As technology advances and network capabilities increase we’ve seen a great deal of change in the technology that utilities can use to monitor their electrical networks. Taking a closer look at the evolution of this market, the newest addition being offered provides the utility with data that when analysed enables the utility to be proactive rather than reactive to their ever changing requirements.

Traditionally with pole top distribution transformers, the only monitoring available was via an analogue maximum demand indicator (MDI). As standard the MDI was mounted up the pole close to the transformer and only had its reading taken when crew were available to visually take a reading and reset the unit. This single or three phase device only gives one maximum demand current indication that happened sometime between when it was last reset and the time the reading was taken.

Then came the electronic maximum demand indicator (eMDI). This device is solar powered with three phase current connections (via split core current transformers), recording data such as minimum, maximum and average current; transformer temperature; and ambient temperature. The eMDI utilises drive-by wireless data download, and can store up to two years worth of data at ten minute intervals. The eMDI has operated on the Australian electricity network since 2012.

The most recent development in distribution transformer monitoring comes from WF Energy Controls, in the form of the AM10. This device is an asset management tool designed specifically to monitor kiosk and pole top transformers, with a reference to voltage, current and temperature. The device can record and display voltage, current, voltage unbalance, power factor, frequency, sag/swell, harmonics to the 32nd harmonic, THD, phase angle and two temperatures.

Connection is via voltage transformers, or directly to the voltage; and to the current transformers, split core current transformer or Rogowski coils for current. The transformer temperature sensors are easy to install, using a magnet. The Rogowski option is preferred by many utilities for the ease of retrofitting where there are no in-situ current transformers available and space is tight.

The AM10 is also designed to measure multiple feeders per phase (up to five feeders/phase), which is important for high value kiosks in critical sites. The AM10 is a purpose built compact design that can fit most sites; and downloading the data recorded by the device (up to two years worth of data) is simple to do, via 3G cellular data or SD Card.

Offered with RPMS management software, the AM10 is a powerful tool to report on and manage all distribution and power transformers on a utility’s network. Informed decisions can be made about managing and right sizing of assets when annual load profiles can be properly recorded and analysed.

Key benefits of the WF Energy Controls distribution transformer monitors include:

  • The eMDI is a simple, solar powered device with easy drive by communications that provides considerably more data than traditional analogue MDIs.
  • The AM10 records large amounts of annual profile data for a range of sites, and with 3G communications, it is a powerful device that can quickly add a lot of value to the network.
  • Both devices are compact and purpose built with inbuilt communications, transformer and ambient temperature monitoring.
  • RPMS software is available to enhance the reporting of the data and more importantly to make better decisions about network assets.

WF Energy Controls is a privately-owned company specialising in the design and manufacture of current and voltage transformers for the low to medium voltage electrical industry. Based in Sydney, NSW, WF Energy Controls supply network and electric companies worldwide. For more information visit or phone 1300 665 374.

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