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User Guide
6
Checking the System
6.1 Over voltage protection
Warning
Take care when viewing the Over voltage indicator as, if it is lit, high (pos-
sibly mains) voltages are present on the exposed terminals.
The Model FG Thermometer is provided with supply over voltage protection. An
over voltage condition is indicated by illumination of LED 1, inside the processor
(Refer to Fig. 6-1). The over voltage loop current is limited to 40mA.
To check the LED;
1)
Ensure that the thermometer is connected in a 4 to 20mA loop as shown in
Section 5.0.
2)
Unscrew the four screws in the lid of the processor and remove the lid.
3)
Refer to Fig. 6-1. If LED 1 is illuminated, an over voltage condition exists
and must be remedied as soon as possible.
Note
It is possible that, when over voltage levels are small or intermittent, the
signal loop current will be in error while the LED is not illuminated.
6.2 Using the TEST switch
Warning
Take extreme care when using the TEST switch, as high (possibly mains)
voltages are present on the exposed terminals.
The Model FG Thermometer is provided with a TEST switch. The location of the
switch is shown in Fig. 6-1. When the switch is set in the TEST position, the unit
is electrically self testing and will set its output to indicate 1275°C ± 3°C (Celsius
Models) or 2325°F ± 5°F (Fahrenheit Models).
Fig. 6-1 Location of 'TEST' switch, Emissivity adjustment and 'Over voltage' LED
0
0
Emissivity Adjustment
Fibroptic Model FG Thermometer
'Test' Switch
'Over Voltage' LED Indicator
Page 11
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