US firm Barth electronics have released an ultra-wideband high voltage attenuator designed for measurement of signal rise times below 100ps. The 2240-BENFP attenuator covers DC to 7GHz. The input connector is the new high voltage/high speed Barth 454 connector. The output is a standard female N-type.
Barth attenuators such as the 2240-BENFP are typically used to measure HV pulses with fast rise times in pulse power applications such as flash X-ray, kicker systems or high power microwave systems. Measuring fast rise times at 200mV is hard because of the requirement to minimise the size in order to reduce stray capacitance and inductance. However, at 50kV, you need space to hold off the voltage. The combination of large size with lower stray capacitance and inductance is unique to Barth Electronics. Here at PPM Power we think that a 50kV attenuator covering 7GHz with <100pS rise time is a pretty big deal.
PPM supply a variety of high-performance attenuators from Barth. Typical applications include:
- EMP simulation
- EMP, ESD and lightning testing
- Impulse radar
- High power microwave
Custom products also include TEM Antennas, voltage probes, high voltage pulse connectors and pulse resistive probes.
Barth 2240 HV attenuator specification
||20/1 +/- 5% (26dB)
|Maximum Input Voltage
||25kV, 160ns FWHM
50kV, 40ns FWHM
|Peak Input Energy
||2.0 Joules (Watt Seconds)
|Average Input Power
||50 Ohm +/- 1%
|Risetime through Unit
||DC to 7.0GHz
|Reflection – TDR
||Input <4% to a 100ps rise time step
||<3% to a 100ps rise time step
||<1% at any voltage
||4134mm long x 492mm wide x 787mm high
Attenuators from PPM
High power switch manufacturer Astrol Electronic has developed a new series of DC breakers with up to 1500V DC voltage capability. The liquid cooled units allow bi-directional current flow and can be used in high or low side power switching. Current ratings range from 500A to 5kA. Switch-off current ranges up to 20kA. The DC breakers are designed to maximise flexibility when integrating DC-grids and protect against short-circuit currents in any part of the grid. Various voltage and current levels are realized using a modular structure and different configurations based on 3.3kV, 4.5kV and 6.5kV Insulated Gate Bipolar Transistor (IGBT) and diode modules.
Fast Fault Interruption
A solid-state breaker must interrupt the full current in microseconds. With such a time constraint, local fault protection must be performed autonomously by the switch control system without the need for external control or fault detection. In addition to rapid over-current protection, the breaker can be programmed to open according to a time-current profile. This allows the overall system to reconfigure the behavior of the DC-Breaker within certain pre-defined boundaries. The fast opening time of solid-state breakers limits the fault current and minimises the negative impact on the load. The current does not reach damaging levels and can be interrupted without forming an arc. Voltage reversal is therefore not required.
Self-diagnostics and control interface
The internal self-diagnostic capability of the DC breaker units includes the gate drive unit as well as coolant temperature and pressure at both inlet and outlet. The interface to the overall controller is optical (glass or plastic) Modbus-TCP. However, other protocols are available on request.
- DC-Voltage Capability up to 1500V
- Current rating 0 – 5kA
- Switch-off current up to 20kA
- Very short off time in μs range
- Totally isolated to the main grid
- Can be used in high or low side power switching
- Bidirectional current flow
- Liquid cooling
- Internal self-diagnostic capability
- Gate Drive Unit
- Water In- and Outlet Temperature
- Water In- and Outlet Pressure
- Interface to overall controller
- Optical (Glass or Plastic)
- Other protocols on request
- DNV-GL type approval (pending)
High voltage switches
LEM have announced a 2000A closed loop current transducer which uses a new approach to ripple cancellation at the fluxgate drive frequency. Reduced ripple means an increased resolution and a higher signal to noise ratio than previous generations of current transducer.
The IN2000 fluxgate type current transducer integrates a high performance DSP in the feedback loop to maximise signal processing in the digital domain. This ensures immunity to temperature effects, interference and supply voltage variation after the ADC. Offset and offset drift are also significantly improved.
