Vaisala HMT310 - Manual (Page 61)

Chapter 4 _________________________________________________________________ Operation
VAISALA ________________________________________________________________________ 61
The prompt ">" appears when the heating period is over. However, the
transmitter outputs are locked to values measured before chemical purge
until the settling time is over.
Sensor Heating (Optional)
General
This function is optionally available only in transmitters with
HUMICAP ®
180RC sensor. It should be used only with the warmed
probe.
The sensor heating is recommended for the high humidity environments
where even a small temperature differences can cause water to condense
on the sensor. The sensor heating speeds up the recovery of the humidity
sensor from condensation.
Sensor heating starts up when the relative humidity of the measuring
environment reaches the RH value set by the user (RH limit). The user
can define the RH sensor heating temperature as well as the duration of
the heating.
After the heating cycle the humidity conditions are checked and new
sensor heating is performed if the predefined conditions are reached
again.
NOTE During the sensor heating the outputs are locked to the values measured
before the heating cycle.
NOTE Using sensor heating is not recommended when the transmitter is
powered with USB. For information on HMT310 operating voltages, see
section Power Supply Requirements on page 34.
HMT317 Fuel Cell Model Heating Settings
In the HMT317 fuel cell model, the probe heating temperature has been
set to the maximum in the factory configuration in order to minimize
condensation.
Sensor heating (XHEAT command) has also been enabled in the factory
configuration for the fuel cell option. See section Setting Heating
Parameters on page 62 for instructions on configuring the sensor heating
settings.