AC, DC and AC+DC
Multiple output configurations support supplying, loading and simulating both AC and DC devices under test.
KGS – Bidirectional AC/DC Power Source and Regenerative Load up to 1,080 kVA
For realistic grid, converter and avionics testing in high-power test systems.
A SiC MOSFET PWM power stage is controlled by a dual-DSP/FPGA architecture and records measured values at 10 kS/s. Independently controlled phases and the modular cabinet design combine high-dynamic grid and load simulation with a scalable platform for complex test systems.
Regenerative load modes
CC, CP, CR, rectifier, RLC and RCD functions reproduce linear and non-linear load characteristics.
Grid events and harmonics
Sequences, phase unbalance, harmonics and inter-harmonics reproduce defined grid conditions in repeatable test procedures.
Automated integration
LAN, RS485 and ATI are standard; SCPI, Modbus/ASCII, TTL and master-slave communication support test-system integration.
Personal project consultation
Do you need support selecting the right power supply? Our technical specialists will provide personal advice tailored to your application.
Select the appropriate technical configuration or access product documentation directly.
ART. NO.
Description
Current [A]
Power [P]
Voltage [V]
KGS 15
|
Description
KGS SiC AC/DC source and load, 15 kVA, AC 450 V L-N, DC 636 V, 70 A, DC–5 kHz
|
Current [A]
70
|
Power [P]
15000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS 45
|
Description
KGS 45 SiC AC/DC source and load, 45 kVA, AC 450 V L-N, DC 636 V, 70 A/phase, DC–5 kHz
|
Current [A]
70
|
Power [P]
45000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS 90
|
Description
KGS 90 SiC AC/DC source and load, 90 kVA, AC 450 V L-N, DC 636 V, 140 A/phase, DC–5 kHz
|
Current [A]
140
|
Power [P]
90000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS 135
|
Description
KGS 135 SiC AC/DC source and load, 135 kVA, AC 450 V L-N, DC 636 V, 210 A/phase, DC–5 kHz
|
Current [A]
210
|
Power [P]
135000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS 180
|
Description
KGS 180 SiC AC/DC source and load, 180 kVA, AC 450 V L-N, DC 636 V, 280 A/phase, DC–5 kHz
|
Current [A]
280
|
Power [P]
180000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS 270
|
Description
KGS 270 SiC AC/DC source and load, 270 kVA, AC 450 V L-N, DC 636 V, 420 A/phase, DC–5 kHz
|
Current [A]
420
|
Power [P]
270000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS 360
|
Description
KGS 360 SiC AC/DC source and load, 360 kVA, AC 450 V L-N, DC 636 V, 560 A/phase, DC–5 kHz
|
Current [A]
560
|
Power [P]
360000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS 450
|
Description
KGS 450 SiC AC/DC source and load, 450 kVA, AC 450 V L-N, DC 636 V, 700 A/phase, DC–5 kHz
|
Current [A]
700
|
Power [P]
450000
|
Voltage [V]
450
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS Custom
|
Description
KGS Customized Customized SiC AC/DC source and load, optionally up to 900 V L-N, project-specific configuration
|
Current [A]
10000
|
Power [P]
10000000
|
Voltage [V]
50000
|
4Q AC/DC Amplifier
Technical Data
Product category
AC Bidirectional
AC Electronic Load
AC Power Supply
Type of AC source
Current-controlled CC
Source + Load
Single-/Three-phase
KGS overview
The KGS combines a bidirectional AC/DC power source and regenerative electronic load in a modular cabinet platform based on SiC MOSFET PWM technology. System ratings range from 15 kVA to 1,080 kVA, while the standard model table covers KGS 15 through KGS 540. AC operation provides frequencies from DC to 5 kHz and up to 450 V L-N. DC and AC+DC output, regenerative load operation, grid simulation and freely programmable three-phase scenarios are also supported. Each phase can be controlled independently or connected in parallel for single-phase operation. The cabinet design, touch-panel control, measurement acquisition and remote interfaces support development laboratories, power-electronics validation, ATE installations and customised high-power test systems.
Key benefits
Bidirectional power flow
Source and sink operation are provided by the same platform, allowing power to be delivered, absorbed and regeneratively returned.
Wide frequency range
Operation from DC to 5 kHz supports grid, avionics and frequency-converter testing at variable frequencies.
Flexible phase configuration
Three independently programmable phases support balanced, unbalanced and parallel single-phase output configurations.
Integrated load simulation
Regenerative CC, CP, CR, rectifier, RLC and RCD modes reduce the need for separate AC load equipment.
Power-amplifier function
An external ±5 V analogue signal can control the output with a delay of no more than 20 µs.
Modular power scaling
Multiple power ratings and optical master-slave communication support larger centrally controlled test installations.
