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3.10 Power supply control
Units may be supplied with devices for protection against incorrect connections of the phase sequence or voltage variations
outside the required limits during operation.
Protections consist in relays which output an alarm signal to one digital input in the controller through an electric contact
(the digital input concerned is shown in the wiring diagram).
The unit can be fitted with one relay to monitor correct phase sequence or one relay to monitor the power voltage or one
relay to manage both these functions.
Parameter "CF17" is set up at the factory depending on the featured relay to manage the relevant function.
3.10.1 Phase sequence
A dedicated relay is fitted to manage incorrect connection of the phase sequence to the unit. If the phase sequence is con-
nected incorrectly, the relay opens an electric contact that triggers alarm "AL55" on the controller display.
Incorrect connection of the phase sequence may be experienced upon unit installation or when work is performed on the
power supply line.
Power supply must be swithced off to the unit to make the connection correctly. The alarm is cleared as soon as the unit is
switched on again.
3.10.2 Min. / Max. voltage
The controller is designed to manage potential conditions where the variation of the power voltage to the unit experiences
a significant deviation from the expected values.
The parameters involved are shown in the table.
The values of the parameters are representative. In specific cases, different values can be set.
Parameter
Value
CF17
1
When the min. and max. voltage relay trips, the controller stops the unit and causes an alarm message to appear on the
display.
The value entered in parameter "CF17" and the supply or not of emergency power ("ultracap"), which is required to keep
the controller in operation, affect the alarm displayed and unit restarting.
If parameter "CF17" is set to "0", alarm "AL55" appears; if the parameter is set to "1", alarm "AL201" appears.
Both alarms are reset automatically as soon as power is restored to nominal values; normal unit operation, on the other
hand, is delayed by the time setpoint in parameter "CO30".
Where emergency power is available, the unit is restarted quickly ("Fast Restart" function).
3.10.3 Fast Restart
Activation of the "Fast Restart" function, provided that an "ultracap" is fitted to keep the controller electrically powered, is
designed to minimise as much as possible the delay experienced in restarting the compressors fitted in the unit.
This is possible because the controller starts counting the minimum time to OFF as soon as a switch-off is started due to a
blackout.
The controller detects problems with the main power supply through a digital input and manages them as alarms.
To protect the integrity of the compressors, the controller manages the maximum number of starts per hour by means of the
delay between two consecutive starts.
Quick restart after a blackout depends on the thermoregulation demand. As soon as the demand for cooling or dehumidifica-
tion is received, the min. off time and the time between two consecutive activations of one single compressor are shortened.
The "Fast Restart" function does not jeopardise the conditions of the compressors as it limits the number of quick starts
over the space of an hour or a day.
The parameters involved are shown in the table.
Daikin R32 Rooftops UATYA-B
ESIE21-02 – 2021.03
UM
Description
-
Power alarm management
3 Software functions
Service manual
47
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