Safety Elements - Carrier 50EN Installation, Operation And Maintenance Instructions

Packaged rooftop units
10. S
AFETY ELEMENTS
Low pressure pressostat
When 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).
This pressostat disconnects at 2 bar and 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. It disconnects at 42 bar
and it is automatically reactivated.
Magnetothermals for line protection
They are located at the beginning of the power lines for the compressors
and motor fan(s) to protect them.
Safety at the compressor
Temperature probe for the discharge from the compressor to protect
the unit with discharge temperatures greater than 135ºC.
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).
Defrost control
This safety device is intended to eliminate ice which could accumulate in
the outdoor coil when the unit is working in the heating cycle. Defrosting
is carried out by the control depending on the value measured by the
sensor(s) on the outdoor coil(s) and the time set between defrosting
operations.
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Condensation and evaporation pressure control
This safety device, integrated in the control, enables managing the
outdoor fan(s) when the units are working in cooling mode with low
outdoor temperatures (condensation control) or in heating mode with
high outdoor temperatures (evaporation control). This aids the unit's
operation in all the seasons.
In the case of EC electronic fans, such as those that are found in these
units by default, speed control will be proportional based on the average
pressure measured by the pressure transducer(s) in the outdoor coil(s).
Anti-fi re safety
The electronic control can activate an anti-fi re safety device that
detains the unit when the return air surpasses a temperature of 60°C
(by default).
It cannot return to operation until the temperature has dropped to
below 40ºC.
Smoke detector (optional)
In accordance with standard NF S 61-961, this smoke detection station
uses a LED to indicate the installation status, and if the probe detects the
presence of smoke in the installation, it stops the operation of the unit.
The station is installed in the factory in the auxiliary electric panel
(except in models 200 to 360 which do not include this panel).
Smoke detecting station
Control of air fl ow
- The supply plug-fans (standard) adapt their speed to the average
fl ow measured by the differential pressure sensor and the value set
as a setpoint in the electronic control.
- For those units with centrifugal supply fans (optional), a differential
pressostat can be incorporated in order to measure the variation in
air fl ow. This pressostat allows the detection of fan belt breakages,
since the fan relay only detects operating faults that have arisen in
the motor. This pressostat is installed in the factory in the auxiliary
electric panel (except in models 200 to 360 which do not include
this panel). This safety device is mandatory for units with electrical
heaters and with gas burners if the unit does not have the supply
plug-fans.
Air inlet tube
Smoke detecting probe