Safety Elements - Carrier 30PA Installation, Operation And Maintenance Instructions

Ductable air-cooled scroll
chillers and heat pumps
11. S
AFETY ELEMENTS
Low pressure pressostat
Connected to the compressor suction, it will stop its operation when
the pressure at that point goes down below the tare value (caused by
obstructions in the circuit, excessive dirt in the fi lters, fan stop or ice
formation in the evaporator). It disconnects at 2 bar and it is automatically
reactivated.
High pressure pressostat
Connected to the compressor discharge, it will stop its operation when
the pressure at that point reaches the setpoint. Disconnects at 42 bar
and is reactivated automatically.
Magnetothermal protection switches line
They are located at the beginning of the power lines for the compressor
and motor fan to protect them.
Main door switch
By using a mechanical device, it impedes access to the electric panel
when the unit is with voltage.
Automatic switch in the control circuit
Magnetothermal switch that protects the operation circuit against
continuous surges as well as against high currents of short duration
(short circuits).
Water circulation pump control
For units that include a circulation pump, the electronic control times
its disconnection after the unit is disconnected.
The electronic control also activates a safety device in the event of
pump failure which detains the operation of the unit.
Water safety valve
30PAC/PHC units include a safety valve with a tare value of 4 bar (see
hydraulic diagrams) in the hydraulic circuit.
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Water circulation control
A differential pressure switch detains the
operation of the unit when it does not detect
water circulation.
Differential pressure switch
Water anti-freeze protection
This safety device is built into the electronic control. This is activated in
COOLING mode when the water outlet temperature is lower than the
set value. This causes the stop of the outdoor fan and the compressor.
Note: For operation with glycol water: consult.
Refrigerant anti-freeze protection
This safety device is built into the units' electronic control. It is activated
when, working in COOLING mode, the indoor refrigerant temperature
is lower than the setpoint value. This causes the stop of the outdoor
fan and the compressor.
Anti-freeze protection with heaters (optional)
Anti-freeze protection with fl exible electrical heaters around the pipe
lines of the hydraulic circuit to avoid their freezing. This optional is
recommended with negative temperatures.
Defrost control
This control's mission is to eliminate the ice that might possible form on
the outdoor coil when the unit is working in HEAT CYCLE.
The control runs a defrost cycle when, after the fi xed time has elapsed
for the compressor working, the temperature measured at the defrost
probe is below the one set for its beginning.
In the defrost operation, the outdoor fan is stopped and the cycle
inversion valve triggers the operation in cooling MODE. Next the outdoor
fan may be connected.
Safeties at the compressor
The scroll type compressor that these units as standard have the
following safeties:
- Non-return valve built into the compressor.
- Thermal protection in the compressor, which stops the operation of
the motor when there is excessive heating.
- Protection of the compressor discharge temperature through a klixon.