Last week, we covered a few trip points (six, to be exact) programmed into the IRU ultrasonic sensor series. Using either of the two with hysteresis is a good way to combat chatter – a phenomenon that happens when a single switch point flutters between open and close.
Chatter is usually due to relatively slight turbulence in a tank, when the level sits just above or below the switch point. It wreaks havoc on pumps because it turns the pump on and off in rapid succession, adding extreme wear and tear.
A way to solve this problem is by programming an IRU series ultrasonic sensor trip point with the “Trip Distance”, “Trip Window” features and by setting the proper “Trip Type” which will add hysteresis (see “6 Handy Trip Points on the IRU Ultrasonic Sensor”). We’re going to show you how to do this.
Using the following tank level application parameters, here are the steps to program the IRU sensor to use hysteresis and eliminate pump chatter:
- Application: Tank Fill Control
- Tank Height: 10 ft.
- Sensor Blanking Distance: 2 ft.
- Full level: 2 ft. from sensor face (10 ft. level from bottom of tank)
- Empty Level: 11 ft. from sensor face (1 ft. from bottom)
- Step 1: Connect the RST-3001 module to the sensor and your computer.
- Step 2: Open the IRU software. Confirm that sensor communication has been established and parameter windows are showing the sensor’s settings.
- Step 3: Enter 2 ft in the “Trip Distance 1” parameter window. This is how far away from the transducer face the level will be when full.
- Step 4: Enter 9 ft. in the “Trip Window 1” parameter window. This is the distance between the full trip point and the empty trip point.
- Step 5: Enter “5” in the “Trip Type 1” parameter window. Trip Type 5 is called “Hysteresis Far”, which provides the fill control with hysteresis programming.
- Step 6: Click on the “Send” tab. This will send the new parameters to the sensor.
When the tank reaches the low level, the relay output activates and the pump will start filling the tank with liquid. When the liquid reaches the full level (2 ft. from sensor face), the relay output will deactivate and turn the pump off.
The pump will stay off until the liquid falls back to the low level point where the process will repeat. This delay of the pump – staying off until the liquid level falls to the low level – is hysteresis. Pump chatter is eliminated and the pump’s life is extended.