Edgetech 2000 Series User Manual

Model2000 Series DewPrime
Dew Point Hygrometers
-----------Theory of Operation-----------
dissipated in the thermoelectric cooler can raise the
temperature of the Sensor base above + 1 00°C, if it is not
attached properly to an appropriate heat sink. If this
should occur , the thermostat in the Sensor base will
open rather thanrisk damaging the Sensor.
The second of these protection circuits also relates to the
high temperature operation for which the Model2000
Series ba s been designed. This protection circuitty
monitors the Senso r mirror temperature continuously
and automatically shuts off any current flow to the
Sensor thcnnoelectrics should the mirror temperature
exceed+1 00°C. Thi s can occm primaril y when the
Sensor is at a high ambient temperature , +50°C to
+ 1 00°C,and an automatic self-standardization cycle is
initiated which heats the mim>r surmce . This heating
could ca1lSe 1he mirror temperature to exceed+ 1 oooc
and damage the Sensor . However, thi s circuitry protects
against this possibility.
4.2.5 Display Cireoitry
The Model2000 Series is equipped with an 8-character
alphanumeric LED display allowing presentation of
numeric and alphanumeric information.
4.2.6 Track or Hold Circuitry
The Track or Hold circuitry provides (1) an analog dew
point temperature oUlpUt identical to the direct dew point
temperature output as l<mg as the system is controlling
on the actual dew point temperature, and (2) a steady
output coriesponding to the actual dew point value just
prior to an ABC cycle, during the entire cycle.The time
when the two outputs are identical is called the Track
mode; the time spent during the ABC cycle is called the
Hold mode. By attaching process control instrumenta-
tion to the output of the Track or old circuitry , rather
than to the direct output of the Sensor mirror PRT
readout ci:rcuitty, the mirror t.empelamre increase and
decrease that occur during the ABC cycle can be effec--
tively "lnasked during this period. This feature can be
disabled by turning HOLD off .
During the ABC cycle, initiated automatically at power
tum-on, the output of the Track or Hold circuitry will be
the ambient temperature at the time of power tum-on.
.- • c:' '
4-4

Edgetech 2000 Series Specifications

General

Brand	Edgetech
Model	2000 Series
Category	Measuring Instruments
Language	English