EMMA 3G Compliance
EMMA 3G Compliance and Development.
Compliance Test Results, May 2012
Compliance testing results for the production version of EMMA 3G. These tests were conducted in May 2012, on a random sample unit of EMMA before shipping. Additional technical documentation is available in the Installers section.
For more information about the results and how to interpret them, see our FAQ section on EMMA Compliance Testing. For an overview of how EMMA's pulse width modulation works (PWM), read How EMMA 3G PWM control works.
The plots from the Conducted Emissions Tests are shown at 25%, 50% and 75%. They show that the conducted emissions from EMMA are well below the relevant limits.
The Temperature Test Results are from a unit left running at 50% power connected to a 3kW heater until the temperature of the filters reached steady state. This shows that the filters stabilised at circa 47 degrees C. The filters are rated for ambient conditions of 100 degrees C and don't saturate until they reach circa 120 degrees C. EMMAs filters are thus operating well within their specified limits.
Harmonics Test Results are shown at 25%, 50% and 75%. The results show that EMMA is almost completely harmonics free and well within all the required limits: EMMA creates little or no harmonics on the DNO's network. The results show that EMMA does not impact the DNO's network with harmonics, when compared with the existing harmonics on the network without EMMA. The test results are from zero to one hundred percent in increments.
Results also show how efficient EMMA is. It draws only circa 2.9 watts in the idle state.
Development of EMMA 3G for compliance
The EMMA 3G was developed over 4 years ago to provide High Speed Pulse Width Modulation of power to resistive heating loads in a compliant manner.
The EMMA 3G has been independently tested by Compliance Engineering Ireland (CEI) in accordance with the standards we have agreed are correct with the UK DNO's such as SPEN and SSEPD. It has also been independently successfully tested by Imperial College for Scottish and Southern Energy Power Distribution as well as being independently tested on trial sites for small and larger scale export control by Scottish Power.
The EMMA 3G unit uses High Speed Pulse Width Modulation technology to produce a Pure Sine Wave output that varies in amplitude based on a control signal.
EMMA with Export Control DNO compliance testing
The EMMA 3G with export control is our older generation unit which has been developed in collaboration with several large UK DNO's over during last five years. The initial concept was put together in October 2010 at the request of Mr Bill Halliwell of Electricity Northwest (then United Utilities). The aim was to provide a means of manging on-site load in a way that ensures that export from sites with grid-connected generators is limited to that permitted by the DNO... with absolute certainty.
This is achieved primarily by adjusting the amount of power sent to suitably sized resistive loads on site in a way that ensures that the difference between generator output and site load is always precisely the same as or less than, the permitted export limit. The resistive loads are typically comprised of a battery of 3kW immersion heaters in a buffer tank (or in-line heater) serving on-site loads including hot water, heating, dairy wash down, dairy sterilisatiion, drying (timber, grain, chicken droppings) and swimming pools.
The first challenge was to develop a control system that does this in a harmonics "free", seamlessly smooth (i.e. flicker free) way that ensures there are no associated power quality issues. We have worked very closely with Scottish Power Energy Networks (SPEN) and Scottish and Southern Energy Power Distribution (SSEPD) on this aspect of the design during the last two years... both in the field where many trial installations with generators ranging in size from c.10kW now going up to c.250kW (both PV and Wind Turbines) and export limits ranging from 0kW to 50kW were intensely monitored; and in the laboratory at Imperial College London where a number of EMMA units have been intensively tested on behalf of SSEPD.
The second challenge was to make these devices "fail safe". This is achieved in two ways. The units themselves maintain a running real-time measurement of power exchange with the grid i.e. import or export. This figure is compared with the permitted export limit every c.10 milliseconds and is used to generate a running 30 second average. In the event of this average exceeding the permitted limit by an agreed margin (typically 5 Amps per phase) for more than a permitted period (30 seconds) [this is required to cope with instantaneous variations when large site loads are switched off] the system isolates the generator by tripping the G59 isolator for an agreed minimum period. There are further protections built into the system such as powered on isolator control (i.e. the generator is isolated in the event of an internal PSU failing) and delayed start up (which ensures that the generator isn't connected before the 30 second running average is established).
The second "fail safe" protection consists of additional reverse flow G59 detection and isolation... which is normally used on sites with large RE generators i.e. above 100kW.
Our compliance certs can be downloaded under the documents tab of this section.