Analog Inputs And Output; Analog Inputs - GE Hydran 201 i Instruction Manual

25. OK - System status indicator LED: This green LED confirms that the
Hydran 201Ti is operating properly and that the fail alarm relay is energized. It turns
off if a fail alarm condition is detected and if the fail alarm relay is de-energized.
26. HH - High-High alarm LED: This red LED is lit when a High-High alarm condition
is detected and the High-High alarm relay is energized.
27. H - High alarm LED: This red LED is lit when a High alarm condition is detected
and the High alarm relay is energized.
2.5

ANALOG INPUTS AND OUTPUT

2.5.1

Analog Inputs

The Hydran 201Ti uses three analog inputs:
• Gas level reading (supplied by the Hydran 201 sensor)
• Temperature of the H201 sensor (supplied by the sensor thermistor)
• Temperature of the heating plate (supplied by the heating plate thermistor)
All H201Ti's inputs pass in a first level of processing which has the following functions:
• To protect the H201Ti against interferences and surges
• To filter out (low-pass) the noise from signals
• To convert the signals in voltage
• To amplify the signals
Next, the signals go through an analog/digital converter so the microprocessor can use
them.
• Two calibration constants (offset and slope) are used to convert the signal from the H201
sensor.
• Three calibration constants (short circuit, open circuit and a mid-scale value) are required
to convert (nonlinear) the signals from the thermistors.
Part 17997 Rev. 6, March 2011
Analog Inputs and Output
2-13