RLE GD100 - Manual (Page 7)

CTS-M17 Installation, Operation and Maintenance Manual
B84450-001-000 RG May 12, 2005 6
1.6 Signal Range
The default gas range for the 4-20 mA signal is:
0 – 100 %LEL max = 500 %LEL
This range is adjustable. Both the 4 mA level and the 20 mA level can be
reassigned through the menu system. Note that this adjustment does not change
the measurement resolution.
IMPORTANT: The Signal Range is the applied range of the 4-20
mA signal. The Display Range is independent of
the signal range.
1.7 Optional Relay Package
Two relays can be supplied; single pole double throw (SPDT; Form C) 1 Amp. Dry
contacts only. Configuration allows set point adjustment for actuation point, dead-
band, and delays, increasing or decreasing concentrations. The relay settings have
the same range as the display, and are independent of Analog Signal Range.
1.8 Default Conditions
Default conditions are those conditions, which occur:
• During the one minute wait state on Power On.
• In Fault status.
• In menu tree.
In these situations the following conditions hold:
• Signal set at 4.0 mA (or 2 Volts on Voltage Output mode)
• Relays set to non-energized.
• Digital communication show 0 %LEL; no alarm status and 4 mA equivalent
signal.
1.9 Sensing and Calibration
Sensor type: Catalytic bead
1.9.1 Calibration
The sensor shows a linear response to gas and therefore the unit is straightforward
to calibrate. Two gases are needed for calibration: Zero gas (clean air) and an
appropriate span gas. Adjustment is by two potentiometers on the circuit board.