Up to 64 LAB-GSS modules can be arranged in series, parallel or matrix array configurations. Each module is able to operate independently, so that systems can be reconfigured, expanded or broken up as needs dictate. Inbuilt system comms allow users to switch between various set-ups.

The modular approach is useful for test houses and research labs who regularly test different sized power devices. Individual modules can be used for the day to day testing of multiple small devices, then grouped together for larger projects.

Power Recycling

When sinking energy from the unit under test the LAB-GSS automatically inverts the DC to AC and synchronises this output to the grid. The energy recycled to the grid only has typical losses of around 7%. 

This differs from conventional electronic loads which traditionally waste 100% of electrical energy that could be reused, by simply dissipating it as heat. By using this approach users can save significant electricity costs. Energy waste and thermal issues associated with traditional heat dissipative loads are also eliminated.

Internal Resistance Range

Each module is built with a user programmable internal resistance range as standard. This makes the power supplies ideal for simulating the output of energy storage devices such as battery packs, fuel cell stacks and super capacitors. The exact range varies by module and can be viewed in the selection table. An extended programming range is available (option /IRXTS).

Sense Compensation

Sense plus terminals are built into the LAB-GSS for the connection of sense wire which compensates for voltage drops in the load lines. This has a number of advantages over traditional sense. It is permitted to interrupt the load line during operation (voltage on). The maximum voltage drop compensation is adjustable. 

The voltage difference between LAB-GSS output and sensing point is monitored. If a set limit is exceeded, the LAB-GSS unit shuts off. This is particularly useful for applications with long cables often prone to unwanted voltage drops.

Versatile Limit Setting (VLS)

The VLS allows the LAB-GSS's output relays to be activated automatically when specific output values are met, protecting the DUT from any damaging charge conditions. Output voltage, current and power values which exceed or fall below a given limit or operating window can be programmed to trigger the relays. Active and inactive areas of operation are defined by a limit value, hysteresis value or a directional designator for the hysteresis.

Every module features constant current, constant voltage, constant power as standard. Adjustable internal resistance is also provided.

Active Power Factor Correction

LAB-GSS modules have Active Power Factor Correction (PFC) circuit integrated into the input stage as standard. This enhances the overall efficiency of the modules across the output power range when compared to a unit that does not have active PFC. In practice, this means a significant lower peak current value, a decrease of RMS value of the phase current and less perturbations of other equipment running on the same grid.

The inbuilt active PFC is also ideal for operating the power supply from a generator. Generators tend to be sensitive against high current peaks, and their voltage controllers may have some stability problems with non-sinusoidal load currents. The active PFC feature forms a lowpass filter and therefore, both the repetitive current peaks and also the harmonic content is enhanced. This will help the generator system maintain a stable and reliable output.

DC Input

Where users only have access to a DC link, special CON-DSS bidirectional units have been produced with a DC input. The full functionality of the power supply is still provided.

A variety of control methods are available. As standard each module is built with isolated analogue and RS-232 interfaces. Front panel control and display along with IEEE 488.2 (GPIB), USB, RS-422 and Ethernet interfaces are optionally available.

RS-232 Interface

The RS-232 interface is configured as a Sub-D 9 pin connector (female) and is located on the front panel. This interface can be optionally moved to the rear panel. The graphical user interface, TopControl is operated via RS-232. The software runs on Windows and allows the user to control, measure and configure the power system.

Analogue Interface

The control port is configured as a Sub-D 25 female connector and is located on the rear panel. It allows output values to be set and read proportionally using a 0-10VDC analogue signal. Digital inputs and outputs enable various functions such as the interlock and output ON/OFF. A 10VDC reference is provided for analogue control. Digital functions are switched via a high/low signal. A 24VDC supply voltage is provided for these functions.

CANmp Interface (Option /CANMP)

CANmp is a high speed digital interface operating at 1kHz. The interface gives users the capability to customise the CAN protocol. Up to 50 messages are user configurable. Along with the CAN ID the data length code, byte order, start bit, data type and signal factor can be adjusted by the user. A DBC file is provided and messages can be easily configured within the standard windows software. Messages can be sent cyclically or upon receipt of a sync or syncID signal.

Standard TopControl GUI

All LAB-GSS units come with a simple and intuitive TopControl operating GUI as standard. Live values of the power system are displayed graphically along with any warning and error messages. The software provides a variety of second level parameters, ideal for users who like to optimise their test processes. In standard user mode the operator can remotely program set values, enable voltage output as well as the ability to analyse different variables including set and actual values via the integrated scope.

The scope function can simultaneously record up to 8 system variables. Recording can be started manually or by a defined trigger event from any variable of the system. All actual and set values (currents/voltages/power/internal resistance) can be recorded. Other recordable items include system temperatures, intermediate DC circuit, low voltage auxiliary power supplies, error related values and variables from the controller section. 

A password protected section is available to the advanced user and service technician. In addition to the standard functions the authorised user is able to:

• Program linear ramp functions at start up and set value steps during operation
• Configure multi-unit operation
• Program the PID controller parameters
• Program the unit's limit values
• Calibrate and adjust values as necessary
• Update the firmware

Function Generator (Option /TFE)

Complex DC waveforms can be implemented through an optional embedded function generator. The highly programmable nature of the function generator allows users to plot out exact waveforms. This is often advantageous when emulating a power device with a very specific behaviour profile. For example, when quality testing fuel cell powered equipment, the specific behaviour of a discharging fuel cell can be programmed and replicated.

As well as custom shapes, standard square, sawtooth and sine waveforms can be plotted against time. Voltage/current and voltage/power relationships can also be programmed where necessary. Parametric programming is possible, where instead of the time axis, an input variable V_IN, I_IN or P_IN can be selected.

