Quantitative Support

We have done many instrument development projects and -despite this- still occasionally find ourselves confused about the gritty details it takes to get things right, e.g. is that current phasor actually leading or is there mismatched group delay in the digital filters somewhere and the voltage signal is actually late? Sometimes non-linear analog effects drive you nuts. A common case is where the phase response of magnetics is a function of the amplitude of the current flowing through them. Applying delay corrections is also deserving of special attention – are you correcting for group delay or phase delay? (Forgot the difference, uh oh … not good.)

The tighter the spec of the instrument, the tougher the whole problem becomes. If you’re doing an instrument that requires a third party certification we unfortunately can’t do that. But since the folks that do charge a lot more than us, it’s probably worth your while to let us give your prototype the once over before it heads for one of those really expensive (and strictly hands off) test labs.

The accuracy limits of our instrumentation at power frequencies are roughly 0.05% in amplitude and 0.1 degree in phase for voltages up to 14.4KV and currents up to about 500A. We routinely do harmonic work to order 50 and can go up to order 100 if necessary. We also have an environmental chamber covering the range of -70C to +100C.

We are great proponents of coaxial excitation methods for testing but these do need to be used with great care. The big advantage is that these methods can create an environment where an instrument “sees” 100A at 10KV without a huge load bank dissipating 1MW sitting in our driveway (although we have done full power tests for our clients).

Sometimes what you need is somebody to measure the analog magnitude/phase response of a transducer and get the data back quickly. We have a superb instrument that can do that. Sometimes you see an effect that just makes no sense (this happens a lot in compact 3-phase watthour meters). We have already figured a number of these out and might be able to save you time.

We’re pretty creative about running experiments and have done all sorts of quick tests to help our clients keep their development projects on track. The most fun we’ve had in a while was making movies of explosive disconnectors doing their job for a client in August 2014. Wow, those things are loud!

We are thoroughly familiar with utility operations on US and European grids but have particular expertise with the Australian grid that came from earlier development efforts with several Australian utilities. One element of that work dealt with expanding the dynamic range of a zero sequence current determination on a delta-connected overhead MV distribution network. The essence of the problem turned out to be magnetic crosstalk into the transducer and the movie is an example of how we were able to collaborate with our customer across 10,000+ miles and 15 time zones.

While we love to do end-to-end custom development jobs, we’re also happy to collaborate with others in the industry and can do so silently if that’s an issue. Just open the conversation with an email to “info@DJAEngineering.com” and let’s get busy. Chances are both of us will learn something along the way.

Areas of Expertise

DJA provides a broad range of engineering services from technical consulting to full design/testing of AC power measurement systems operating at voltages from 120V to 35KV. We help get your power metrology job done cost-effectively with a wealth of knowledge in the following areas:
We are experts using modern digital sampling techniques with both time and frequency domain data analysis methods for the full range of home/commercial/professional applications. [learn more]
Current/voltage transducers are a necessary evil and we understand how to identify the best ones for every job. We also have particular expertise in Rogowski coil current sensors. [learn more]
Extracting what one needs to understand from standards is rarely easy and some important ones are downright daunting. We have a broad understanding of the applicable standards and can help navigate the best path through the maze. [learn more]
Safety must be designed into every power metrology product and assurance is a big deal, especially for high voltage electric utility equipment. We are also experts at making best use of expensive external labs. [learn more]
Neutral, third party evaluation of the methods used and data being delivered by newer SmartGrid instruments can streamline procurements, expedite trials and maybe even avoid legal bills. [learn more]
We have deep experience with both narrow and broad band PLC technology can make it work for you when that makes sense or make sure you avoid it when it doesn’t. [learn more]
We have a collection of reference instruments and intimate knowledge of the tricks of the trade. We can work with you in depth or provide just the specific answers you need for your project. [learn more]