51-616 Echotel Model 350/351 Ultrasonic Non-Contact Level Transmitter
14
NOTE: These values are read only parameters and cannot be
changed by the operator. They are for reference use only, how-
ever, in the event of a question or problem with the 350/351,
an authorized representative or service technician will request
the values displayed in this menu. Become familiar with this
Service Menu and the corresponding instructions in the event
of the need to access this Special Menu.
3.0
Reference Information
3.1
Description
Model 350/351 non-contact ultrasonic transmitters detect
level in a wide variety of liquid level applications. The non-
contact sensor may be mounted integrally or it may be
mounted up to 100 feet (30 m) from the micro-processor-
based electronics. All parameters are entered by means of an
easy to use menu-based keypad housed within the unit.
3.2
Principle of Operation
Pulses generated by the microprocessor-based electronics
are directed via the sensor to the liquid surface. The
returning echo signal is detected by the sensor. The micro-
processor amplifies and converts the signal into a digital
representation of the distance from the reflecting surface.
A 4–20 mA output current loop is supplied providing
the monitored level data to external control devices. All
operating parameters are entered via three tactile-feedback
push buttons and displayed on a four character LED
display located under the transmitter cover.
3.3
Troubleshooting
3.3.1 Loss (
LOSS
) Displayed
1. The transmitter will display
LOSS
when the level falls below
the selected range value. Signal maintains fail-safe selection
and will return to normal output when level returns to a value
within selected range. Increase range if this is not desirable.
2. Echo lost. Check for surface foam, vapors or non-vertical
(off center) mounting of sensor.
3.3.2 Output Not Tracking Level
1. Check for obstruction in tank causing false echo.
2. Incorrect calibration mode (
HEIGHT
/
DISTANCE
) Refer to
Section 2.4.1, Height or Distance Selection
on page 11.
If unit was set up in the
DISTANCE
mode, change to the
HEIGHT
mode to verify transmitter performance.
