Power analyser provides complete analysis for 3-phase motor drives
The Motor Drive Analysers (MDAs) are based on the HDO8000 oscilloscope platform and are standard with eight input channels (16 digital channels optional) with 12-bit resolution, 2.5 Gsample/sec sample rate, up to 1 GHz bandwidth and up to 250 Mpts/ch acquisition memory. A complete set of serial trigger/decode and analysis software options, and a wide variety of voltage and current probes are available to use with the MDAs.
The MDAs are aimed designers and manufacturers of motors, motor drives, variable frequency drives, variable speed drives, industrial automation and motion control equipment manufacturers. Design engineers that integrate motors into their designs (vehicles, power tools, appliances, elevators, fans, blowers, compressors, pumps, etc.) can use the product to validate proprietary controls and complete drive system designs. For three-phase systems without motors, the MDAs can be used for basic three-phase power system analysis and debug.
Positioning the instrument, LeCroy notes that a drive system combines three-phase power electronics, motor/mechanical analogue and digital sensors, and embedded controls, with a complex variety of analogue, digital, serial data and pulse-width modulated (PWM) signals. Conventional 8-bit oscilloscopes are appropriate to capture higher-speed embedded control system or power transistor activities: the [conventional] power analyser is a focussed tool for measuring input/output “black-box” drive power and efficiencies, but provides limited or no waveform capture for embedded control or drive system debug.
The MDA permits waveform captures from a drive’s three-phase power section, individual power transistors, and embedded control system, and performs coincident three-phase power analysis of the power section waveforms in one high-performance instrument, enabling debug and analysis of all aspects of the complete motor drive.
Various voltage, current, power (real, apparent, and reactive), phase angle/power factor, and efficiency parameters are calculated on acquired voltage and current waveforms and displayed in a Numerics table. The table is user-configurable and is displayed along with the acquisition waveform, and corresponds to information normally provided by a Power Analyser that measures in a “static” (steady-state) operating mode.
Additionally, the MDA provides numerical calculations under dynamic operating conditions. Waveforms showing any per-cycle measurement parameter variation can be “synthesised” and displayed by simply selecting a table value. This Waveform is time-correlated with other waveforms acquired by the MDA and can be used to correlate complex drive behaviours to other control or power system waveforms, and to debug drive system problems. Statistical detail of the measurement set can also be displayed. This additional information, LeCroy concludes, goes well beyond what is provided by a Power Analyser.
The long acquisition memory in the Motor Drive Analyeosers (up to 250 Mpts/Ch) provides capabilities for motor, motor drive, and three-phase power dynamic response analysis. For example, 25 seconds of continuous acquisition capture is possible at a sample rate of 10 Msamples/sec. This permits complete understanding of dynamic drive behaviours, such as startup, application of load, or fast changing load conditions, and correlation of drive response problems to control system instructions or power section failures. Zoom+Gate mode provides one-button setup of zoomed waveforms for all voltage, current, mechanical, or other probed signals. Then, per-cycle “synthesised” Waveforms and Numerics table results are automatically “gated” to the zoomed area, and results updated instantaneously as the zoomed area is scrolled through the original acquisition or changed in zoom ratio. This provides a quick and powerful way to gain a deep understanding of drive system behaviours and root-cause of abnormalities.
Setup capability is provided for any combination of single-phase or three-phase drive input/output, and supports both two- and three-wattmeter calculation methods and a line-line to line-neutral voltage conversion. Using the two-wattmeter method, drive input/output and motor output efficiencies can be measured using the eight inputs on the HDO8000 oscilloscope.
The Motor Drive Power Analyser software permits simple integration of nearly any type of speed, rotation or position sensor, including analogue and digital (pulse) tachometers, Brushless DC (BLDC) Hall sensor, Quadrature Encoder Interface (QEI), and Resolvers. Hall sensor and QEI signals can be integrated through digital inputs, preserving valuable analogue input channels for other signals.
Standard Teledyne LeCroy passive or active voltage probes (passive or active) and current probes may be used for power measurements. In many cases, probes required for embedded control or power section debug can be used for power measurements, making incremental investments unnecessary. Other voltage and current measurement devices (potential or current transformers, current transducers, Rogowski coils, etc.) may also be easily and simply integrated to the MDA.
The MDA is priced at $29,850 for the 350 MHz model, $32,850 for the 500 MHz model, and $35,850 for the 1 GHz model.
Teledyne LeCroy; https://teledynelecroy.com
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