Sunday, May 26, 2024 · 0 min read
DC-CT® Current Sensing Technology Explained
The recently introduced SIRIUS® XHS and SIRIUS® XHS-PWR power analyzers are a giant leap in data acquisition and ADC technology. They are powered by the new HybridADC technology developed specifically for the new SIRIUS® XHS data acquisition systems. We have also equipped SIRIUS® XHS-PWR power analyzers with embedded DC-CT® current sensing technology. Read further to see what DC-CT® is and what it brings to current measurement.
What is DC-CT® technology and how does It work?
DC-CT® represents an innovative principle of isolated measurement of DC and AC currents. Within a magnetic core, magnetic flux can only be measured if it is non-constant, changing, or alternating.
Since a DC current generates a constant magnetic flux the innovative principle redistributes this flux among two or more paths periodically in a single core. If we observe this magnetic flux from one path only it appears alternating and is therefore easily measured by a simple winding, which voltage is proportional to the measuring current.
This was achieved by inventing a current-controlled variable reluctance. This vital component, composed of a kind of infinity winding, is embedded into a gap-less core retaining all of the good properties of high permeability materials. This new type of flux sensor is named after the inventor - Platiše Flux Sensor. The invention is branded under the DC-CT® name which is a registered trademark of ISOTEL.
Comparing this principle to widely used Hall-based sensors inserted into a magnetic core, the DC-CT® solution does not create any air gap and thus retains a very high sensitivity and immunity to external magnetic fields. In addition, it is temperature-independent.
Comparing it to the high-end flux-gate transducers, a flux-gate method adds energy to the core to alternate the flux between the maximum and minimum operational limits of the core, which in reverse consumes a significant amount of energy. The measured current value can be extracted from the 2nd harmonics, pulse-width-modulation in self-oscillating solutions, or other methods.
High-end flux-gate current transducers require three cores instead of just one as in the case of the DC-CT® current transducer. Two of them are required for sensing, operating in opposite directions to reduce injected noise, and the third one is used to extend the AC bandwidth. Flux-gate resets a core repeatedly, while the DC-CT® is on request only to demagnetize the core.
DC-CT® compared to other current sensing technologies
We have compared DC-CT® current transducer technology to other widely used current sensing technologies.
| Type | Isolated | Range | Bandwidth | Linearity | Accuracy | Temp. drift | Consumption | |
|---|---|---|---|---|---|---|---|---|
| DC-CT | DC/AC | Yes | High | High | Excellent | Very High | Very Low | Medium |
| Fluxgate | DC/AC | Yes | High | High | Excellent | Excellent | Low | High |
| Hall | DC/AC | Yes | High | Medium | Medium | Medium | High | Low-Med |
| Shunt | DC/AC | No | Medium | Medium | Good | High | Medium | High |
| Rogowsky | AC | Yes | High | High | Good | Medium | Low | Low |
| CT | AC | Yes | High | Medium | Medium | Medium | Low | Low |
The bottom line is that DC-CT® is energy-efficient, compact size, low noise, and cost-effective. Existing products range from 2 A and up to 2000 A, with bandwidth -3dB @ 750 kHz, with target accuracy from 0.1% down to 0.01%. Other potential uses include DC/AC residual current sensors of class B+.
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SIRIUS® XHS HybridADC technology
HybridADC offers a 15 MS/s sampling rate with a high 5 MHz bandwidth acquisition on every channel. It also offers high dynamic alias-free acquisition when the sampling rate is lowered down to 1 MS/s. Everything is integrated into one single device. This is a breakthrough in the data acquisition world. One device replaces what would traditionally be two separate data acquisition devices (a high dynamic data recorder and a power analyzer).
The new HybridADC technology from Dewesoft
Integrated high-precision current transducer
SIRIUS® XHS product line also includes a device intended for electric vehicle testing called SIRIUS® XHS-PWR. The data acquisition device is designed for in-vehicle direct measurement of current, voltage, and electrical power.
It integrates innovative DC-CT® current sensing technology (DC Current Transducer) from ISOTEL. The device is suitable for very accurate current measurements such as very high current peaks as well as current leakage measurements.
The current transducer uses patented DC-CT® technology based on the Platiše Flux Sensor. DC-CT® is a registered trademark of ISOTEL. It represents the latest innovation in the current sensing technology.
DC-CT® current sensors are available with different measurement ranges - 100A, 500A, and 1000A, with a 750 kHz bandwidth @ -3dB. They offer excellent linearity, precision, accuracy, and immunity to external magnetic fields. Additionally, they have very low offsets and extremely low-temperature drift at low-power operation.
The SIRIUS® XHS-PWR device can also directly measure the voltage up to 2000V peak (CAT II 1000V) with up to 5 MHz bandwidth.
For more information check the full SIRIUS® XHS-PWR specs.
The SIRIUS® XHS-PWR is extremely compact and perfect for direct installation into a vehicle with the power lines leading through the device. It has an IP65 degree of environmental protection which allows usage in harsh environments and during rough drives.