Operating principle of the bidirectional AC/DC power source
In source operation, the KGS generates programmable AC, DC or AC+DC output. Voltage, current limits, power, frequency and phase angle can be defined according to the selected operating mode. Its bidirectional architecture enables transitions between power delivery and power absorption, making the system suitable for four-quadrant testing of grid-connected power electronics.
Regenerative load operation includes CC, CP and CR modes as well as a rectifier mode with adjustable crest factor. More complex devices can be tested using phase-programmable RLC and RCD equivalent circuits. In constant-current operation, the KGS uses true current-feedback control to maintain the selected current during rapid changes in DUT impedance.
Independent phase control: Voltage, phase angle and selected load parameters can be configured separately for phases A, B and C. This supports reproducible unbalance, phase-shift and fault-condition testing.
Power range and technical operating envelope
The AC output limits depend on the selected frequency. The following values apply to each 15 kW power module. At higher frequencies, the available output voltage and, in some ranges, the maximum current are reduced.
| Frequency range | Maximum AC voltage | Maximum current per module | Practical classification |
|---|---|---|---|
| DC to 65 Hz | 450 V L-N | 70 A | Full voltage range for conventional grid and low-frequency testing. |
| 65 to 1,000 Hz | 375 V L-N | 70 A | Extended-frequency operation with a reduced voltage range. |
| 1,000 to 2,000 Hz | 350 V L-N | 70 A | High-frequency supply scenarios within the specified operating envelope. |
| 2,000 to 3,000 Hz | 250 V L-N | 60 A | Voltage and current are further reduced as frequency increases. |
| 3,000 to 5,000 Hz | 150 V L-N | 50 A | Upper frequency range for specialised AC and avionics testing. |
Standard models
| Model | Output power | Maximum AC output | Maximum DC output | Dimensions W × D × H | Weight |
|---|---|---|---|---|---|
| KGS 15 | 15 kVA | 450 V L-N, 70 A | 0 to 636 V, ±70 A | 800 × 900 × 1,100 mm | 300 kg |
| KGS 45 | 45 kVA | 450 V L-N, 70 A/phase | 0 to 636 V, ±70 A | 800 × 900 × 1,500 mm | 460 kg |
| KGS 90 | 90 kVA | 450 V L-N, 140 A/phase | 0 to 636 V, ±140 A | 900 × 900 × 2,200 mm | 900 kg |
| KGS 135 | 135 kVA | 450 V L-N, 210 A/phase | 0 to 636 V, ±210 A | 1,600 × 900 × 1,800 mm | 1,050 kg |
| KGS 180 | 180 kVA | 450 V L-N, 280 A/phase | 0 to 636 V, ±280 A | 1,600 × 900 × 2,200 mm | 1,200 kg |
| KGS 270 | 270 kVA | 450 V L-N, 420 A/phase | 0 to 636 V, ±420 A | 2,400 × 900 × 2,200 mm | 1,800 kg |
| KGS 360 | 360 kVA | 450 V L-N, 560 A/phase | 0 to 636 V, ±560 A | 3,200 × 900 × 2,200 mm | 2,400 kg |
| KGS 450 | 450 kVA | 450 V L-N, 700 A/phase | 0 to 636 V, ±700 A | 4,000 × 900 × 2,200 mm | 2,900 kg |
| KGS 540 | 540 kVA | 450 V L-N, 840 A/phase | 0 to 636 V, ±840 A | 4,800 × 900 × 2,200 mm | 3,600 kg |
Maximum DC output voltage: The KGS provides up to 636 V DC, depending on the selected model configuration.
The platform extends to 1,080 kVA. The table above contains the published standard models up to 540 kVA. Higher ratings are configured as scaled system solutions.
Dynamics, accuracy and control behaviour
The KGS combines a fast PWM power stage with digital DSP/FPGA control. Voltage and current ramps are programmable for dynamic tests. The ATI input also allows the system to operate as a wide-bandwidth power amplifier.
| Parameter | Value | Technical significance |
|---|---|---|
| Small-signal bandwidth | 10 kHz | Supports the reproduction of rapid signal and setpoint changes. |
| ATI operating delay | ≤ 20 µs | Short delay between the external analogue signal and the power output. |
| Voltage slew rate | 5 V/µs | Defines the maximum rate of change of the output voltage. |
| Current slew rate | 0.5 A/µs | Relevant for rapid current profiles and load changes. |
| Measurement display and storage | 10 kS/s | Records output and system parameters for analysis and documentation. |
| Load and line regulation | 0.1% FS each | Specifies variation caused by load or AC input changes. |
Frequency-dependent AC accuracy
| Frequency range | Voltage accuracy | Current accuracy | Power accuracy | Phase-angle accuracy |
|---|---|---|---|---|
| DC to 45 Hz | 0.2% FS | 0.3% FS | 0.3% FS | < 1° |
| 45 to 70 Hz | 0.1% FS | 0.1% FS | 0.1% FS | < 0.1° |
| 70 Hz to 2 kHz | 0.2% FS | 0.3% FS | 0.3% FS | < 1° |
The frequency accuracy is 0.01% FS + 0.01 Hz. Total harmonic distortion depends on frequency and operating point, ranging from less than 0.3% FS at low frequencies with a resistive load to less than 2% FS between 4 and 5 kHz.
