Profroid SOLO 50 Notice D'instructions page 29

Electrical protection
For electrical motors, this must conform to standards in force and must be set according to the maximum current for the speed
used.
For electric heaters, the protection is linked to the neutral circuit:
- Neutral TT : Differential circuit breaker 300 mA.
- Neutral IT : Fuses.
- Neutral TN : We advise the installation of a differential circuit breaker 300 mA.
Where the neutral is distributed, heaters are connected at the star point.
(Note: on some industrial models, neutral is located on the opposite side of the cooler).
3- START-UP OPERATIONS
PRELIMINARY CHECKS
Ensure that all the threads are fully tightened on fans (jolting during transportation could cause them to loosen).
Check also if there are any breaks in the piping. (breaks could occur during transportation).
LEAKAGE TESTING
Pressurise the whole system, including the cooler, using a neutral gas
minimum pressure of 10 bars and at a maximum
Important
: If the LP (low pressure) circuit is fitted with a safety valve (e.g.: on the suction accumulator) the test pressure on that
part of the circuit should be approx. 20% below the operating pressure of this valve.
Thorough leakage detection using a suitable detector should be carried out on the unit.
DEHYDRATION OF CIRCUITS
This operation must be carried out with all valves open (including solenoid valves) with connection to a vacuum pump of the HP and LP
sides.
The quality of drying should not be judged by the speed at which the level of vacuum is reached but on the effective time it
is held (24 hours at 0.7 mbar is a good standard).
The total increase in pressure during that period should not be more than 2.6 mbar.
The residual moisture in the system should be less than 20ppm.
When the installation is under vacuum, an insulation check of the motor should not be carried out nor should the compressors be
started before at least 1 bar of fluid pressure is reintroduced. (To prevent motor windings damage).
FAN CHECKS
Check that the fans are rotating in the correct direction, i.e. drawing on the coil.
Check the fans rotating direction.
Measure the current absorbed by each motor and compare with the nominal current (displayed), taking into account the network
current.
HEATER CHECKS
Check heating
Ensure that the currents passing through the three phases are identical and that there has not been an imbalance in the circuit. If
so, re-balance the circuit or replace the non-working heaters.
Heater insulation
Allow the heaters to warm up.
Cut off supply to these and very quickly take the insulation value on the heater contactor between the phase and earth.
If this is over 3K ohms when hot, it is satisfactory. If not, check where the
heaters.
DEFROST CONTROL
 Air Defrost
Sequences:
- Stop compressor, while keeping the fans running by means of the timer or the controller. preferably following a pump down to
drain the air cooler, but without creating a vacuum (the vapour acting as a conductor in a vacuum).
- Keep fans running during the full defrost
- Return to cooling by means of timer or control switch.
-
(Nitrogen) with a (non-liquid, non-colorant) tracer
pressure below 20.5 bars, isolating the LP (low pressure) switches.
breakdown of insulation is, or
at a
for deficient