Analytical Industries GPR-2900 Series Oxygen Analyzer - Manual (Page 13)

Advanced Instruments Inc.
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4. To connect to an active relay or “fail safe”, connect the live cable to the common terminal C and the secondary cable to the
normally open NO terminal.
5. To break the connection upon relay activation, connect the secondary cable to the normally closed NC terminal.
6. Insert the stripped end of the cables into the appropriate terminal slots assuring no bare wire remains exposed that could
come in contact with the back panel of the analyzer enclosure.
7. Tighten the terminal screws to secure the wires of the cable.
Danger: While connecting the cables to the relay terminals, ensure there is no voltage on the cables to prevent electric shock
and possible damage to the analyzer. Caution: Assure the stripped wire ends of the cable are fully inserted into the terminal
slots and do not touch each other or the back panel of the analyzer enclosure.
Alarm Relays
Alarm 1 and Alarm 2 represent two threshold type alarms that can be configured in the field from the analyzer’s menu driven
LCD display as follows:
¾ Establish independent set points
¾ Either Hi or Lo
¾ Either On or Off (enabled or disabled)
¾ Both temporarily defeated using a user entered ‘timeout’ period (normally minutes)
The alarm set point represents a value. When the oxygen reading exceeds (high alarm) or falls below (low alarm) the alarm set
point, the relay is activated and the LCD displays the alarm condition. When activated the alarms trigger SPDT Form C non-
latching relays @ 5A, 30VDC or 240VAC resistive. To prevent chattering of the relays, a 2% hysteresis is added to the alarm set
point. This means that the alarm will remain active until the oxygen reading has fallen 2% below the alarm set point (high
alarm) or risen 2% above the alarm set point (low alarm) after the alarm was activated. Aside from being totally defeated in the
Alarm Bypass mode, the timeout feature is useful while replacing the oxygen sensor or during calibration when the oxygen
reading might well rise above the alarm set point and trigger a false alarm.
Note: When making connections the user must decide whether to configure/connect Alarm 1 and Alarm 2 in failsafe mode
(Normally Open – NO – where the alarm relay de-energizes and closes in an alarm condition) or non-failsafe mode (Normally
Closed – NC – where alarm relay energizes and opens in an alarm condition).
Power Failure Alarm
A dry contact rated at 30VDC @ 1A is provided as a power failure alarm that activates when power supplied to the analyzer’s
circuits is unacceptable. The contact is normally closed but opens when the power to the analyzer is switched off or interrupted
and cannot be disabled.
4-20mA Signal Output and Range ID
The analyzer provides a 4-20mA full scale fully isolated ground signals for external recording devices. The integral IC on the
main PCB provides 4-20mA fully isolated signals for output and range ID. The 4-20mA current output is obtained by connecting
the current measuring device between the positive and negative terminals labeled OUTPUT 4-20mA. To check the signal output
of the 4-20mA E/I integrated circuit connect an ammeter as the measuring device and confirm the output is within +0.1mA of
4mA. A finer adjustment of the zero offset of the 4-20mA converter can be provided by a potentiometer mounted on the main
PCB Assembly. Consult factory for instructions
For range ID the output of 4mA, 8mA, 12mA, 16mA, 20mA correspond to the most sensitive to least sensitive analysis range.
Caution:
The integral 4-20mA converters are internally powered and do not require external power. DO NOT supply any
voltage to any of the two terminals of the 4-20mA converter.