WattsOn®: Universal Power Transducer


  • ANSI C12.20 Class 0.2 Accuracy compliant
  • Supports IEC 60687, IEC 61036, IEC 61268, IEC 62053-21, IEC 62053-22 & IEC 62053-23
  • Interfaces with CT including: 5A, mA, 333mV, Solid Core, Split Core, Rogowski Coil, etc.
  • Universal 24 VAC/VDC power supply
  • DIN Mount
  • High resolution (24-bit ADCs) with 16kHz sampling provide True RMS parameters per phase: Voltage, Current, Power, Energy (W, VA, VAR), frequency, power factor
  • Standard RS-485 (Modbus) communications
  • Integer and floating point data transfer
  • Compatible with 3-Phase/3-wire, 3-Phase/4-wire, split and single phase configurations
  • Four-quadrant energy and demand calculations
  • Per phase import/export energy accumulation
  • Two Pulse outputs, one for Wh, and the other configurable for VARh or direction of active power
  • Optional 0-10VDC analog outputs
  • Optional remote display (WattsOn-DISP)


  • Building Energy Management
  • Equipment Monitoring
  • Power Factor Correction
  • Individual Load monitoring (up to three single phase loads)
  • Renewable Energy Measurement
  • Import/Export Power/Energy Monitoring
  • Net Metering
  • Photovoltaic Solar Generation
  • Inverters
  • Wind Turbine Generation
  • OEM Applications (add value to equipment)

Product Description

The WattsOn universal power transducer utilizes cutting edge technology to implement a multi-functional power and energy transducer into a small, cost-effective package. WattsOn incorporates three meters into one to provide a unique solution for monitoring up to three single-phase loads, or one three-phase load. By using two of the inputs, it may be used with split-phase loads also.

WattsOn provides comprehensive per phase (as well as cumulative) information, including Volts, Amps, Real Power, Reactive Power, Apparent Power, Watt-hours, VAR-hours, VA-hours, Power Factor and Frequency.

Power (Real and Reactive) is a signed measurement and the meter accumulates both import and export energies as well as capacitive and reactive energy.

The unit accepts up to 600V (line-to-line) directly without the need for potential transformers. It accepts standard mV output CTs (333mV or 1000mV full scale output), as well as Elkor's line of "safe" mA split and solid core CTs. Optionally, the unit may be equipped with an internal interfacing module to accept any standard 5A CT.

The WattsOn transducer features a high accuracy chipset and provides register updates up to two times per second. The true-RMS inputs may be used even with distorted waveforms such as those generated by variable frequency drives and SCR loads.

Information is available via the RS-485 (Modbus RTU) output port. In addition, two solid-state relay pulse outputs are available for Wh energy pulses as well as Qh pulses or direction of power flow indication. Optionally, the second pulse output may be substituted for two 0-10VDC outputs that may represent any instantaneous parameter that the meter measures. The analog outputs and their scaling may be field selected and adjusted via the RS-485 output port.

An optional Display Module (WattsOn-DISP) is available for localized or remote viewing of measured parameters.


Line Parameters

Voltage: 600 V or 600/347 V
480 V or 480/277 V
208 V or 208/120 V

Single Phase, Split Phase, Three Phase
50 or 60 Hz
Current: (Version dependant)
"-mV": 333mV or 1000mV full scale output CTs.
"-mA": Elkor "Safe" mA output solid/split core CTs.
"-5A": 5A from industry standard CTs.


Wh/Qh: Solid state relay (24V, 150mA MAX), change of 100ms pulse on every pre-defined Wh value

Qh output software configurable to represent direction of real power flow.
Analog Outputs (-1200 version): Qh output may be substituted for two 0-10V analog outputs. Output parameters and span, and full scale may be field adjusted using Modbus communications.
RS-485 Port Modbus RTU; up to 64 units may be connected to one 'chain'.

Device Specifications

Power Supply: 15-24VAC or 20-30VDC, 100mA
Accuracy: ANSI Class 0.2 for power/energy (at 25°C, pf>=0.5)
See Accuracy table below for detailed accuracy specifications.
Environment: Protected Installation; -40 to +60°C, 10 to 90% RH non-condensing
Isolation: All line inputs are isolated from the outputs.
Hi-Pot testing: 2500VAC for one minute.
Enclosure: 3.7" x 3.8" x 1.7" (94 mm x 97 mm x 43 mm) W x L x H
(Note: Height does not include DIN base)

Accuracy Specifications

Parameter Accuracy (of reading) Basic Resolution
(must multiply by CT Ratio for actual resolution)
Voltage: 0.5% 0.1V
Current: 0.2% 0.001A
Power (W): 0.2% 0.1W (per phase, 1W per total)
Power (VA): 0.5% 0.1VA (per phase, 1VA per total)
Power (VAR): 0.5% 0.1VAR (per phase, 1VAR per total)
Power Factor: 0.5% 0.001
Frequency: 0.1% 0.1Hz
Energy: 0.2% 1Wh

Measured Parameters

(A, B, C, Avg, AB, AC, BC, Avg)
(A, B, C, Avg)
Apparent Power
(A, B, C, Total)
Reactive Power
(A, B, C, Total) - Bi-directional
Power Factor
(A, B, C, System) - Bi-directional

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Import/Export Energy
(A, B, C, Total)
Inductive/Capacitive Energy
(A, B, C, Total)
Apparent Energy
(A, B, C, Total)
Total Demand Power

Part Number Generator

Model Number
WattsOn 1100
RS-485, 2x pulse out

WattsOn 1200
RS-485, 1x pulse out, 2x analog out (0-10V)

Current Transformers


Model Number
WattsOn 1100
RS-485, 2x pulse out

WattsOn 1200
RS-485, 1x pulse out, 2x analog out (0-10V)

Current Transformers


Part Number


Modbus Commander LITE
Elkor WattsOn Console (deprecated)

Third Party Hardware Support


Elkor Technologies Inc.
Modbus/RTU-to-Modbus/TCP bridge
Hardware SCADA solution with web hosting, web push capability, trending and alarming.

Interface Hardware

FTDI USB-485 Converter USB-RS-485 Cables and Modules
USB-485 Converter Low cost USB-RS-485 Converter
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