All measuring instruments are subject to limitations. The purpose of this technical note is to explain some of those limitations and to help the engineer maximise the many advantages of PEM’s CWT current probes based on Rogowski technology. This note discusses the ability of the CWT Rogowski probe to reject interference from voltage fields coupled to the Rogowski coil, as these fields vary with both magnitude and frequency. This is particularly relevant when using Rogowski coils to measure current in fast switching semiconductors where voltage transitions close to the coil result in a harsh measurement environment.
This document covers:
- Screened (shielded) vs. unscreened Rogowski coils
- CWT ‘HF’ screened Rogowski probes
- Voltage rejection with frequency – Common mode voltage rejection
- ‘Real-world measurements’ in fast switching power converters
- CWT Ultra-mini – voltage immunity
- Large magnitude 50/60Hz fields
- Peak voltage coil insulation ratings.
Technical notes relating to CWT, CWTHF, CWTMini50HF, CWT Ultra-mini, CWTUM-S, CWTUM-F, CWTUMHF-F, CMC and CWTLF.
The purpose of these technical notes is to explain any limitations of the device and to also assist the engineer in maximizing the many advantages of the CWT, CWTHF, CWTMini50HF, CWT Ultra-mini, CWTUM-S, CWTUM-F, CWTUMHF-F, CMC and CWTLF.
We recommend that you use this instruction sheet in conjunction with the products short-form datasheets and instruction sheets.