In addition to the standard non-heated version, WMT700 can be preconfigured at the
factory according to your order:
• Heating for the transducers only
• Heating for both transducers and array arms
• Heating for body, transducers, and array arms
Make sure that the supply output power capacity is high enough especially when
transducers, array arms, and sensor body are equipped with heaters. Also, note that there
are individual connections for applying the heating voltage.
3.9.1 Heated Transducers
The heating functionality has a thermostatic control with temperature sensors in each
transducer. The control function keeps the transducer temperature above 0 °C and adds
heating power when necessary. Therefore, heating is only activated when there is a risk of
ice build-ups. If a sensor is blocked, WMT700 increases the heating power to melt the ice
and returns to lower power after a period of time.
You cannot change the heating parameters, but you can enable or disable the heating
functionality with
configuration parameters. When heating voltage falls below 18 VDC, an
alarm is raised. Heating is automatically disabled if heating voltage falls below 15 VDC.
Regardless of heating voltage, the maximum heating power is limited to 40 W and the
average heating power is limited to 30 W. The maximum power control is achieved by
automatically sequencing the transducer heaters depending on a heating voltage. At low
heating voltages, all the transducers are heated simultaneously. At mid-range, two of the
transducers are heated. At high voltage end, a single transducer is heated at a time. A pulse
width modulation (PWM) scheme is used to control the average heating power.
3.9.2
Heated Transducers and Arms
In addition to heated transducers, the array arms can also be heated, which prevents ice
build-up on the arms.
The functional principle is the same as with the heated transducers only, but the maximum
heating power is limited to 200 W and the average heating power is limited to 150 W.
Chapter 3 – Functional Description
49
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