Integrated DSP shapes the drive waveform
The DSP reduces fluxgate drive signal interference and ripple at a fixed frequency of 16kHz. Instead of simply switching the fluxgate voltage between positive and negative values, the drive waveform is shaped to reduce higher frequency harmonics. The remaining interference is eliminated by driving a ripple compensation coil. The DSP also includes flash memory which stores calibration parameters for individual transducers. Ripple compensation is kept constant using a local loop to keep the fluxgate drive constant. Earlier transducers allow the fluxgate excitation frequency to vary in order to keep the current amplitude constant.
High accuracy and low noise over temperature
The IN2000 delivers high accuracy and low noise over a wide temperature range. After calibration, the remaining peak-to-peak ripple is less than 50ppm (0.005%) relative to the full scale transducer output between -40 and +85 degC.
Comparison with previous generation
The graph below compares the IN2000 transducer output ripple at the fluxgate drive frequency to a previous generation transducer. Before calibration, the ripple of the compensation circuit is comparable with the spikes of the previous generation. After calibration, the ripple disappears into the noise at the output.
Shielding from interference
The IN2000 uses a metallic housing to shield from external sources of interference. EMC immunity is further improved by locating the fluxgate inside the primary magnetic circuit.
Overload and supply voltage fault detection
The IN2000 reacts to overload conditions and is self-protected by software that checks external and internal supply voltages. When a fault is detected, the IN2000 gives a status output on a dedicated connector pin.
The IN2000 has a measuring range up to 3000A and is intended to deliver the high levels of performance required for increasingly demanding applications such as test equipment, medical equipment, precision motor control and metering.
How good is a Power Ring capacitor?
The Power Ring design results in lower losses, lower inductance and a higher ripple current rating than traditional film capacitor technology. The ring shape provides extremely low internal losses (ESR) and dramatically lowers the inductive properties (ESL). SBE’s Power Ring capacitors show ESR values as low as 0.15 mOhm for a 1000µF – 600V DC Link.
The graph of temperature versus ripple current (above) illustrates the huge improvement in thermal performance delivered by the Power Ring design versus a conventional array of film capacitors. This performance improvement translates to a more efficient use of microfarads where high ripple current is an issue. Design can be optimised for current-handling rather than having to “bulk up” on capacitance only for current handling survival and lifetime requirements – a strategy which has the side-effects of increased cost and size.
How do they do it?
The ultra-low ESR is achieved by shortening the current path between the electrodes. SBE’s patent-pending segmented end spray approach divides the metal end spray into “floating” segments (see diagram). Unlike conventional capacitors, the loss between film and end spray metalisation is so low that current in the end spray can be the dominant loss contributor. The capacitor element ESR can be as low as 50μΩ and the ESR of the end spray/braid can be less than 10μΩ.
Power ring v snubber capacitor
A Power Ring DC link capacitor with integrated bus bar offers a loop inductance that can eliminate the need for a snubber circuit. Snubber capacitors get very hot since they are connected to the IGBT pins (often the hottest point other than under the die itself) and are almost never directly cooled due to the difficulty of connecting cooling plates. Their small size and poor cooling mean snubber capacitors are usually the weak link in the reliability chain for an inverter.
As usable operating voltage increases there can be a tendency to add a snubber to get every bit of safe operating voltage out of a system. The integrated Power Ring capacitor is a more effective method of reducing overshoot, and therefore increasing safe operating voltage, without compromising reliability or system lifetime.
A cooler DC link capacitor means a longer lifetime. A lower ESL means reduced overshoot and undershoot which reduces stress. Removing the requirement for a snubber capacitor means lower costs, a smaller design and a longer lifetime.
Power Ring capacitors
GT series – snubber capacitors
KPST series snubber capacitors
Capacitors from PPM Power
Compact solution for high power pulsed applications
ESP resistors from EBG provide a highly compact solution for high power, pulsed, low frequency applications such as:
- Inrush current limiting
- Capacitor pre-charge and discharge
- Motor control units
- Power supplies,
- Battery charging systems
- Inverter drives.
