Granville-Phillips Mini-Convectron 275 Series, Инструкция по установке, эксплуатации и обслуживанию, Страница: 21 / 52

Introduction
Mini-Convectron
®
Module with DeviceNet
®
Digital Interface 13
3.9 Theory of Operation The transducer is a convection enhanced Pirani gauge providing rapid
response, six decades of pressure transduction, stable calibration and good
accuracy. The R1 Pirani sensing element shown in Figure 3-5, is one leg of
a Wheatsone Bridge.
Figure 3-5 Gauge Tube Schematic
A temperature compensating network R2, forms the second leg of the bridge.
The temperature sensitive component of this network is mounted inside the
gauge tube envelope with the sensor. All other resistors of the bridge are
mounted upon the exterior electrical feed through pins of the gauge tube. Pin
4 serves as an electrical terminal for construction of the compensating
network R2, but no connection is made from the controller.
All materials have been chosen for ultra high vacuum service, corrosion
resistance and the gauge tube (without the electronics module) can be baked
to 150º C. The gauge tube envelope is type 304 stainless steel. All metallic
joints in the envelope are TIG welded. No solder is used within the
envelope. The following materials are exposed to vacuum; Type 304
stainless steel, Carpenter Alloy 52, Kovar, Kapton, gold plated tungsten and
borosilicate glass.
PIN 1
PIN 5
PIN 2
PIN 3
R1 R3
R4
R2