Operating modes and programmable test functions
| Function | Description | Typical benefit |
|---|---|---|
| AC, DC and AC+DC | Pure AC or DC output and AC waveforms with a superimposed DC component. | Cover multiple DUT and supply topologies with one system. |
| CV and true CC operation | Voltage control or current control using true current-feedback regulation. | Stable current profiles during rapid changes in DUT impedance. |
| Sequence mode | Programmable steps for voltage, frequency, phase, ramp time and dwell time. | Repeatable grid faults, interruptions and dynamic operating states. |
| List mode | Complex command sequences with loops, output enables and phase-dependent transitions. | Automated endurance testing and extensive test profiles. |
| Harmonics | Generation up to the 100th harmonic at 50 or 60 Hz with phase-specific amplitude and angle settings. | Testing immunity and behaviour under distorted grid voltage. |
| Inter-harmonics | Programmable frequency, amplitude and phase for up to eight inter-harmonic settings. | Reproduction of non-synchronous disturbance components and frequency sweeps. |
| Regenerative AC load | CC, CP, CR and rectifier operation with adjustable crest factor. | Simulation of resistive, inductive, capacitive and non-linear loads. |
| RLC and RCD simulation | Twelve RLC and four RCD topologies with independently programmable phase parameters. | Testing inverters, UPS systems and AC power supplies without a separate load bank. |
| Short-circuit testing | The output supports defined short-circuit tests and includes programmable current limits. | Verification of protection behaviour in inverters and other grid-connected DUTs. |
| Bi-polar DC source | Optional bipolar DC output for positive and negative voltage ranges. | Testing bipolar-powered components and systems requiring polarity reversal. |
Typical applications
By combining grid simulation, programmable source operation, regenerative loading and measurement acquisition, the KGS can both supply and load a broad range of energy and power-electronics components.
PV inverter and grid simulation
The KGS reproduces voltage dips, frequency changes, unbalance, harmonics and short-circuit conditions for inverter testing.
Energy-storage converters
Bidirectional converters can be validated under changing grid conditions, power-flow directions and programmed voltage or frequency profiles.
UPS and AC power-source testing
RLC, RCD, rectifier and crest-factor modes load UPS systems and power sources with defined linear or non-linear characteristics.
Avionics and aircraft-bus simulation
Normal operation, transfer, interruption, start-up and fault states can be reproduced for MIL-STD-704-related test scenarios.
Automated test equipment
SCPI commands, sequences, TTL triggers and measurement queries support integration into automated development and validation systems.
Production and end-of-line testing
Repeatable test files, remote control and central measurement display support automated functional and protection testing in production.
Interfaces, software and automation
The local Windows GUI is installed on the 12-inch touch panel and can also be used on a connected control PC. Parameters, sequences, measurements, harmonic analysis, waveforms and fault states are managed through a common interface.
| Interface or function | Status | Application |
|---|---|---|
| LAN | Standard | Remote control, control-PC communication and integration into automated systems. |
| RS485 | Standard | Robust serial remote control and multi-drop communication; default setting 9,600 baud, 8N1. |
| ATI | Standard | Analogue BNC control input with ±5 V for operation as a power amplifier. |
| TTL trigger out | Integrated | Trigger output following voltage or frequency changes for synchronised oscilloscope acquisition. |
| SCPI | Supported | Programming of output, measurement queries, protection values, sequences, harmonics and inter-harmonics. |
| Modbus/ASCII | Supported | Protocol-based control and integration into higher-level automation environments. |
| Remote sense | Integrated | Compensation of voltage drop between the power output and the DUT. |
| Master-slave | Integrated | Optical communication between paralleled units with matching power, voltage and current ratings. |
| External emergency stop | Integrated | Connection of a customer-supplied emergency-stop switch to the test-system safety chain. |
| GUI and measurement acquisition | Standard | Local operation, real-time measurements, harmonic analysis, waveform display, storage and fault indication. |
Parallel operation, single-phase output and scaling
Units with matching power, voltage and current ratings can be operated in a master-slave arrangement. Communication between master and slave uses an optical connection, while the AC input and power-output connections are also paralleled according to the installation requirements. The maximum number of units depends on the configured system.
