Analysis and Handling of Common Malfunctions in Ultrasonic Level Gauge

Ultrasonic level gauge is a digital level instrument controlled by a microprocessor. In measurement, ultrasonic pulses are emitted by sensors (transducers), and the sound waves are reflected by the liquid surface and received by the same sensor. They are converted into electrical signals by piezoelectric crystals, and the distance from the sensor to the measured liquid surface is calculated based on the time between the emission and reception of the sound waves. Due to the use of non-contact measurement, the measured medium is almost unrestricted and can be widely used for measuring the height of various liquid and solid materials. The following are common faults of ultrasonic level gauges.

1. Ultrasonic level gauge sensor does not work
Common faults: No operation after power on, no display, no sound from sensors
Fault cause:

① The power supply is not connected or the positive and negative poles are reversed;
② The working voltage is too low, the instrument does not work, or the working voltage is too high, and the ultrasonic level gauge is damaged.
Troubleshooting: ① Check the circuit and connect the wires according to the instructions;
② Contact the instrument manufacturer.
2. Common faults of ultrasonic level gauge values not changing: The ultrasonic level gauge displays a sound, but the number does not change with distance.
Reason for malfunction:

① The input working voltage is too low, and the ultrasonic level gauge is not working properly;
② The ultrasonic level gauge sensor or power driver is damaged.
Troubleshooting: ① Use a 12-24V DC power supply;
② Contact the instrument manufacturer.

3. The value of the ultrasonic level gauge jumps around
Common faults: display, sound, measurement values jumping or values not changing with distance
Reason for malfunction: ① The installation inclination of the ultrasonic level gauge is too large;
② Improper setting of pulse intensity leads to excessive residual vibration or diffraction;
③ Two or more ultrasonic level gauges are working simultaneously, causing mutual interference;
④ Excessive electromagnetic interference on site; ⑤ There are bubbles or debris on the liquid surface.
Fault handling: ① Adjust the sensor axis to be perpendicular to the target plane;
② Generally within a range of 1-3m, the emitted pulse intensity is 2-5;
③ Try to eliminate mutual interference;
④ Identify the source of interference and block it;
⑤ Eliminate bubbles and debris on the liquid surface.

4. Ultrasonic level gauge does not display
Common malfunction: The sensor produces a working sound, but the ultrasonic level gauge does not display.
Reason for malfunction: ① The display has been turned off;
② Once received high voltage, the display chip is damaged.
Troubleshooting: ① Press the B key to turn on the display;
② Contact the instrument manufacturer.

5. Ultrasonic level gauge displays blind spots or exceeds the range
Common faults: The sensor makes noise, the display shows blind spots or exceeds the range.
Reason for malfunction: ① Exceeding the range of the ultrasonic level gauge;
② The measuring surface is too close to the probe;
③ Inappropriate use in high dust, high foam, high steam environment or working temperature too high or too low;
④ Improper setting of pulse intensity.
Troubleshooting: ① Adjust the actual range of the ultrasonic level gauge to within the working range of the instrument;
② Adjust the application environment to the required range;
③ Adjust the intensity of the emitted pulse until it stabilizes.  
6. The current output of the ultrasonic level gauge is abnormal
Common faults: Abnormal 4-20mA output; The current output is high, low, and jumping.
Fault cause: ① Excessive load resistance;
② The range 'range endpoint' has been modified, and the output fine-tuning parameters' output low-end fine-tuning 'or' output high-end fine-tuning 'have been modified;
③ Poor power rectification and filtering; ④ The power on time is not enough.
Fault handling: ① Reduce load resistance;
② Readjust relevant parameters by oneself;
③ Replace the DC stabilized power supply with a larger capacity; ④ Preheat after 15 minutes of power on.

7. Ultrasonic level gauge control output abnormal
Common malfunction: Control output does not operate.
Reason for malfunction: ① Incorrect parameter settings;
② The external current limiting resistor is too large;
③ The external current limiting resistor is too small and has damaged the ultrasonic level gauge.
Fault handling: ① Reset parameters;
② Reduce the current limiting resistor;
③ Contact the instrument manufacturer.
8. Ultrasonic level gauge RS-485 output abnormal
Common malfunction: The serial port cannot communicate.
Fault cause: ① Reverse connection of serial ports A and B;
② The serial port related parameter settings are inconsistent with the host.
Fault handling: ① Change wiring and reset parameters;
② It must be consistent with the upper computer.
9. The ultrasonic level gauge has a large error
Common faults: Sensor noise, level display value error of more than ten centimeters
Reason for malfunction: ① Not installed vertically, resulting in multiple reflections;
② The installation is too close to the tank wall, causing sound waves to reflect halfway;
③ Check if the setting of the difference "installation height" is correct;
④ Check if the temperature display value is normal.
Troubleshooting: ① Repeatedly adjust the installation position;
② Correctly set the "installation height" value;
③ If the temperature difference is large, adjust the "Temperature Modification" value to the correct value.