6
kayden.com Online Store
CLASSIC
®
800 Product Manual
Introduction
IV. 4-20 mA ANALOG OUTPUT
The
4-20 mA analog output signal
corresponds to the
Thermal Signal LED Bar Graph
.
•
The 4-20 mA signal may be displayed either as forward-acting (ascending 4-20 mA) or reverse-acting
(descending 20-4 mA).
•
The 4-20 output can be configured to output either 3 mA (LOW) or 21 mA (HIGH) in a fault condition
(NAMUR NE 43).
•
When the CLASSIC is in Set Mode, the 4-20 mA Output is disabled and will default to LOW or HIGH.
Refer to the
Section 3, “View or Adjust the 4-20 mA Output Configuration (Forward or Reverse)”
or the
Classic 800 Series Quick Setup Guide
.
The Thermal Signal is
higher
(right-most LED illuminated) when the
sensor is submerged in a fluid
and decreases
when the sensor is
exposed to air or gas in a motionless state
(see Figure 5).
Thermal Signal
100%
0
Relay 1
Relay 2
Fault
Set Point 1
Set Point 2
Run Mode
Bypass
RUN
SET
1
2
CLASSIC
™
High Level
Set Point
Thermal Signal (%)
Time
Set Point
High Level
0
0
100
High Level
Interface
The Thermal Signal
changes
as the (interface) sensor is exposed to an
alternate fluid
which has a different rate
of
thermal conductivity
.
The CLASSIC 800 can be set up to detect the difference between most liquids when:
•
The
different rate of the thermo-conductivity
of the two fluids
is large enough
to detect.
•
There is little or no velocity, and the process media is in a stable motionless state.
Thermal Signal
100%
0
Relay 1
Relay 2
Fault
Set Point 1
Set Point 2
Run Mode
Bypass
RUN
SET
1
2
CLASSIC
™
Oil
Water
Set Point
Thermal Signal (%)
Time
Set Point
Water
Oil
100
0
Water
Oil
Figure 5 - Thermal Signal Submerged vs Dry
Figure 6 - Thermal Signal in Alternate Fluids
0
