Airflow Sensor; Measurement Principle - E+E Elektronik VELOPORT 20 Manual

Manual
8

Airflow Sensor

8.1

Measurement principle

With the Hot Film Anemometer (HFA) an electrical resistor is
heated to a defined temperature. Airflow cools the resistor down
until the heat supplied and the heat lost are in balance. The higher
is the speed of the airflow, the higher the heat loss. A bridge circuit
compensates the influence of environmental temperature.
With the Constant Temperature Anemometer (CTA) the electrical
resistor is supplied with power in such a way that the temperature
of the resistor is constant. The power necessary to achieve this is
thereby a measure for the air velocity. High sensitivities can be
achieved using this method.
VELOPORT 20 english
page 38