Paralleled units
Matching KGS configurations can be coupled as master and slave to scale power and output current.
Single-phase configuration
The three phase outputs can be connected in parallel, providing a single-phase output with three times the phase current.
System power ratings
The modular platform supports total system ratings up to 1,080 kVA.
| Option or configuration | Description |
|---|---|
| -BP | Optional bipolar DC source for positive and negative output voltages. |
| -HV900 | Increased output voltage up to 900 V L-N, subject to technical consultation. |
| 380 / 400 / 480 | Model configuration for 380 V, 400 V or 480 V L-L input voltage, each with a ±10% tolerance. |
Installation and infrastructure
The KGS is installed as a forced-air-cooled cabinet system. AC input, circuit protection, cable cross-sections and switching equipment must be selected according to the chosen model and configured power rating.
| Requirement | Specification | Planning note |
|---|---|---|
| AC input | 380 V, 400 V or 480 V L-L, each ±10% | The input version is defined by the model configuration. |
| Phases and protective earth | 3P+N+PE or 3P+PE | Neutral-conductor requirements and connection details must be confirmed for the project. |
| Input frequency | 47 to 63 Hz | The intended supply network must remain within this range. |
| Power factor | 0.99 | Value for the AC input. |
| Input current distortion | THDi < 3% FS | Grid-side specification. |
| Efficiency | ≥ 85% | No separate regenerative efficiency rating is specified. |
| Cooling | Forced-air cooling | Allow at least 600 mm of clearance from walls or other equipment for ventilation. |
| Operating temperature | 0 to 40°C | Operate only in a suitable indoor environment. |
| Humidity | 20 to 90% RH, non-condensing | Avoid condensation and corrosive environments. |
| Ingress protection | IP21 | The system is intended for indoor installation. |
| Cabinet base | Wheels below 1,400 kg total weight; steel-channel base above this weight | Check transport routes, floor loading and installation space at an early stage. |
Safe connection: Protective earth must be connected before any AC input or output conductor. Installation and changes to power wiring must only be performed in a de-energised state by qualified personnel.
Protection and safety functions
Overvoltage protection
An adjustable peak-value limit switches off the output when the programmed voltage threshold is exceeded.
Overcurrent and current limiting
Overcurrent protection and a separately programmable current limit protect the system and DUT from excessive current.
Overpower protection
The output is switched off when measured power exceeds the configured protection value.
Temperature monitoring
Internal heat-sink temperatures are monitored and the output is disabled if an excessive temperature is detected.
Local and external emergency stop
A front-panel emergency-stop button and external interface support integration into the system safety chain.
Soft start and status monitoring
Soft start limits the power-on impulse, while status indicators and fault words support commissioning and diagnostics.
CE conformity is specified in accordance with EN 62040-1 and EN 62040-2. Suitability of a configured system for a specific standardised test must be evaluated against the complete test setup.
Frequently asked questions about the KGS
Can the KGS operate as both a source and a regenerative load?
The bidirectional power stage supports source and sink operation. The required operating mode is selected through the GUI or remote-control interface.
What power ratings are available?
The modular platform covers 15 kVA to 1,080 kVA. The published standard model table extends to the 540 kVA KGS 540.
Is 450 V L-N available over the complete frequency range?
No. The 450 V L-N rating applies up to 65 Hz. Above this frequency, the maximum available voltage is reduced according to the frequency-dependent operating envelope.
Can the KGS supply a single-phase DUT?
Yes. The three phase outputs can be connected in parallel in accordance with the installation requirements. The resulting single-phase current is three times the individual phase current.
Which functions are available for grid-simulation testing?
Programmable parameters include voltage, frequency, phase angle, ramps, output phase angle, voltage dips, interruptions, unbalance, harmonics and inter-harmonics.
How can the KGS be integrated into automated test systems?
LAN, RS485 and ATI are standard. SCPI, Modbus/ASCII, TTL triggering, measurement queries and optical master-slave communication are also available.
Does the series support bipolar DC output?
Bipolar DC operation is available as the -BP option. Power, voltage and connection data must be confirmed for the selected configuration.
Which AC input configurations are available?
The standard input configurations are 380 V, 400 V and 480 V L-L, each with a ±10% tolerance and 3P+N+PE or 3P+PE connection.
Technical consultation and project enquiry
Selecting a KGS configuration depends on power, voltage, current, frequency range, operating modes, AC input and the required test scenarios. ET System supports model selection, electrical-infrastructure planning, automation and integration into a complete test system.
- Configuration of source, sink and grid-simulator functions
- Verification of the frequency-dependent operating envelope
- Planning of parallel operation and single-phase output
- Integration of interfaces, safety circuits and measurement equipment
