C0210101-07-16-EN
5.2
Evaporator / recuperator hydraulic circuit diagram
(See fig. 1 page A1)
6
CONNECTION OF THE COOLING CIRCUITS
When designing and laying the cooling circuits of a two-section plant, the following must be kept in mind:
The pipes must be positioned so that they are easily accessible for maintenance.
The load losses of the cooling circuits reduce the efficient cooling power and increase the power absorbed by the compressor.
Lubricating oil must return to the compressor with the same flow rate in all operating conditions, in order to guarantee correct lubrication. For
this purpose, the following instructions should be complied with:
- horizontal stretches must have a minimum slope of 0.5% in the direction of refrigerant flow;
- in vertical stretches fit suitable oil collection wells to facilitate flow (siphon);
- in particularly long stretches of piping fit an oil separator along the compressor delivery pipe;
The cooling circuit must always be clean, dry and free from any kind of contaminating substance.
Provide a liquid line with a suitable diameter in order to prevent gas from being present upstream of the thermostatic valve.
Liquid must never be allowed to enter during compressor suction.
Expansion of the copper piping must be appropriately calculated.
Absorption of expansion must be guaranteed by joints or achieved with stretches of U or L bends.
The brackets foreseen for the lines must support their weight and allow correct alignment.
To limit propagation of vibrations, which shorten the life-span of the cooling lines and make the plant run more noisily, fit flexible joints and
resilient brackets.
The liquid line must be suitably insulated.
Check that any liquid receiver contained in the machine is suitably large for the entire plant.
Check that any safety devices on the machine are suitable for the whole system; fit extra safety devices if necessary.
Use copper pipes of a thickness that is appropriate for the pressure involved.
If two evaporators run parallel in the circuit, siphons must be used to prevent oil from collecting in the evaporator that is not in use.
If the condenser is installed remotely from the compressor a siphon and a check valve must be fitted in the delivery line at the level of the
compressor, to prevent liquid from back-flowing during shut-down.
The condensing unit must keep the condensation pressure stable in order to allow the thermal expansion valve to work as best as possible.
If using R134a, R407C, R404A and R410A or other refrigerants that are not compatible with mineral oils, specifically designed and tested
accessories must be utilised.
The Declaration of Conformity and CE marking of the system pursuant to applicable European Community Standards and Directives
shall be issued by the system manufacturer, as shall its warranty.
7
ELECTRICAL CONNECTIONS
7.1
Electricity supply
The specifications of the mains power supply must comply with EN 60204-1 and the local regulations in force and be sufficient for the absorption
requirements of the unit indicated in the wiring diagram and on the data plate. Mains voltage must correspond to the rated value +/- 10% with a
maximum phase difference of 2%. The unit must be connection to a three-phase TN(S) type electric power supply. Should the installation of a
circuit breaker be envisaged in the electrical system, it must be type A or B.
Refer to local bylaws. Only power the system if the hydraulic circuit is charged.
7.2
POWER CONNECTIONS
Install an overload cut-out device, not included in the supply, on the supply line of the switchboard in compliance with the regulations in force.
Supply the unit switchboard with a cable of a diameter suited to the absorption capacity of the machine indicated on the data plate. The control
circuit is shunted off the power circuit from inside the switchboard.
Do not touch hot and/or sharp surfaces. It is forbidden to lay electric cables in positions that have not been specifically identified.
The supply must never be disconnected, except during maintenance operations, in order to guarantee operation of the compressor crankcase
heater and any anti-freeze resistances on the heat exchangers.
7.3
Control circuit interlocking
In order for the guarantee to be valid:
connect the calibrated flow switch to the specific terminals of the control circuit (if not included in the standard supply)
connect the auxiliary pump contacts to the specific terminals of the control circuit (if present in the wiring diagram).
unit input connectors (remote ON/OFF, flow switch, pumps enable, etc.) must be clean and single contacts for each unit (never
make a parallel connection to more than one machine with a single enable).
It is advisable for the connection cables of the above safety devices to be laid separately from any power cables. Otherwise, screened cables
should be used. To make serial connections, use only screened cables with characteristic impedance of 120 ohm. The maximum length of the
cable that connects safety devices to the farthest away unit must not exceed 1000 metres.
These devices must be connected to the first unit by a single serial cable, which then goes on to connect subsequent units. The screens of each
stretch must be connected to each other but not to the unit terminal block. One of the ends of these screens must be grounded.
If the remote ON/OFF control is used, cables must be laid following the same method as the flow switch cable.
Moreover, for remote ON/OFF control from external contact or from the serial protocol control, the following minimum times must be complied with:
Delays between 2 subsequent start-ups: 15 minutes
Delay between shut-down and start-up: 3 minutes
Furthermore, the pump must be operated for at least 1 minute before starting the unit and be switched off 1 minute after the unit is shut
down, otherwise the guarantee will be considered null and void.
7.4
INPUT VOLTAGE PHASE DIFFERENCE
Do not operate the electric motors when the voltage phase difference is greater than 2%. Use the following formula to check:
Max voltage difference from the average
% difference = ----------------------------------------------------------- x 100
average voltage
24