Myron L 767 - Manual (Page 11)

Operating Procedures
3.2 MODEL 767 STANDARD AND OPTIONAL FEATURES
This section describes the standard and optional features of the
Model 767 Conductivity Monitor/Controller. (Refer to Fig. 3-1.)
Power Supply
The standard Monitor/Controller has a single power supply that
provides voltages for all circuit functions. It may be configured
for either a 110 VAC or a 220 VAC supply.
Conductivity
The conductivity circuit is designed as a three range device with
extremely accurate tracking between ranges. It receives raw
conductivity and temperature information from the Cell and
translates this into a voltage that may range from 0 to + 10 VDC.
This is the Recorder output. The Recorder output signal
represents the conductivity of the fluid at 25
° C. This signal is
available at terminals TB1-6 & 7
Meter Drive Section
The 0-10 V signal is also taken to the display section where it is
used to drive the analog meter.
Alarm Section and Relay
The alarm circuit compares the signal from the conductivity
circuit with a “set point” signal controlled by the user. The user
may check the current set point by pressing the “SET POINT
CHECK” switch on the front panel. This feeds the set point
signal to the Meter Drive section, which then displays the set
point on the meter.
Normally, if the conductivity signal becomes greater than the set
point signal, the alarm relay will be energized. The user may
adjust two jumpers that will cause the alarm relay to be
energized when the conductivity signal is less than the set point
signal.
Options:
03: the “03” option replaces the single Cell with three
separate Cells and a switch that allows you to switch
between each Cell.
420D: The “420D” option replaces the standard 0-10 V Recorder
output with a completely isolated 0-10 V output. In
addition, a 4-20 mA current loop output is available at
terminals TB1-4 & 5. These circuits have their own
completely separate power supply.
DP: The “DP” option adds a second alarm circuit (Alarm B),
which is identical to the first.
RM: The “RM” option adds circuitry to drive a remote 1 mA
analog meter movement.
3.3 SETUP PROCEDURES
These Setup procedures cover (1) setting the alarm circuit set
point(s), and (2) converting the alarm circuit to trigger on a
decreasing reading.
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