leaving water temperature control.
To optimise power absorption, the PRO-DIALOG + automatically re-
calibrates the set point of the entering water temperature based on
the outside air temperature to one of the two pre-set values (occupied
building and of an unoccupied building for example).
PRO-DIALOG + control is auto-adaptive for full compressor protection.
The system permanently optimises compressor run times according to
the application characteristics (water loop inertia), preventing excessive
cycling. In most comfort air conditioning applications this feature makes
a buffer tank unnecessary.
Clear and easy-to-use control system
The operator interface is clear and user-friendly: two LEDs and digital
displays allow the immediate control of the device operating data.
The menus offer direct access to all machine controls, including a history
of possible faults, for rapid and complete chiller fault diagnosis.
Extended communications capabilities
PRO-DIALOG + allows remote control and monitoring of the unit through
a wired connection: 7-8 x 0.5 mm² multiple cables. The cable should be
screened of the FROH2R or BELTEN 9842 type.
The screening should be grounded only on the electric unit panel board.
Functions available are start/stop, cooling/heating mode selection (only
EREBA ACCESS HT unit), power demand limit or dual set-point and
customer safety lock.
The system permits remote signalling of any general anomaly for each
refrigerant circuit.
Three independent time schedules permit definition of: chiller start/stop,
operation at the second set-point (e.g. unoccupied mode), and operation
at low fan speed (e.g. during the night).
This option also permits cascade operation of two units and remote
control via communication bus (RS 485 serial port).
EN - 13 EREBA ACCESS 17 - 40 T/HT
EN