Teledyne 3300ZB operating instructions Operational Theory, Introduction, Zirconium Oxide Sensors

Trace Oxygen Analyzer Operational Theory

Operational Theory

2.1 Introduction

The analyzer is composed of three subsystems:

1.Analysis unit with zirconium oxide sensor(s)

2.Control unit with signal processing, display and controls

3.Interface unit, supplying signals between 1 and 2.

The analysis unit is designed to accept the sample gas and direct it to the sensitive surface of the zirconium oxide sensor.

The control unit processes the sensor output and translates it into an electrical concentration, which supplies the customer with range, alarm outputs, and a meter readout giving the trace oxygen level. It contains a microcontroller that manages all signal processing, input/output, and display functions for the analyzer.

The interface unit receives power from the control unit, and creates precision heater and bias voltages for the zirconium oxide sensor.

2.2 Zirconium Oxide Sensors

2.2.1 Principles of Operation

Teledyne’s zirconium oxide sensor is a miniature solid state

sensor. It uses a stabilized zirconia disc as an electrolyte with a sensing electrode (the cathode) and a counter electrode (the anode) on each side of the disc. The zirconia is heated to a temperature of about 500°C via a built-in heater. By applying a suitable reference voltage across the cathode and anode, the heated zirconia acts as an electrolyte which is capable of moving oxygen ions within its crystalline structure. This allows for the reduction of oxygen molecules reaching the cathode and the generation of a current equivalent to the amount of oxygen in a sample measured in parts per million (ppm).

Teledyne Analytical Instruments 5