Principle Of Operation; Operating States; Monitoring Mode - Honeywell Satellite XT 9602-0200 4-20 mA Operation Manual

This section provides basic understanding of the instrument and its operation.
1.1

Principle of Operation

The Satellite XT is a gas monitoring instrument especially designed for continuous
surveillance of hazardous gas concentrations. The instrument is designed to interface with
standard (0) 4 ... 20 mA alarm or control systems.
Target gas and measuring range depend on the type of sensor chosen. The sensor comes
with the specific data in its internal data memory. When a new sensor is inserted, these
data are loaded into the instrument's internal memory.
Satellite XT versions 4-20 mA and 4-20 mA/R use electrochemical sensors for the
surveillance of toxic and corrosive gases at TLV levels (TLV = Threshhold Limit Value).
The sensor output signal is amplified electronically, digitised and the resulting
concentration value is transmitted to the communication network.
Satellite XT versions 4-20 mA/C and 4-20 mA/C/R are used for monitoring combustible
gases and vapours. These instrument versions use catalytic sensors and are factory
calibrated for methane in air mixtures with concentrations up to 5 %-vol. (100 % LEL Lower
Explosion Limit). The sensor output signal is amplified electronically, digitised and the
resulting concentration value is transmitted to the communication network. To allow the
surveillance of a variety of other combustible gases, a correction factor called "K-factor"
can be entered.
Satellite XT versions 4-20 mA/R and 4-20 mA/C/R include the relay option and provide
3 single-pole double-throw relays for activation of external alarm devices. When the actual
gas concentration exceeds the alarm levels, the instrument will activate the appropriate
alarm relay and display an according message. A relay will also be activated in case of an
instrument fault.
1.2

Operating States

There are four different operating states for the Satellite XT, Monitoring Mode,
Maintenance Mode, Warning Condition, and Diagnostics. Depending on the selected
operating state, the green status LED is either on, off, or flashing.
1.2.1

Monitoring Mode

The Monitoring Mode is the instrument's standard operating mode.
The green LED located above the <set> key is on.
In the Monitoring Mode, the instrument continuously monitors for hazardous gas
concentrations and checks for alarm levels and instrument faults.
The instrument's self-diagnostics provide on-line preventive maintenance information
identifying electronics or sensor problems. For example a sensor selftest is performed
every 24†hours. The sensor selftest is not available with instruments using oxygen
sensors or catalytic sensors.
Satellite XT 4-20 mA Versions
Basic Operation – Section 1
1-1