Teledyne GC-Pro/FID - Gas Chromatograph - Manual (Page 28)

Operational Theory GC-Pro FID
Teledyne Analytical Instruments 14
2.4.2 Anode Power Supply
The high voltage anode power supply components are mounted on
the anode power supply printed circuit board. High voltage regulation is
achieved through the use of series-connected zener diodes. The
simplicity of this circuit’s design can be attributed to the extremely low
current demand of the anode circuit. The positive output voltage is
nominally 125 volts. Output tolerance is ±10 volts from the specified
125 volts.
2.4.3 Flame Guard Circuit
A thermistor-controlled, transistorized switching circuit is employed
to operate a relay in the event of a flame-out condition. A panel indicator
light and fuel shut-off solenoid valve are operated by the relay to alarm
personnel that a flame-out condition has occurred. The fuel shut-off
solenoid valve stops the hydrogen flow.
2.4.4 Flame Ignition Circuit
The flame ignition circuit includes the anode-igniter electrode (in the
detector cell), a transformer, and processor controlled relay. The circuit
is automatically energized when the FID cools due to lack of flame.
If automatic ignition fails five times, there will be a message that
reports this, and the flame can be re-ignited by pressing the re-ignite
icon from the touch screen. See Figure 2-4 and Section 4.6.
Figure 2-4: Onscreen Re-Ignition Button