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Product Discontinued
Information is for legacy purposes
kWh Transducer/Submeter
True RMS

This product line is no longer being sold, information is for legacy purposes.

The WNA Pulse Output WattNode has been replaced with the Advanced Pulse WattNode

Instructions (PDF) on migrating to the new models.

The Pulse Output WattNode® is a true RMS AC watt-hour transducer with pulse output (solid state relay closure) proportional to kWh consumed. The WattNode provides accurate measurement at low cost to meet your needs for sub-metering, energy management, and performance contracting applications.

Easy installation saves you time and money. The WattNode is small enough to fit entirely within a standard electrical panel and the screw terminals unplug for easy wiring.

The complete Pulse Output family measures 1, 2, or 3 phases in 2, 3, or 4 wire configurations. With voltage ratings from 120 to 600 VAC and current transformer (CT) ratings from 5 to 3000 amps, there is a WattNode combination to meet your AC power measurement requirements.

Accuracy of the WattNode is 0.5% of reading over a wide range of power factor and harmonic content. The WattNode measures true RMS power even with leading or lagging power factor and chopped or distorted waveforms. This makes the WattNode ideas for monitoring motors and pumps controlled by variable speed drives.

To assure reliability and accuracy, each WattNode is tested and calibrated by a custom, automated production system. A key part of the production system is a NIST traceable, precision voltage source that establishes the high accuracy associated with the WattNode. To assure the initial calibration accuracy is maintained, the WattNode has been designed with fixed, precision resistors, not potentiometers, in its measurement circuit.

Our safe CTs, with integral burden resistors, produce a voltage proportional to the load current. At rated current the voltage is only 0.333 VAC. Split core CTs quickly install on existing wiring and solid core CTs can prevent tampering. Bus bar CTs are available in a variety of standard sizes, plus custom designs up to 10″ x 10″ (254mm x 254mm) and 4000A.

The optional LCD module remotely displays energy in WH, kWh, or MWH; or power in W or kW. To protect the kWh total you can disable the front panel reset button and use a wired remote reset. The eight digit panel mount display runs for four years on a single replaceable battery.

  • Pulse output – Compatible with energy management systems and data loggers.
  • Small size – Can be installed in existing service panels or junction boxes.
  • Uses safe CTs – Integral burden resistor limits the output to low voltage.
  • Line powered – No external supply required.
  • Detachable terminal blocks – Easy to install and remove.
  • UL Listed – Designed and tested for safety.


Measurement Configurations

  • Single phase: 2 or 3 wire
  • Three phase: 4 wire
  • Three phase: 3 wire


  • Line powered
  • FCC Class A
  • Operating Voltage Range: ±20% of nominal
  • Power Line Frequency: 50 or 60 Hz
  • CT Input: 0 – 0.5 VAC operating, 3 VAC maximum

Pulse Output

  • Square-Wave output: 50% duty cycle
  • Optoisolator (phototransistor) output handles up to 50 mA at 3-35 VDC
  • Fully isolated to withstand 2500 volts

Frequencies at Full Scale Power

WattNode Model Frequency
WNA-1P-240-P 2.667 Hz
WNA-3Y-xxx-P 4.000 Hz
WNA-3D-xxx-P 2.667 Hz

Higher output frequencies are available. Call for more information.

TTL Output Option

  • 0 – 5 volt TTL square-wave output – short circuit protected
  • Fully isolated to withstand 1500 volts
  • Specify with ‘-TTL’ at end of model number


  • 0.45% of reading + 0.05% of full scale through 25th harmonic


  • Operating Temperature: -30° to 60°C
  • Humidity: Up to 90% RH (non-condensing)

WattNode Dimensions


  • Enclosure: High impact, UL rated, ABS plastic
  • Size: 143mm x 85mm x 32mm (5.63″ x 3.34″ x 1.25″)
  • Connectors: Euroblock style detachable screw terminals
    • Green: 12 – 22 AWG, 600 V
    • Black: 16 – 26 AWG, 300 V

Optional LCD Display

  • LCD Display Display: Eight digits, each 0.43″ high
  • Units: Power in W or kW, Energy in WH, kWh or MWH
  • Reset: Remote wire and configurable front panel button
  • Enclosure: Panel mount box, 75mm x 40mm x 38.5mm (2.95″ x 1.57″ x 1.52″)
  • Battery: Lithium 2/3 A, replace every four years
  • Backlit versions available
  • See our LCD Display Page.


Model VAC Phase
to Neutral
VAC Phase
to Phase
Phases Wires
WNA-1P-240-P 120 240 1 2 or 3
WNA-3Y-208-P 120 208-240 3 4
WNA-3Y-400-P 230 400 3 4
WNA-3Y-480-P 277 480 3 4
WNA-3Y-600-P 347 600 3 4
WNA-3D-240-P N/A 208-240 3 3
WNA-3D-480-P N/A 480 3 3

The delta models, WNA-3D-xxx-P, are used only when neutral is not present.

Datasheet, Manuals and Application Notes