Unexpected voltage on a wind sensor SEN0170

Hello!
I've bought wind sensor SKU:SEN0170
It is connected to 17V power supply. The interesting thing is that when it is completely stopped it is still generating stable voltage signal approximately 0.4V which is about 2 m/s according to specification.
If I decrease input voltage output signal will also decrease but won't be zero.
So the question, is it a normal behavior for such sensor and I just need to take this error into account when implementing software logic or I did something wrong?
I've bought wind sensor SKU:SEN0170
It is connected to 17V power supply. The interesting thing is that when it is completely stopped it is still generating stable voltage signal approximately 0.4V which is about 2 m/s according to specification.
If I decrease input voltage output signal will also decrease but won't be zero.
So the question, is it a normal behavior for such sensor and I just need to take this error into account when implementing software logic or I did something wrong?