The Model LU77/78 Ultrasonic Level Switch uses a non contact liquid level sensor to measure up to 24.6 ft (7.5m) with integral three-channel relay control. The level switches can be used as a water level sensor and switch or for other liquids for reliable liquid level control. The liquid level switch has relays that can be configured for a single setpoint alarm or two latched setpoints for automatic fill or empty in simplex, duplex, or triplex control modes. Calibration for accurate liquid level measurement is quick and easy using a sequence of push-button entries. The ultrasonic level switches include local LCD indication to signal level values and relay status. The LU77/78 is designed with a NEMA 4X enclosure, suitable for outdoor applications. All LU77/78 switches are compatible with Building Automation Systems, BAS, and HVAC applications.