Advanced Instruments Inc.
Electrical
Connections
The appropriate AC or DC power requirement must be
specified at the time of placing order.
Incoming power for the 100-250V AC powered analyzers is
supplied through a universal power entry module. A
standard computer type power cord (P/N A-1008) is required
for the universal power entry module. DC power cable must
be supplied by the user. A well grounded insulated power
cable is recommended to avoid noise resulting from
unwanted interference. Power consumption is approximately
7 watts.
Terminal blocks are provided for power failure, alarm relays
and signal output connections. A sensor bypass switch is
provided at the rear of the analyzer for troubleshooting the
electronics
Caution: Integral 4-20mA converters are internally powered
and do not require external power. DO NOT supply any
voltage to any of the terminals for 4-20mA signal output and
range ID, supplying power to 4-20 mA terminal will
permanently damage the 4-20 mA IC.
Procedure:
1.
As illustrated above the sensor, power and alarm relays and signal output connections are mounted on the PCB
with the screw type terminal protruding out for making external connectionsr.
2.
Use a small bladed screwdriver to loosen the appropriate terminal screws as illustrated above.
3.
Strip the wires of the cable no more than 3/16 inch.
4.
Connecting Relays as " 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:
Establish independent set points
Either Hi or Lo
Either On or Off (enabled or disabled)
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.
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