Archived: Using the Veris Industries H8040 Series Power Transducer with NI Wireless Sensor Networks

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Overview

Note: NI WSN products are not supported beyond LabVIEW 2015. If you have questions on migrating products, contact technical support at ni.com/support.



This document describes the use of the Veris Enercept H8040 series power transducers with the NI Wireless Sensor Networks (WSN) system for wireless power monitoring. This document is one in a series of documents describing how to use specific sensor products with the NI WSN system to enable a variety of applications, such as environmental monitoring, climate studies, and resource monitoring. For more information on using other sensors with the NI WSN system, please refer to the WSN Sensor Solutions document.

Contents

Veris Industries H8040 Series Power Transducers

The Veris Enercept H8040 series is used for industrial power monitoring.  The most common application is the monitoring of a building’s power consumption.

The Veris Enercept H8040 series monitors both the current and voltage passing through conductors.  The current is measured using one, two or three current transformers.  The voltage is sensed by separate leads.  Using Joule’s Law:  , the power is calculated by the internal microprocessor.  External power is provided to the transducer to output a standard linear output of 4-20mA proportional to power consumption.  It should be noted that the H8040 series is designed to be used with AC signals only.

Figure 1. Veris Enercept H8043 Sensor

There are four models in the Veris Enercept H8040 series.  Each model is used for different applications and can all be interfaced with National Instruments Wireless Sensor Nodes.  Namely, the Veris Enercept H8041, H8042, H8043, H8044.  Each sensor can either measure 1 or 3 phase signals at either 208V or 480V.

These sensors are designed for high voltage and current applications and it is therefore important to take the necessary precautions when installing these sensors.  Likely it will be necessary to have a licensed electrician install the sensor.  During installation ensure to follow the mounting instructions provided with the transducer.  Also ensure that all wires are mechanically secured near any connection points. 

Wireless Power Monitoring

Wireless power measurements now make it possible to monitor the power consumption of a given building complex without the need for extensive wiring systems.  In large building complexes there are multiple transformers that need to be monitored to accurately depict a building’s power consumption.  It is now easier than ever to install a power sensor on all of the transformers and wirelessly transmit this data back to a central computer where it can be scaled, analyzed and recorded. 

The major benefit of wireless data transfer with WSN is the ease of system expansion.  Adding monitoring points is as easy as adding a power transducer and wiring it up to a new or existing WSN node.  If it is a new node it is easily added to the system through the use of the I/O server.  If the node is too far to communicate with the gateway directly, other nodes in the system can be used to relay the data back to the gateway using WSN mesh networking. 

Connecting the Veris H8040 to NI WSN-3202 Node

The following hardware is needed to connect a Veris H8040 series sensor to an NI WSN node:

  1. WSN–3202 Voltage Node.
  2. External Power supply capable of 9-30VDC @ 30mA.
  3. Precision resistor to convert 4-20mA output to voltage, such as the SCXI Precision Resistor Kit (249Ω).  Note that this resistor value will map the 4-20mA signal to approximately 1-5 VDC.
  4. Shielded twisted pair wire Beldin 1120A or similar (length dependent on your application).

Figure 2 shows how connect the above components to properly read the current signal from the Veris sensor with NI’s WSN-3202. It is important to not ground the shield wire to the AI GND of the WSN Node. In this case if you are experiencing noise in your signal you should connect the shield of the Veris sensor to a suitable ground.  It should be noted that although the NI WSN-3202 Voltage node can provide excitation to certain sensors, the H8040 consumes too much power to be supplied directly  from the node.

Figure 2.  Connecting H8040 to WSN-3202

Wiring Diagram(s)

The Veris Series can be installed in a variety of configurations depending on the particular application that they are used for.  The Following images are taken from the installation manuals linked below and are application and sensor dependent.  Please ensure that you are using the correct wiring configuration for your application and sensor. 

Figure 3. Different Wiring Configurations for Veris Enercept H8040 Series Depending on Sensor and Application

Programming NI WSN for use with the H8040

Using LabVIEW on a host PC with the NI WSN-3202 with the H8040

Extracting the data from the NI WSN-3202 is fairly straightforward.  After creating a new project and adding the WSN gateway and nodes, as outlined in the Getting Started With WSN guide, it is necessary to configure the analog input channel to be used.  To do this, right click on the WSN -3202 Voltage Node and select Properties.  In the channels tab select the analog input channel that the sensor is connected to.  Select the appropriate channel range (+/-5V range if using 249Ω shunt resistor).  The sensor excitation option can be ignored as external excitation is used.  So long as the excitation leads on the node are not connected to a load no power will be drawn from the node. 

Once the node and gateway are setup it is a simple matter of acquiring the data, scaling it and displaying it.  NI WSN uses a share variable to bring the data into LabVIEW, which can be dragged and dropped onto the block diagram from the project explorer window.  Right click on the shared variable and select Show Time Stamp.  To ensure the indicator is updated with new data only, it is important that the data’s timestamp is not equal to the timestamp from the previous iteration.  To do this, compare the timestamp from the previous iteration to the current shared variable’s timestamp.  If the timestamps differ we update the indicator, if they are the same we do not update the indicator.  The scaling of the data is a simple linear relation that maps the 4-20 mA output to a 0 to maximum power.  Because the maximum power rating is unique to each sensor variation and it is possible to use different shunt resistors, front panel controls are used for these values.  

Figure 4. LabVIEW VI Block Diagram Running on Host Computer – Acquires, Scales and Displays Data.

Using LabVIEW WSN Embedded Programs on the NI WSN-3202 with the H8040

With LabVIEW WSN, it is possible to download and run LabVIEW VIs on the programmable version of the WSN-3202 node for local data processing and control.  For example, it is possible to scale the data to engineering units locally on the node.  It is possible to run more complex programs on the node to do certain control applications.  However because of the slow sampling rates needed for most power monitoring applications, this may not provide a meaningful advantage unless your specific application requires additional local processing or control.