Up to fifty EAC-ACS-4Q modules can be arranged in parallel. Each PSU is able to operate independently, so that systems can be expanded or broken up as needs dictate. The modular approach is useful for test houses and research labs which regularly test different sized power devices. Individual units can be used for the day to day testing of multiple small devices, then grouped together for larger projects.

Individually Programmable Phases

All three of the EAC-ACS-4Q's individual phases are independently adjustable. This provides up to three power systems from one unit. Using the optional GridSim GUI, it is possible to program each phase for: voltage, frequency, phase angle, as well as superimposed harmonic and inter-harmonic voltages up to 5kHz. Different voltage waveforms per phase are also possible in amplifier mode.

Power Recycling

When functioning as a load, the EAC-ACS-4Q has an inbuilt monitoring system that synchronises with grid conditions. This recycles the AC/DC sink energy from the loadside back to the three phase mains.

Voltage Amplifier Mode

The EAC-ACS-4Q features a voltage amplifier mode as standard, allowing the unit to operate as a full 4-quadrant three phase amplifier. The module receives external signals via an analogue input for each phase. To achieve a desired output on the loadside of the module, the signals can be either amplified or reduced by a user defined scaling factor. Different waveforms are possible per phase.

Any device which creates -10 to +10V can be used as an external signal generator. This functionality is particularly useful for hardware in the loop (HIL) applications driven by a real time computer. Users also have the ability to discharge the EAC-ACS-4Q module through the amplifier mode.

Current Control Mode (Option /I-CONTROL)

For applications where you need to actively control the output current of the EAC-ACS-4Q, an additional current controlled amplifier mode is available. For example, a 10V input is equal to 124A for the 50kVA modules. So if you want an output of 62A, then a factor of 0.5 (62/124) is entered into the scaling field.

Each unit comes with an isolated analogue, Ethernet and USB interface as standard.

Standard ACScontrol GUI

All EAC-ACS-4Q units come with a simple and intuitive ACSControl operating GUI as standard. The module is connected to a PC via the standard Ethernet or USB interface. Live values of the power supply are displayed graphically along with any warning and error messages. Input values to the EAC-ACS-4Q from the local grid are also displayed, including: input current, reactive power, active power and Cosφ. The software allows protection levels to be set on both the lineside and loadside of the system.

As standard, ACSControl comes with a basic waveform generator mode. This allows users to implement sinewaves and edit parameters such as frequency and voltage (either L-N or L-L), as well as choosing the number of output phases (two or three). For more complex programming requirements, the optional GridSim GUI provides users with much greater functionality than standard ACSControl.

Constant Power MODE (Option /POWERMODE)

This option allows the modules to operate the in constant power mode. Apparent power and cos(phi), or active power and reactive power, can be set individually per phase or symmetrically across all phases. Test sequences are built out of multiple blocks within the software, with durations and rise times specified by the user to emulate the changing conditions of a complex load or grid.

Soft Tools

There is an API for .NET (Windows) along with LabVIEW drivers.

Full Waveform Generator Mode (Option /GRIDSIM)

Where more advanced testing is required, the optional GridSim GUI provides users with a selection of advanced features. The software allows for manual operation and programming, as well as automated test runs to be configured with ease. A set of predefined periodic waveforms are available including sine, clipped sine, square, triangle, sawtooth. User defined waveforms are also possible. 

A Fourier tool is provided that can create virtually any conceivable periodic waveform. Superimposed harmonic and inter-harmonic voltages are programmable up to 5000Hz. Individual waveforms, as well as the final synthesised waveform, are represented graphically within the software. As shown below, the synthesised waveform is shown in blue and the individual waveforms are shown in black.

Common grid conditions such as voltage dips, short interruptions and voltage spikes can be recreated. Non-periodic waveforms such as voltage ramps, DC straight lines (either positive or negative), step curves and exponential curves can also be programmed within GridSim. This allows virtually any conceivable waveform to be generated that is within the unit’s dynamic capabilities.

