LCX
RG66010687_rev.00
17
5.5
SAFETY DEVICES ON THE HIGH-PRESSURE SIDE
Cooling circuit safety devices are provided on each refrigerant circuit according to the volumetric capacity
of the compressors installed, as prescribed by Directive 97/23 (PED); in particular, with respect to
equipment design, this Directive requires manufacturers to abide by the technical standard nearest to the
type of object produced; in the case of chillers designed for air-conditioning or liquid cooling systems,
standard UNI EN 378-2 is taken into consideration.
According to this standard, for refrigerant mass flow rates of up to 25dm3 per circuit only one pressure
limiting device is required; beyond this limit 2 must be applied. Practically speaking, these are safety
pressure switches designed to protect the cooling circuit in a cascade fashion.
What is meant by cascade protection is illustrated in the figure:
…where pressure switch 1 is set at the “PS” (maximum admissible pressure) of the system, while
pressure switch 2 will have the setting = PS x 0.9 in accordance with the reference technical standard.
6 ELECTRICAL
CONNECTIONS
6.1
GENERAL INFORMATION
Before carrying out any work on electrical parts, make sure the power supply is
disconnected.
Check that the mains electricity supply is compatible with the specifications (voltage, number of phases,
frequency) shown on the unit rating plate.
The power connection is made by means of a three-core cable plus neutral and earth cable or single-
core cables (one per phase) + earth according to the minimum section sizes specified in the wiring
diagram, which is an integral part of the documentation accompanying the chiller; the diagram code also
appears on the rating plate inside the compressor compartment.
The size of the cable and line protections must conform to the specifications provided in
the wiring diagram.
The supply voltage may not undergo fluctuations exceeding ±5% and the unbalance between phases
must always be below 2%.
Pressure switch 1
Cut out
Pressure switch 2
Cut out
Cut in
Cut in
