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This can be done in two different ways:
1. Local detection freezing rain warning
If the device is set to LOCAL DETECTION, i.e. local detection of risk of freezing rain, the
device will heat the surface as soon as it notices a sharp rise in temperature after a lengthy
period of cold weather.
The rise in air temperature is performed by an air temperature sensor which is delivered
together with the device.
The device can recognise a lengthy period of cold weather by means of a ground tempera-
ture sensor, if the ground temperature has been below a set value for 18 hours. See also the
sections on the rise in temperature and the low ground temperature for an 18 hour period in
the paragraphs relating to the following parameters.
2. Freezing rain warning via the weather service
With this function, the device waits for a logic signal sent from an additional device to the
terminals of the air temperature sensor. The additional device, which is not part of the
standard package, evaluates information from the weather service and converts these into
the relevant logic status.
The control device expects the following logic status pB«nals
Logic status
0
1
Instructions for early recognition of freezing rain
• 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.
* The air temperature is indicated only when "local detection" is selected.
8
Input in control device
open
short circuit
Range of settings:
Interval:
Default setting:
Range of settings:
Interval:
Default setting:
Reaction of the control device
Heating OFF (no risk of freezing rain)
Heating ON (risk of freezing rain)
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
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