RLC Load Mode (Option /RLCLOAD)

The optional RLC load mode {Resistance (R), Inductance (L), Capacitance (C)} enables the user to set apparent (VA) and reactive power (VAR). It also allows the power factor (cos phi) to be adjusted. The simulated impedance is particularly useful for users who design, research and develop renewable systems which feed energy to the public grid.

The software allows the EAC-ACS-4Q to test against anti-islanding regulations for grid-tied power systems. As the EAC-ACS-4Q simulates impedance for these regulatory tests, users do not have to use real components. This drastically reduces set up time and minimises the possibility of human error within the setup of the test circuit. It also eliminates the need to buy lots of different high power components for multiple tests, which can often prove very expensive. 

Users can select between 12 different types of topology within the software. Each loadside phase can have its own RLC topology. Individual parameters of each topology circuit can be set to customise the test to your specific requirements.

Test Software (/EMC-XXX)

Specific EMC test standards listed in the datasheet are individually available to execute from the EAC-ACS-4Q's operating software. The GUI features a separate test interface for each standard and provides waveform visualisation, tracing, and verification capabilities. Automatic generation of test reports is also provided.

Each test consists of multiple sequences, which can be executed as a whole or as individually selected blocks. EMC classes 1 to 4 predefined by a specific standard are user selectable. There is also a class X available, where relevant variables are programmable. Example variables include dip deepness, harmonic content, and frequency shift.

Trigger signals are generated by the EAC-ACS-4Q for external measurements with a power analyser. To guarantee the conformity of the standard test, the voltage accuracy of the EAC-ACS-4Q can be verified by calibrated external measurement tools before executing the test procedure. If the accuracy is not within the limits according to the particular standard, calibration and adjustments can be implemented via the ACSControl GUI.

Voltage Slope Enhancer (/VSE)

The standards highlighted with asterisks in the datasheet require the execution of voltage drops, short interruptions, and voltage variations. Switching at any time is mandatory, not only at zero crossing of the voltage.

To achieve this an additional VSE (voltage slope enhancer) is available. The hardware allows for fast voltage slopes <5μs and current peaks up to 1000A, and for two different voltage sources to be switched between (e.g. AC grid and EAC-ACS-4Q), as shown in the diagram.

For additional safety, contactors are provided on both the lineside and the loadside of the EAC-ACS-4Q. These integrated safety relays provide a safe shutdown according to EN 13849-1 category 2/3. The ISR is connected to the external safety switch loop. If the external loop is opened, the EAC-ACS-4Q is powered down immediately.

Each unit has a liquid cooling circuit, which allows the 4 quadrant modules to be built into their compact 19" × 11U case. Should it not be feasible to connect the unit to an external cooling loop, then a separate module is optionally available to provide a liquid to air heat exchanger.

The rackmounting units can be treated to a laboratory rack or flight case integration. Having a programmable power system mounted into a flight case on castors is often advantageous, especially when several departments or test cells share the same equipment. 

Multiple power systems can be fitted into the same flight case. Door hangers are fitted for convenience. Existing ETPS systems can also be retrospectively integrated into new flight cases where requested.

The versatility of each unit allows for a wide variety of applications to be tested, including: single/three phase motor tests, AC transformer testing, grid-tied inverter analysis and aerospace electronics trials. The flexibility of the modules has allowed the University of Edinburgh to bring together experimental work in research areas such as power-electronics, electrical machines and smart grids in one lab. It has also enabled them to expand their research into new areas such as automotive and aerospace.

EMC Testing

Automated EMC tests can be programmed into the optional GridSim GUI. The power system is capable of testing against standards for voltage fluctuations, power frequency variations and short interruptions among others.

Each EAC-ACS-4Q has an incredibly high peak current capability. When combined with the voltage slope enhancer hardware, 50kVA modules are able to produce up to 1000A and simulate a voltage drop (phase loss) within 5µs.