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The Wireless Transducer Receiver (WTR420) shall read the liquid level information in the radio signal from the nearby Wireless Transducer Transmitter and provide an analog 4-20mA output and SCADA register data representing the liquid level being monitored. The Receiver shall obtain the liquid level by radio signal from the Pressure Sensor, which shall be submerged near the bottom of the tank, and connected by cable to the Wireless Transducer Transmitter.
Unit of Measure


Maximum Input Power

N/A 24 VDC ± 10%, 120 mA

Non-Isolated Analog Output Current

N/A 4 to 20 mA

Analog Output Maximum Load

N/A 600 ohm

Radio Communication

N/A ZigBee / IEEE 802.15.4

Operating Frequency of Radio Communication

N/A 2.4 GHz

Operating Temperature

N/A - 20 to 65 ºC

Storage Temperature

N/A -45 to +85 ºC

Enclosure Material

N/A Aluminum, Din Rail Mounted

Fitting Size

N/A 1/2 in NPT

Minimum Working Pressure

N/A 5.5 lb

Transducer Pressure Sensor

N/A When submersed in liquid, the Pressure Sensor shall convert the pressure exerted by the liquid into an analog voltage signal that shall represent the liquid level. The pressure sensor shall measure the absolute pressure, and the receiver shall contain a sensor to measure atmospheric pressure to make corrections for changes in the barometric pressure. These corrections to the barometric pressure shall be performed in the Receiver where the local atmospheric pressure is measured and subtracted from the absolute pressure signal.

A stainless steel diaphragm and silicone oil fill is provided to isolate and protect the pressure sensor from the liquid being measured. The weight of the Pressure Sensor acts to reduce its movement when placed in a moving liquid, and shall be a minimum of 5.5 lbs. A Strength Cord shall be part of the cable construction, proving the cable ample support for its weight. In applications where strong currents may be present, there shall be a 1/2" NPT fitting on top may be used to mount the transducer body in a fixed position. The Pressure Sensor and the Transmitter shall be connected together, tested and calibrated as a single unit. There shall be a number of pressures ranges and cable lengths available.

Additional Description

N/A The WTR420 shall provide four levels of Radio Link Quality indication. The four levels shall be defined as HIGH, GOOD, LOW, and LOST. HIGH, shall indicate strong error free communication. GOOD, shall indicate good but less than ideal communication. LOW, shall indicate intermittent and unreliable communication. LOST, which shall indicate no communication with the Transmitter.

The WTR420 shall provide a BATTERY LOW indication to indicate the condition of the battery in the Transmitter. The indicator shall blink when the battery has low voltage and must be replaced.

The WTR420 shall contain Zero and Span potentiometers are for field calibration.

The WTR420 acts as a Modbus RTU slave. Connecting the RS-232 serial port (or optional Ethernet Port) to a SCADA system shall allow the liquid level to be monitored remotely.

Additional setup and troubleshooting features shall be available using the separately supplied Touch Screen Interface Device (TSID), manufactured by M.P. Electronics.

The Transmitter and Receiver shall be capable of reliable communication even with the Transmitter under the concrete slab of a lift station wet well. The Antenna for the Receiver shall be mounted external to the control panel that the Receiver is installed in. For applications where the Transmitter and Receiver Antenna have line of site, reliable communication shall be maintained at distances up to 125 feet.

The Wireless Transmitter shall be part number WTT-A-B, where A is the pressure range, and B is the cable length, The Wireless Receiver shall be part number WTR420-X, where X is blank for the standard unit with an RS232 Serial Port, or X equals E for the optional Ethernet connectivity.