WattNode Watt Transducers

Introduction

The Advanced Pulse-Output WattNode^® generates pulses in proportion to positive real energy consumed.  (Click here for a product spec sheet.) In addition, models are available with up to three pulse output streams, allowing measurements such as bidirectional energy and per-phase energy.  The per-phase measurement option can be used to measure up to three separate branch circuits with a single WattNode, saving money and space.  Other measurements with a pulse-output are possible, including reactive energy, apparent energy, voltage, etc.; the WattNode User Guide will help identify the model for your needs.

WattNode Features

The new WNB series products are ‘drop-in’ replacements for the original "WNA" series WattNodes.

Key New Features

1. Diagnostic LEDs on each phase show proper operation to facilitate installation.
2. Larger CT and Output terminal blocks and screws for easier wiring.
3. Pulse output options for bidirectional and single-phase measurements.

Diagnostic LEDs
Perhaps the most useful new feature is the multi-color LEDs that make troubleshooting connection problems, like swapped or reversed CTs, fast and easy to fix.  When you see three flashing green LEDs you know that each phase has voltage, kWh pulses are being generated, and every thing is working properly.

If any of the LEDs flash red, you may have a wiring error.  This powerful diagnostics feature can indicate problems such as high and low line voltage or frequency, unusual power factor, loose connections, and many other conditions.  See the WNB Series Installation and Operation Manual for complete details.

Easier Wiring
Another feature users will appreciate is the larger Current Transformer (CT) and Output terminal blocks.  The screws on these terminals fit a standard 1/8” screwdriver, just like the screws on the voltage terminals.  Another simplification is that the new wye and delta models both use the same size terminal blocks.  These changes make wiring easier then ever!

Pulse Output Options
In addition to these improvements, there are two major functional changes.  First, there are now two pulse outputs, P1 and P2, which makes the new WattNode a bidirectional transducer.  The P1 output generates kWh pulses just as the original WattNode did – when energy flows from the power line into a load, such as a motor.  Now if the load happens to be a building with solar panels and they start to make more energy then the building uses, the P2 output will generate pulses indicating that energy is now flowing in the opposite direction.  This bidirectional capability is especially useful in net metering and renewable energy applications.

Additional Features
The safety and accuracy of the new WNB delta models is significantly improved by using three CTs.  The original WNA delta models used only two CTs.  This saved the cost of one CTs but created a potential safety hazard because with this design one side of the CTs is connected to the high voltage power line.  In addition, this type of arrangement is not the best for accurate current measurements.

In addition to improved safety and accuracy, the new delta models provide an optional neutral connection, which means that delta models can now be used in three phase wye applications too.  User who do both wye and delta measurement can now buy just delta models.  Wye models are still required for single-phase measurements, such as 120-volt plug loads or 277 lighting circuits.

For accurate measurements, always connect the ground terminal on both wye and delta models to the electrical system’s green safety ground.  Wye models must also have their neutral terminal connected to the electrical system’s white neutral conductor.  The ground and neutral terminals connect to different points inside of the WattNode.  The ground connection provides a reference point for voltage measurements.  Wye model WattNodes are powered from the A Phase and Neutral connections and delta models are powered from the A Phase and B Phase connections.

For single-phase applications, wye models can be ordered with three separate pulse outputs, one for each phase.  The per-phase output option (-P3) offers a low-cost, space-saving way to measuring the energy used on each individual branch circuit. 

Other pulse-output models are available for special applications, including reactive energy, apparent energy, higher pulse resolution, voltage, etc.  Call 800-450-4454 or email us at sales@datalogger.com for additional information.

WattNode Models

WattNode models are available for use on single-phase, three-phase wye, and three-phase delta electrical systems with voltage ratings from 120 to 600 VAC. (We stock only the delta models of WattNode transducers as these work in most wye applications.) Current transformers are available from 5 amps to 1500 amps. Custom-made CTs are available in any opening size and amp rating by special order. There is a WattNode and CT combination available to measure virtually any electrical load.

The full scale measurement range of a WattNode depends on the model and current rating of the CTs. CTs are available in several styles, opening sizes, and ranges. For maximum measurement resolution use a CT with a full-scale current rating that matches or is slightly larger then the load current. Refer to the Current Transformers page for details.

Some Points To Remember:

• WattNodes use 3 CTs and all the CTs must be the same current rating.
  
  
• WattNodes also require a voltage connection (WNB-LEAD-SET) to function properly.
  
  
• A Pulse Input Adapter (S-UCC-M006) is needed to connect the WattNode to the Energy Logger Pro.
  
  
• All WattNode models have 3 CT inputs and are typically used to measure single and 3 phase motor loads at a location remote from an electrical panel where
  
  
• Wye models have 3 CT inputs and are used to measure single and 3 phase motor, lighting, whole building loads at a location, typically in an electrical panel, where there is a neutral wire. Wye models are not stocked as delta models will work in most wye applications.
  
  
• WattNodes and CTs have a 130% over range capability.

For assistance in selecting a WattNode model for your application please call 800-450-4454 or email us at sales@datalogger.com.