Tekmar 1773 Manual

D 194.8
Ice and Snow Detector Type 1773
for the TF-E System
Introduction
In cooperation with the moisture and temperature sensors of the TF-E system, the 1773 Ice and Snow Detector
is used for early detection of ice and snow and for keeping the monitored surface or gutter free by switching on
a defrosting device. One or two sensors can be connected to the 1773 Ice and Snow Detector. The sensor
function (temperature and/or moisture monitoring) and other settings can be defined for each sensor
individually. The individual parameters and measured values can be diplayed and changed in the menu using
the display and three operating buttons. An LED shows the current operating state.
The sensor type 3354 (or its predecessor 3351) can be used for gutters, flat rooftops or satellite systems. Open
areas such as driveways or parking lots can be monitored with the sensor types 3355 and 3356 (predecessors
3352 and 3353), which resist mechanical load such as cars driving over them.
Most ice and snow detection systems use exposed metal electrodes. Their disadvantage is that these
electrodes can accumulate dirt, suffer from corrosion or get short circuited by external conductive objects.
Therefore their sensors need periodical maintenance work in order to avoid that environmental influences impair
the accuracy of moisture measurement.
The TF-E system takes advantage of the increase of thermal capacity due to moisture, i. e. the availability of
water in liquid or solid form (snow, ice) on the sensor. With the help of a patented measurement and evaluation
method, the temperature variation with regard to the sensor is used to detect moisture on the sensor surface.
This guarantees a maintenance-free and secure operation.
Content
1. Functions
2. Sensor mounting in open areas
3. Sensor mounting in gutters, on rooftops and on satellite
systems
4. Connection diagrams
5. Commissioning
6. Display and pushbutton functions
7. Operation, menu and error codes
8. Technical data, safety instructions
1. Functions
If the sensor temperature is below the defined critical temperature limit, the moisture control is activated. If
moisture is detected, the heating system is switched on. If not, the moisture is measured again periodically. At
the earliest when the defined minimum heating time has expired, the heating system is switched off again if
there is no more moisture on the sensor.
In addition to the limit value of the critical temperature range (0 to +5 °C) a lower value can be set between -5
and -20 °C. This is useful because in case of very low outdoor temperatures there will no longer be any dripping
melt water or snow. If snow falls despite the extreme temperature, it will be dry, light and not slippery. In such a
case the heating would not be powerful enough to completely melt the snow on the surface. Thus the danger of
slippery conditions would rather be increased if the heating were switched on.
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