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WattsOn® - Universal Power Transducer

The WattsOn universal digital power transducer uses cutting-edge metering technology to provide unprecedented accuracy and metering information for any electrical installation. WattsOn monitors each phase individually and incorporates the functions of single-phase, split-phase, and three-phase meters, to provide over 15 electrical measurements, per phase.


  • 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 almost ANY CT including: 
    5A, mA, 333mV, 500mV, 1000mV, 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 Remote Display Module (WattsOn-RDM) is available for localized or remote viewing of measured parameters.




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


(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.



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'. 


Power Supply:

15-24VAC or 20-30VDC, 100mA


ANSI Class 0.2 for power/energy
(at 25°C, pf>=0.5)
See Accuracy table below for detailed accuracy specifications.
Environment: Indoor; 0 to 60C, 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" (94mm x 97 mm x 43 mm) W x L x H (note: height does not include DIN base)
Safety: UL 508 Recognized (Canada and US)


Parameter Accuracy
(of reading)
Basic Resolution
(must multiply by "CT Ratio" for actual resolution)


0.5% 0.1V


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


  • Voltage (A, B, C, Avg, AB, AC, BC, Avg)

  • Current (A, B, C, Avg)

  • Active Power (A, B, C, Total) - Bi-directional

  • Apparent Power (A, B, C, Total)

  • Reactive Power (A, B, C, Total) - Bi-directional

  • Power Factor (A, B, C, System) - Bi-directional

  • Frequency

  • Import/Export Energy (A, B, C, Total)

  • Inductive/Capacitive Energy(A, B, C, Total)

  • Apparent Energy (A, B, C, Total)

  • Total Demand Power (W)

Ordering Information:


    [1] Specifies Output Type: 
= RS-485 + 2 x Pulse;     
= RS-485 + 1 x Pulse + 2 x Analog

    [2] Specifies CT Input Type (for example): 

Industry Stardard 5A CTs:


Inputs for 5A CTs
Solid Core 5A CTs: SCT Series
Split Core 5A CTs: (contact Elkor for details)


Solid Core CTs:


Inputs for MCTA CTs (full scale current must follow, up to 300A)


Inputs for MCTB CTs (full scale current must follow, up to 450A)


Split Core CTs:


Inputs for MSCT1 CTs (full scale current must follow, up to 200A)


Inputs for MSCT2 CTs (full scale current must follow, up to 600A)


Inputs for MSCT3 CTs (full scale current must follow, up to 1000A)



Inputs for MSCT5 CTs (full scale current must follow, up to 2000A)


Inputs for MS160 CTs (full scale current must follow, up to 100A)


Inputs for MS240 CTs (full scale current must follow, up to 400A)


Inputs for MS360 CTs (full scale current must follow, up to 600A)


Voltage Output CTs:


Inputs for 333mV CTs

*** Contact Elkor for other input options

    [3] Specifies CT full scale current (Not required for 5A or 333mV options)

    [4] Specifies Nominal Frequency (for greater accuracy). (60Hz is assumed if not specified)

*** Note: By default, analog outputs are configured as 1) Total Real Power and 2) Average Current. The anticipated nominal voltage should be stated to properly configure the output scaling. Analog output values and scaling may be changed later via Modbus.

Example: WattsOn-1200-MSCT3-800A-50Hz

Specifies transducer with 0-10V analog outputs, and current inputs calibrated for MSCT3 CTs, 800A maximum full scale, with a nominal frequency of 50Hz

Example: WattsOn-1100-5A

Specifies transducer with two pulse outputs, calibrated for 5A inputs, and 60Hz nominal frequency.


Part Number Generator:




Application Notes




Elkor WattsOn Console Software
EXE Setup

ZIPed EXE Setup

WattsOn Web Server Software
v0.9 Beta
EXE Setup

Installation Considerations
AN0303 - Modbus RTU Troubleshooting
AN0305 - Introduction to Current Transformers
AN0306 - WattsOn Split-Phase + Inverter Mode
AN0801 - WattsOn-DISP Wiring and Configuration
AN0802 - WattsOn Troubleshooting
AN0803 - Using CTs With WattsOn
AN0805 - Using WattsOn in Single Phase Applications
AN0806 - Power Monitoring Guide
AN0807 - USB-to-RS-485 Wiring and Installation

Third Party WattsOn Support

(known working with WattsOn)

Elkor Technologies Inc.
Modbus/RTU-to-Modbus/TCP bridge
iLon Smart Server
Hardware SCADA solution with web hosting as well as logic control.

XML Template for iLon Smart Server:
(right-click, Save As to prevent from opening in browser)

Hardware SCADA solution with web hosting, web push capability, trending and alarming.
SiteBoss S550
SiteBoss S570
Remote Site Manager for Cabinet, Remote Access, and Server Equipment Room applications.
Interface Hardware  
USB-485 Converter Low cost USB-RS-485 Converter
Serial-485 Converter Line of RS-232 to RS-485 converters (Elkor recommends the 485SD9TB)


copyright (c) Elkor Technologies Inc.

power meter


power transducer