nVent RAYCHEM VIA-DU-20 Mode D'emploi page 7

• If it has recognised the possibility of a fall of freezing rain, the device switches on for 5 hours. If the warning has
come via the weather service, the five-hour period begins from the moment the logic status signal changed from 0
to 1. The heating is switched off as soon as the ground temperature reaches the threshold value or the five hours
have elapsed. If however, after five hours, the ground temperature and moist conditions are present for heating
to continue, the heating is not turned off, i.e. following the five-hour period the device continues to operate under
normal operating conditions.
• If the device is set for the local detection freezing rain warning, you should ensure that the base temperature is
lower than the 18-hour ground temperature value, since otherwise the temperature will never fall below the 18-hour
value and the freezing rain warning will not function.
• The reliability of the early recognition function heavily depends on the correct setting of the parameters. It is
possible that ice may build up on the surface or the device may come on unnecessarily.
This parameter* is used for setting the minimum rise in the air temperature in order to recognise the potential risk of
freezing rain after a lengthy period of cold weather.
*This parameter temperature is indicated only when "local detection" is selected.
This parameter* is used to set the value below which the air temperature must fall for a period of at least 18 hours.
If this condition is fulfilled and the temperature rises sharply, there is a risk of freezing rain. The heating will be
switched on to prevent the risk of freezing rain.
The OVERRULING parameter is used to configure the relevant logic input. If the parameter is set to 'OFF' the input is
not evaluated by the control device. The control device is not affected.
In the 'ON' setting the control device cannot switch the heating on for 10 min. if the input is or was short-circuited.
This prevents peakloads in buildings. If the input is still short-
circuited or has short-circuited again after 10 minutes have elapsed, the device cannot turn on the heating for another
10 minutes.
If the device is set to 'BMS' the heating output is remote controlled. If the input is short-circuited, the control device
switches the heating off. If the input is open, the device will switch on the heating in any event.
The sensor values of the ice indicator are not displayed and not evaluated.
This parameter allows you to select what status the heating timer should assume in the event of a fault. The 'OFF'
setting is recommended for all energy sensitive applications, whereas the 'ON' setting should be selected for safety
applications.
This menu option indicates the heating time in hours (H) and minutes (M).
Using the and buttons the counter can be reset
Range of settings:
Interval:
Default setting:
Range of settings:
Interval:
Default setting:
Range of settings:
Default setting:
Range of settings:
Default setting:
0.5K/h ... 4.0 K/h
0.5 K/h
2.0 K/h
–15°C ... –1.0°C
1.0 K
–1.0°C
OFF, ON, BMS
OFF
OFF, ON
OFF
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