8.3 Electrical components
Electrical components and safety equipment
Pressure switch cooling cycle HP and LP
There is a high pressure switch (HP) in the hot gas
line within the cooling circuit to for switching off the
chiller in the event of insufficient heat dissipation. A
low pressure switch (LP) in the suction pipe or in
the compressor switches off the chiller if the fill
level for the refrigerant is too low.
Differential pressure switch
The differential pressure switch is installed parallel
to the evaporator in the medium cycle. It measures
the pressure differential between the inlet and
outlet pressure and switches the unit off when the
flow rate drops below the minimum flow volume or
with extremely large medium flow rates.
Condenser fan thermal contacts
The condenser fan's thermal contacts prevent
overheating of the motors.
Compressor thermal contact
The thermal contact is located within the com-
pressor and limits its hot gas end temperature.
Phase sequence relay
The phase sequence relay controls the direction of
rotation for the power supply. The controller will not
be enabled if the direction of rotation is wrong.
Probe B4 medium inlet
The probe is located at the unit's medium inlet
(system return flow). It serves to capture the cur-
rent temperature to control the target value.
Probe B7 medium outlet
The probe is located at the unit's medium outlet
(system inlet). It serves to capture the current tem-
perature and regulate the anti-freeze protection
temperature.
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Leak testing
The leak test is carried out after the connection
has been made.
1.
Flush the system twice with tap water.
2.
Clean the sieve insert on the dirt trap.
3.
Fill the system with water again and bleed
the unit at the manual bleed valves.
4.
Adjust the test pressure to at least 200 kPa
(2.0 bar).
5.
Check the connections after a period of at
least 24 hours for leaking water. If water is
visible, the connection has not been estab-
lished properly. Tighten the connection or
establish a new connection.
6.
After a successful leak test, remove the
excess pressure from the medium piping if a
water-glycol mixture is used or adjust the
non-circulating pressure to the required
system pressure.
REMKO KWE
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