Is the shielding on my current leads affecting my power measurements?
Shielded drive-to-motor cabling is often used to minimize emissions of high frequency signals during power system testing. When this full-cable shielding is used, there can be parasitic currents returned to the AC drive through the cable shields, especially if the shielding is grounded at both ends of the cable (motor and inverter). To avoid letting this return affect your current measurements, it is necessary to break the shielding at the point of the current transducer so that the parasitic currents return outside the transducer aperture. The effects of this parasitic current can be seen as lower current measurements made by the CT and power analyzer, which can lead to inconsistent and unexpected current and efficiency readings for the motor and drive system.
Related Products & Solutions
CT Series Current Transformers
In some power measurement applications, the current in the device under test is higher than what can be applied directly to the power analyzer current input terminals. Current transformers are used to step down high AC and DC currents to a lower level that can be measured directly by the power analyzer. These systems safely step down currents while preserving the highest accuracy.
Precision Power Analyzer WT3000
With 0.02% accuracy and 1MHz bandwidth, the WT3000 delivers where the highest precision measurements are required. It is the industry standard for R&D work on inverters, motor drives, lighting systems and electronic ballasts, UPS systems, aircraft power, transformer testing, and other power conversion devices.
WT1800E - High-Performance
- Power, Harmonics (THD) Measurements (up to 500th order)
- Electrical & Mechanical Efficiency of Inverters and Motors in EV and HEV
WT1800R High-Performance Power Analyzer
- Power, harmonics (THD) measurements (up to 500th order)
- Electrical and mechanical efficiency of inverters and motors in EV and HEV
WT3000E - High Accuracy
- High Accuracy Electrical & Mechanical Efficiency of Inverters and Motors in EV and HEV
- IEC Harmonics (IEC61000-3-2 & IEC61000-3-12); Voltage Fluctuations and Flicker (IEC61000-3-3 & IEC61000-3-11)
WT300E - Economy
- Standby Power Measurements, Energy Star®, SPEC Power® and IEC62301/EN50564
- Evaluation and Testing of Batteries, Home Appliances and Uninterruptible Power Supplies (UPS)
WT500 - Mid Range
- Power and Harmonic (THD) Measurements with Independent Range Controls
- Efficiency measurements of AC/DC or DC/AC Inverters & Motors
WT5000 - Precision Power Analyzer
- Precision power analyzer with superior accuracy
- 7 swappable input elements
- 4 motor inputs
- Harmonics test compliant to IEC 61000-3-2
WTViewerFreePlus for WT300/WT300E Series
The WTViewerFreePlus software captures measured numeric values, harmonic values, and waveform data. Users can view and save data on a PC using USB, GPIB, RS-232, or Ethernet.
Current Probes
Current probes allow you to measure DC or AC current. Yokogawa's selection of current probes allow measurements ranges up to 500 ARMS and bandwidths up to 100MHz.
Power Analyzers and Power Meters
Measure characteristics of devices that generate, transform or consume electricity. Also called power meters or wattmeters, these devices measure parameters such as true power (watts), power factor, harmonics, and efficiency.
Precision Current Transformers
- Regulate AC and DC with high-precision current transformers
- Current transformer meters from 60-5000 Amp peak
- Units with up to six CTs