Soft Tools

An API for dotNET/C# programming is provided to simplify the integration into 3rd party control and measurements software platforms such as LabVIEW and Matlab. The API can be used to integrate into Python or remote systems based on the REST architecture.

Battery Emulation (Option /BATSIM)

BatSim provides a convenient method for the LAB-GSS to emulate different sized battery stacks. Nearly all relevant electrical characteristics are programmable, including the number of cells, energy capacity, cut off limits, chemistry type and nominal voltage.

Electric/Battery Drive Cycling (Option /BATCONTROL)

Drive cycle tests can be implemented using BatControl. Previous data obtained from a test track can be imported and recreated, allowing the LAB-GSS to simulate a real world driving test inside a lab environment. Battery and capacitor charge/discharge profiles can also be implemented through the GUI.

Capacitor Simulation (Option /CAPSIM)

The bidirectional characteristics of a real capacitor stack can be emulated when CapSim is installed with LAB-GSS modules. Number of cells in series/parallel, state of charge, cell cut off limits, dynamic capacitance and resistance are programmable.

Solar Array Simulation (Option /SAS)

SASControl software has all EN 50530 tests pre-installed. The GUI allows users to edit irradiance, temperature and amplitude values. Previous tests have been conducted using over 400,000 individual data points, with more possible.

Integrated Safety Relay (Option /ISR)

For additional safety, a mechanical interlock is available for the mains input of the LAB-GSS. The integrated safety relay provides shutdown safety 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 DC-output of the power system is powered down immediately.

Protection Against Output Bars (Option /PACOB)

A specially produced cover is available which provides protection against accidental contact of AC and DC current bars.

Automatic Voltage Matching with RPP (Option /RPP)

When researching energy storage devices, Reverse Polarity Protection (RPP) is recommended for devices without an automatic voltage matching circuit. With the LAB-GSS energised but output off, the RPP senses the voltage of the connected energy storage device. A contactor is closed after matching the voltage, to prevent large inrush currents and arcing on start up.

Ruggedisation Specification (Option /4111)

Ruggedisation of units to military standards is possible. Many previous modifications have been carried out for shipborne and vehicle projects. Our design team can work with you to meet specific requirements and standards. This ensures suitability in harsh conditions by providing protection against shock, vibration and humidity.

One previous modification included modifying a LAB-GSS system to withstand up to 30g of mechanical shock across X, Y and Z axes. The PSU also could operate from temperatures as low as -10°C all the way up to 55°C. For more information about what ruggedisations have previously been achieved, please contact ETPS.

Remote Control Unit (Option /RCU)

The RCU is an external control unit for controlling multi-module systems, which reduces response times when implementing complex changes. The RCU is available as either a desktop unit or a 19" rackmounting module, with or without an emergency stop.

Liquid Cooling (Option /LCAL)

Liquid cooling of the LAB-GSS's power stage is available for units which may be subject to naturally hot or uncontrolled environments. This enables operation up to 45°C with no performance derating.

The standard 19" LAB-GSS rackmounting modules can be treated to a laboratory rack or flight case integration. Common options include mains cables, passive indication of any residual DC voltage, isolation monitoring of DC cables and a panel mounted emergency stop. Switch panels with removable DC links can be fitted for modular systems. This simplifies the reconfiguration between series, parallel or independent use. Simple wheeled cabinets are also available. 

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.

If your test requirement is short term, we have a 32kW/65V LAB-GSS module in our rental range. We also have other bidirectional DC systems up to 216kW/2000V/2704A.

The versatile programming capability of the LAB-GSS ensures that it is popular across many research and development sectors. Common applications include battery/capacitor emulation, implementing drive cycles, fuel cell loading, testing flywheels, battery cycling, component lifetime testing, as well as the testing of inverters and DC-DC converters.

The systems are particularly popular in mild hybrid and electric vehicle research, with the UK's largest independent automotive EV powertrain testing facility Intertek Transportation Technologies using them within their test cells. A system has also been utilised by Lyra Electronics to develop an airport baggage loader powered by an electric motor.

ISO 16750-2 Testing

65V modules can perform a number of ISO 16750-2 tests. The optional embedded function generator allows the system to implement the voltage/time relationships which many of the strict standards require. Specific Tests which can be performed include:

• 4-5: Slow Decrease and Increase of Supply Voltage
• 4-6-1: Discontinuities in Supply Voltage
• 4-6-2: Reset Behaviour at Voltage Drop
• 4-6-3: Starting Profile
• 4-6-4: Load Dump
• 4-9-1: Single Line Interruption
• 4-10: Short Circuit Protection

Cranking Curve Testing

Electrical components within a vehicle's subsystem must be able to withstand a wide range of input voltage surges and drops during a start-up. The LAB-GSS can accurately recreate these conditions within a lab environment. This increases reproducibility and accuracy of results when compared to using real batteries. 

Hard to replicate conditions such as voltage cranking during a cold start can be achieved. Voltage/current and voltage/power relationships can be programmed against time where necessary. 

Powering Downhole Tools

Applications with long load lines often suffer from unintended voltage drops, such as downhole tools used in hydrocarbon exploration. The LAB-GSS's sense plus allows voltage drops to be compensated for throughout the entire length of a load line. This feature is also ideal for powering subsea devices.

Voltage Drops and Interrupts

In electronic systems sudden voltage interruptions may cause unexpected behaviour. Supply line disturbances may have several causes, including an additional switch on of large capacitive loads parallel to the supply line or a short circuit caused by loads sharing the supply. The LAB-GSS can generate many complex DC waveforms to test devices under realistic conditions to identify any potential issues.