IEEE C57.113-2010 pdf download
IEEE C57.113-2010 pdf download.IEEE Recommended Practice for Partial Discharge Measurement in Liquid-Filled Power Transformers and Shunt Reactors.
NOTE 1—If the pulse train response differs significantly from those recommended in IEC 60270 the actual dependence of the reading. R, versus the pulse repetition rate. N, should be determined in order to judge the evaluation of the apparent charge level.
NOTE 2—To eliminate stochastically appearing noise pulses at comparatively low repetition rate, for instance one pulse per cycle of the applied ac test voltage, some PD detectors arc equipped with special features for noise suppression which may reject pulses having a repetition rate below 100 lIz. (‘are should be taken when using this instrumentation because PD pulses of high magnitude may not be recognized if they do not ignite in each hall-cycle of the applied ac test voltage. To avoid such erroneous measurements, a visualization of the phase-resolved PD pulses is strongly recommended using a suitable display unit. such as a scope or a computer.
NOTE 3—The specified pulse train response is appropriate only for ac test voltages where the frequency may range between 40 I-li and 400 Hz. For dc test voltages or test voltages composed by ac and dc voltages, it is recommended to evaluate the number versus the magnitude of PD pulses.
4.4.3 Display unit
In addition to the measurement uf the apparent charge level by means of analog or digital meters it is strongly recommended to display the phase-resolved PD paerns by means of a suitable display unit, such as an oscilloscope or a computer. This may assist not only the identification and classification of harmful PD defects but also the discrimination of disturbing electromagnetic interferences, which are often not phase-coffelated.
4.4.4 Basic sensitivity
The basic sensitivi should be determined by means of calibrating pulses specified in 4.6, which are injected into the input of the measuring impedance connected to the PD measuring instrument via the associated measuring cable. A calibrating charge of 50 pC should cause a minimum deflection of 50% of the full reading of the indicating instrument or of the optional display unit.
4.4.5 Linearity
The lineari should be determined by means of ca1i1iting pulses specified in 4.6, which should be injected in the measuring impedance connected via the associated measuring cable to the PD measuring instrument. The measuring sensitivity should be adjusted such that the full reading (100%) is obtained for an injected calibrating charge of 500 pC. After that the magnitude of the calibrating charge should he reduced stcpwise by 100 pC. Under this condition the values indicated b the PD measuring instrument should not deviate 1w more than ±lO% from the true magnitudes of the injected pulse charges.
4.5 PD calibrator
The PD calibrator is intended for the simulation of the charge transfer from the PD source to the terminals of the test
object; see Annex C. To generate artificial PD pulses required for this purpose, the calibrator is generally equipped with a pulse generator connected in series with a calibrating capacitor, see Figure 1. The pulse generator produces fast rising step voltages of known magnitudes, V0. Therefore the calibrating charge is given by Equation (2):
To display the calibrating pulses when the actual PD test under high voltage is mnning, the calibrating capacitor, Cj, which is usually designed only for low voltages, should be substituted by an HV calibrating capacitor, this should be PD-free up the maximum ac test voltage level. The measuring cable between the step pulse generator and the terminating box connected to the input of the HV calibrating capacitor should be matched with the characteristic cable impedance in order to avoid disturbing pulse reflections. Generally the HV calibrating capacitor should be located as close as possible to the HV tenninal of the test object.