Right now, these resistors are popular in electric vehicle subsystems as pre-charge resistors and in-rush current limiting devices for industrial power control systems.
Large energy pulses
The special resistive element provides a highly reliable, non-inductive current path capable of handling large energy pulses up to 3300 joules over one second.
The EBG ESP resistor has a very small footprint when compared with thick film, ceramic and wire wound resistors with equivalent peak power ratings, an essential feature for applications where where space is very limited such as electric vehicles or military systems.
Resistor technology comparison table
||Peak Power Rating
Superb build quality
The resistor has superb build quality with large end caps and M4 threads for multiple mounting options. Two diameter sizes are available: 14mm and 20mm. Both sizes are 62mm in length with resistance values between 10 ohms and 1K ohms. Tolerances are +/-5% or +/-10%. If you require tighter specifications please contact a member of the PPM Power technical sales team on 01793 784389.
The PH-A280 series of high voltage input DC-DC converters from TDK-Lambda are now available with 300W output. The DC-DC power modules have a range of 200 to 425Vdc, and are suitable for use in applications using a 380V DC bus such as data centres, telecommunications and renewable energy. The four new models are rated at 12V / 25A, 24V / 12.5A, 28V / 10.8A and 48V / 6.3A. These extend the 50 to 150W PH-A280 product range which already includes outputs of 3.3V, 5V, 12V, 24V, 28V and 48V.
Greater Adjustment Range
The 300W models have a greater adjustment range of -60% to +20% to accommodate non-standard voltages and can provide full load with -40°C to +100°C baseplate temperatures. The range offers efficiencies of up to 92%,
The units follow the industry-standard half-brick package (61.0 x 12.7 x 57.9mm).
The converters can also be conduction cooled making them suitable for use in sealed outdoor enclosures or liquid cooled applications.
Five year warranty
All PH-A280 modules include:
- Five-year warranty,
- Remote on-off
- Over-current and over-voltage protection.
The series is fully isolated with an input to output isolation of 3,000Vac.
Certified to IEC/EN 60950-1, UL/CSA 60950-1 with CE marking for the Low Voltage and RoHS2 Directives.
High Voltage DC-DC power supplies
Overview of power supplies available from PPM
Nanocrystalline is a soft magnetic material composed of 82% iron which has been dubbed the future of magnetic materials in power electronics. Higher permeability means lower loss transformers, which can translate to large reductions in size and weight.
Lower losses, smaller size and reduced weight
The losses of a Nanocrystalline core can be up to two-thirds less than an equivalent Nickel Supermalloy core and up to 80% less than for toroid geometries. Less power is dissipated by the transformer (or inductor) and means the size of cooling components can be reduced.
Ease of switch over from other materials
Nanocrystalline can be formed into any shape and therefore offers a drop-in replacement for existing cores manufactured from other materials, such as Supermalloy or ferrite.
Nanocrystalline v Supermalloy
Nanocrystalline material is more suitable than Supermalloy in applications such as high frequency/broadband transformers, broadband current sensors, high frequency filter chokes and pulse transformers because nanocrystalline offers:
- High permeability over a broad frequency range
- High saturation flux density
- Low losses
Soft magnetic cores from PPM Power
PPM Power can supply tape-wound soft magnetic cores manufactured by MK Magnetics from a range of materials, including grain-oriented silicon steels, 50% and 80% nickel alloys, amorphous material, cobalt alloys and nanocrystalline. Cores up to 1.8m x 1.8m / 1800Kg and strip widths up to 0.6m are possible.
Potential magnetic core weight reduction (2000 Gauss, 20kHz)
Comparison of magnetic materials
|Grain Oriented Silicon Steel
|Standard Crystalline Permalloy
|Advanced Silicon Steel
|High Performance Ferrite
|Advanced Crystalline Permalloy
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