IEEE C37.301-2009 IEEE Standard for High-Voltage Switchgear (Above 1000 V) Test Techniques—Partial Discharge Measurements.
3.9.4 superposition error caused by the overlapping of transient output pulse responses when the time interval between input current pulses is less than the duration of a single output response pulse. Superposition errors can be additive or subtractive depending on the pulse repetition rate of the input pulses. In practical circuits, both types will occur due to the random nature of the pulse repetition rate. However, since measurements are based on the largest repeatedly occurring PD magnitude, usually only the additive superposition errors will be measured NOTE Superposition errors can attain levels of 1 00 % or more depending on the pulse repetition rate and the characteristics of the measuring system. 3.9.5 pulse resolution time T r shortest time interval between two consecutive input pulses of very short duration, of same shape, polarity and charge magnitude for which the peak value of the resulting response will change by not more than 1 0 % of that for a single pulse The pulse resolution time is in general inversely proportional to the bandwidth Δf of the measuring system. It is an indication of the measuring system’s ability to resolve successive PD events. NOTE It is recommended that the pulse resolution time be measured for the whole test circuit, as well as for the measuring system, as superposition errors can be caused by the test object, for example reflections from cable ends. The relevant technical committees should specify the procedure for handling superposition errors and particularly, the allowable tolerances including their signs. 3.9.6 integration error error in apparent charge measurement which occurs when the upper frequency limit of the PD current pulse amplitude-spectrum is lower than • the upper cut-off frequency of a wideband measuring system; or • the mid-band frequency of a narrow-band measuring system. See figure 5.
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