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operation during the coldest times of the year.
To avoid this hazard:
a) Equip the chiller with suitable antifreeze protection devices,
available from the manufacturer as optional accessories;
b) Drain the system via the drain valve if the chiller is to remain
idle for a prolonged period;
c) Add an appropriate quantity of antifreeze to the water in
circulation (see table).
Sometimes the temperature of the outlet water is so low as to
require the addition of ethylene glycol in the following percent-
ages.
Outlet water
Ethylene glycol
temperature [°F]
(% vol.)
39.2
5
35.6
10
32
15
28.4
20
24.8
25
21.2
30
14
40
3.4.3 Expansion tank
To avoid the possibility of an increase or decrease in the vol-
ume of the fl uid due to a signifi cant change in its temperature
causing damage to the machine or the water circuit, we recom-
mend installing an expansion tank of suitable capacity.
The expansion tank must be installed on intake to the pump on
the rear connection of the tank.
The minimum volume of an expansion tank to be installed on a
closed circuit can be calculated using the following formula:
V=2 x Vtot x (Pt min - P t max)
where
Vtot= vol. circuit total (in litres)
P t min/max= specifi c weight at the minimum/maximum tem-
perature reached by the water [kg/dm3].
The specifi c weight values at different temperatures for glycol
percentage values are given in the table.
%
Temperature [°F]
glicol
14
32
50
68
0%
1.0024 1.0008 0.9988 0.9964 0.9936 0.9905 0.9869
10% 1.0177 1.0155 1.0130 1.0101 1.0067 1.0030 0.9989
20% 1.0330 1.0303 1.0272 1.0237 1.0199 1.0156 1.0110
30% 1.0483 1.0450 1.0414 1.0374 1.0330 1.0282 1.0230
!
Caution: When fi lling the system, take into account
the capacity of the expansion vessel as well.
English
If the ambient air temperature at the chiller is less than
-10°C then you must move the expansion tank to a pro-
tected ambient close on the water return side of the chiller.
The safety valve and bleed valve must remain at the chiller.
3.5 Electrical circuit
3.5.1
Checks and connections
!
Before carrying out any operation on the electrical system,
make sure that the appliance is disconnected from the electri-
cal power supply.
All electrical connections must comply with the applicable
Ambient
regulations in force in the country of installation.
temperature [°F]
Initial checks
28.4
1) The power supply voltage and frequency must correspond
23
to the values stamped on the chiller nameplate. The power
19.4
supply characteristics must not deviate, even for brief
14
periods, from the tolerance limits indicated on the electrical
10.4
diagram , which are +/- 10% for the voltage; +/- 1% for the
5
frequency.
2) The power supply must be symmetrical (the effective volt-
-4
ages and the phase angles of consecutive phases must be
equal). The maximum permissible voltage imbalance is 2%.
Connection
1) The electrical power supply must be connected to the chiller
using a 4-wire cable, comprising 3 phase conductors and an
earth conductor, with no neutral. For minimum cable section,
see par. 7.5.
2) Pass the cable through the cable entry on the rear panel of
the machine and connect the phase and neutral to the termi-
nals of the main isolator switch (QS); connect the earth wire
to the earth terminal (PE).
3) Ensure that supply cable has at its source protection against
direct contact of at least IP2X or IPXXB.
4) On the supply line to the chiller, install a residual-current cir-
cuit breaker with a trip rating of 0.3A, with the current rating
indicated in the reference electrical diagram, and with a short
circuit current rating appropriate to the short circuit fault cur-
rent existing in the machine installation area.
86
104
122
The nominal current In of the magnetic circuit breaker must
be equal to the FLA with an intervention curve type D.
5) Max. grid impedance value = 0.274 ohm.
Subsequent checks
Check that the machine and the auxiliary equipment are
earthed and protected against short circuit and/or overload.
!
Once the unit has been connected and the upstream main
switch closed (thereby connecting the power supply to the ma-
chine), the voltage in the electrical circuit will reach dangerous
PCW420-650
levels. Maximum caution is required!
3.5.2
General alarm
All the chillers are equipped with an alarm signalling system
(see electrical diagram), comprised of a switching free contact
in a terminal block: this may be used for the connection of an
external audible or visual alarm, or used to provide an input
signal for a logic control system such as a PLC.
3.5.3
ON/OFF remoto
All the chillers can be connected to a remote ON/OFF control.
See the electrical diagram for the connection of the remote ON-
OFF contact.
3.6 Water-cooled version (W)
In the water-cooled version, the chillers require a water circuit
that takes the cold water to condenser.
The water version chiller is equipped with a pressure regulating
valve at the condenser inlet, whose function is to regulate the
water fl ow in order to always obtain optimum condensation.
Preliminary checks
If the water supply to the condenser is by means of a closed
circuit,
perform all the preliminary checks listed for the main water
circuit (para. 3.3.1).
Connection
1) It is advisable to equip the cooling water circuit with shutoff
valves, enabling the machine to be cut out in case of mainte-
nance.
2) Connect the water delivery/return pipes to the special con-
nections located on the back of the unit.
3) If the cooling water is "expendable" it is advisable to equip
the circuit with a fi lter at the condenser inlet, in order to re-
duce the risk of the surfaces becoming dirtied.
4) If the circuit is of the closed type, make sure it is fi lled with
water and the air properly vented.
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