Dynamic Response of AC Transducers
Quotes From AS384-1973 Transducers for Electrical Measurement
6.6. Purity Of Output
6.7. Dynamic Response
Dynamic Response of AC Transducers
According to the Australian Standard 1384-1973 "Transducers for Electrical Measurement" (sections reproduced at the end of this article) the standard response time of a transducer is 500ms.
The standard response time of a transducer can be changed but there is a trade off in response time versus ripple in the DC output. For faster response the ripple increases. (Refer to "ripple" definition at end of article).
The trade of between response time and ripple can be shown by the graph below which is typical for the AC current transducer (ACT141) or AC voltage transducer (AVT145).
For convenience we can also relate ripple verses T90 response time.
The T90 time is defined as follows:
- "For an input step of 100%, the T90 time is the time taken for the output to reach 90% of its final value".
Faster response requires factory changes and follows the ripple curve.
Quote AS1384-1973 "Transducers for Electrical Measurement"
6.6. Purity Of Output
6.6.1 Maximum Peak-to-Peak Value. The peak-to-peak value of the combined ripple, hum and noise content in the DC output of a transducer, measured in the band from zero to 10kHz, shall not exceed the class index when expressed as a percentage of the full rated DC output at any value of measured quantity, output load, temperature, auxiliary supply voltage and frequency within the specified ranges.
6.6.2. Other Requirements. More stringent requirements, e.g. the requirements for unfiltered output, may be arranged between purchaser and manufacturer.
NOTE: Attention is drawn to the interrelation between the degree of output filtering and the response time.
6.7. Dynamic Response
6.7.1 Response Time. For any step change of the measured quantity within the measuring range, the output shall within 500ms reach and remain within a band about the final value; the width of the band shall be equal to ±2 percent of the final change of output.
NOTE: A response time of 500ms may not be suitable for all applications. Where a different response time is necessary, agreement should be reached between purchaser and manufacturer.
6.7.2 Overshoot. For any step change of the measured quantity within the measuring range, the maximum change in output shall not exceed the ultimate change by more than 2 percent.