Components Management; Compressors; Four-Way Valve; Electronic Expansion Valve - Carrier 50FF Series Control Manual

12 - COMPONENTS MANAGEMENT

Important: All screens for the confi guration of the unit and all its
components are protected by level 2 or 3 passwords. To modify
these parameters, it is necessary to request the passwords.
The chapter 16. "List of control parameters" includes all control
parameters together with an explanation and the screen of the
Graphic terminal in which they are located.

12.1. Compressors

Rotation of the compressors
The control allows the rotation of the compressors to equal their
number of operating hours. With this function, activated by default,
the compressor which starts up fi rst is the one which has the least
number of accumulated operating hours.
From this moment, the type of rotation of the circuits will be:
● Grouped: First there connect all the compressors of the same
circuit.
● Equalized (by default) : First there connects an alone compressor
of every circuit. Once connected all the circuits there connects
the second compressor of every circuit.
Note: for units with an active recovery circuit, the operation of the
compressor will depend on the position of the outdoor air damper
and it will not enter into rotation with the other compressors.
Compressor timing
All of the compressors, including the one for the active recovery
circuit (optional), shall respect the following timings:
● Delay of the start-up of the outdoor fan with regard to the
indoor fan (t =30s)
0
This determines the minimum time that should elapse between
the start-up of the indoor fan and the start-up of the outdoor fan
in order to guarantee a stable airfl ow.
● Delay of the start-up of the compressor with regard to the
outdoor fan (t =10s)
1
This determines the minimum time that should elapse between
the start-up of the outdoor fan and the start-up of the fi rst
compressor to limit the simultaneous start-up.
Therefore for the start-up of the fi rst compressor it must pass:
t + t
0 1
● Minimum operation time (t
This keeps the compressor in operation during the period
selected. It is not allowed to be shut down unless there is a
failure in the circuit.
The minimum time of operation of the compressors must be
120 seconds (do not change).
● Minimum shut-down time (t
This determines the time that must elapse from the last shutdown
of the compressor before it can start up again.
● Time between start-ups of the same compressor (t
This sets the maximum number of compressor start-ups in
one hour.
● Time between start-ups of several compressors (t
This determines the minimum time that should elapse between
the start-up of a compressor and the start-up of the following
one. It limits the simultaneous start-up and the peaks of starting
current of an unit.
=120s)
2
=180s)
3
=300s)
4
=60s)
5
t
0
t
1
t
2
t
4

12.2. Four-way valve

In the heat pump units, there is a four-way valve per circuit which
allows the HEATING / COOLING operation mode of the unit to
be selected.
● Valve with voltage (N.O.): for operating in COOLING mode and
during defrosting (by default).
● Valve without voltage (N.C.): for operating in HEATING mode.

12.3. Electronic expansion valve

The "50FC" control board directly controls two unipolar stators for
electronic expansion valve (EVV).
The control manages the circuit overheating (SH setpoint). The
valve opens and closes depending on:
● The value measured by the suction temperature probe.
● The evaporation pressure on the circuit.

12.4. Outdoor circuit fans

Types of fans
The "50FC" control enables managing various types of outdoor
fans:
● 2-speed axial. In this case, it's possible to select, by means of
parameters, the pressures for the change in speed as well as
the fan disconnection time to implement this change. The fan
start is always carried out at high speed.
● Electronic. In this case, it's possible to select, using three
parameters, the maximum speed in COOLING and HEATING
mode (by default 100%), as well as the minimal speed (0%).
Operating mode
The outdoor fans will be in operation with the manufacturer's
settings whenever the compressors are in operation, except in
these cases:
● Disconnection is timed to the stopping of the compressor in 60
seconds both in COOLING mode (to reduce the condensation
pressure) and HEATING mode (to remove ice from the coil).
● Disconnection during defrosting, except when the defrosting is
started by low pressure, which will operate if the pressure rises
over the ON value and will disconnect if the pressure drops
below the OFF value.
Condensation and evaporation control
The control can manages the condensation pressure (in cooling
mode) and the evaporation pressure (in heating mode), with
AUTO setpoint, according to the outdoor temperature and the
circuit capacity (half or full).
indoor fan
outdoor fan
t
3
compressor 1
t
5
compressor 2
27