High measuring speed, exceptional precision, and optimal resolution all at once...
That's not a contradiction!
Electrical tests always take test time in the tension between maximum precision and the fastest possible test time . While electrical safety tests with their fixed minimum test times offer little potential for optimization, the possibilities for improving measurement speed in functional and quality tests are quite different:
measurement speed
The timing of functional and quality tests is determined by the product characteristics and our own quality standards— but not exclusively! The technological approach to test equipment design is particularly important here.
Testing devices are usually built-in into time-optimized production chains. They must be fast and reliable and must not cause bottlenecks in the process.
Their requirement: "The testing device must deliver maximum performance in all operating conditions."
This applies to all software and, in particular, to the efficiency of each individual test method. All safety checks and most functional and quality checks are essentially based on electrical measurements that are evaluated during and, at the latest, at the end of the test step.
The highest possible measurement speed is crucial for the overall measurement duration. However, this must not compromise the precision of the measurement!
Exceptional precision: From analog signal to digital measurement value – details for the tech enthusiast
All calculations in the test device are based on digital measured values.
How do you get from an analog signal to a digital measured value?
Analog-to-digital converters are used for this purpose.
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These semiconductor chips convert the analog signal curve into individual digital values. An individual digital value is also referred to as a sample. If, for example, 1000 individual values are measured per second, this is referred to as a sampling rate of 1 kSps.
The graph clearly shows that the precision of a measurement depends on the number of samples taken in a given period and on the staircase-like resolution of the analog signal. In a nutshell: result precise and repeatable measurement results.
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Optimal resolution – maximum measurement accuracy
High measurement accuracy can only be achieved at the expense of measurement speed, and vice versa. This is a fundamental technical law. This has been the case in the past and will continue to be so in the future.
This becomes particularly clear when using a highly accurate bench/built-in multimeter in a test device. Some test device manufacturers like to use such multimeters. The accuracy is certainly good, but the measurement speed is often very modest. And that then contradicts the requirement that an automatic test device should not be a time bottleneck.
Another disadvantage of multimeters is that they do not provide individual sample values, but only completely processed effective or DC voltage values. This results in the loss of a lot of very important detailed information for special signal analyses and quick response options to highly dynamic test events.
And what SCHLEICH solution?
SCHLEICH always developed both the measurement technology hardware and the software itself.
Thisensures that the measurements are perfectly adapted to the precision required by the individual test methods.
The measurement speed, combined with high measurement accuracy, forms a perfect unit.
Our goal is to provide the fastest testing machines provide without compromising on measurement accuracy.
– Dipl. Ing. Martin Lahrmann
New three-phase current measurement technology
Function tests are performed in space to the highest currents. Currents from 0.1 mA to over 1 kA are not uncommon. This is an enormous dynamic range. Slow measurement technology with time-consuming autorange switching is unsuitable here. This is another significant disadvantage of multimeters.
The measurement must therefore be performed with a high sampling rate and high resolution. It must determine the effective values of the half or full periods as well as the DC voltage component with network period accuracy.
SCHLEICH has always been strong. But even proven technology can be improved with new technical possibilities.
That's why we have a extensive upgrade our three-phase measurement technology The result even greater precision and speed. Naturally, everything was developed entirely in-house.
Our fundamental principle is that we must always remain in control and not be dependent on purchased individual components and their disadvantages.
Key data for three-phase measurement technology
| voltage measurement | from 0.1 V to 600 VULN – measured to a virtual zero point |
| from 0.1 V to 1000 VULL | |
| potential-free measurement | |
| Resolution up to 24 bits | |
| Class accuracy better than 0.1 | |
| power range | von < 0,1 mA bis > 1000 A |
| potential-free measurement | |
| Current transformer on board | |
| External current transformers above 1000 A, e.g., LEM / DANFYSIK | |
| external current shunts | |
| Resolution up to 24 bits | |
| Class accuracy better than 0.1 | |
| sampling rate | up to 2000 kSps |
| Ethernet | 1 gigabit |
| measurement | 2-channel single-phase measurement, instantaneous – 1xU plus 1xI absolutely time-synchronous |
| 6-channel three-phase current measurement, instantaneous – 3xU plus 3xI absolutely time-synchronous | |
| 12-channel measurement, instantaneous – 3xU plus 3xI plus 6 free channels, absolutely time-synchronous | |
| performance measurement | instantaneous power |
| Apparent power, active power, reactive power, instantaneous | |
| Power factor cos φ | included |
