IEEE 644-2019 pdf download

IEEE 644-2019 pdf download.IEEE Standard for Measurement of Power Frequency Electric and Magnetic Fie lds from ACPower Lines.
3. Electric field strength meters
3.1 General characteristics
Three types of meters used to measure the electric field strength from ac power lines are described in technical literature.
Free-body meter: Measures the steady-state induced current or charge oscillating between two halves of an isolated conductive body in an electric field (see Adler [BI] and Bracken [B2]).
Ground-reference-type meter: Measures the current-to-ground from a flat probe introduced into an electric field (see Miller [8211).
Electro-optic field meter: Measures changes in the transmission of light through a fiber or crystal due to the influence of the electric field (see Cooke [B4j and Harnasaki [B 1 1]).
The free-body meter is suitable for survcytype measurements because it is portable, allows measurements above the ground plane, and does not require a known ground reference. Therefore, this type of meter is recommended for outdoor measurements near power lines.
This standard presents measurement techniques for only the free-body type meter. Flat groimd-referencetype meters can be used only under special conditions described in 5.2. Electric field strength meters intended for characterization of radio-frequency electric fields should not be used to measure the power- frequency electric field strength from ac power lines.
An electric field strength meter consists of two primary parts, the probe and the detector. For commercially available free-body meters, the detector is usually contained in, or is an integral part of, the probe. The probe and detector are introduced into an electric field on an insulating handle. The detector measures the steady-state induced current or charge oscillating between the conducting halves (electrodes) of the probe. The observer is sufficiently removed from the probe to avoid significant perturbation of the electric field at the probe (see 4.1). The size of the probe should be such that charge distributions on the boundary surfaces generating the electric field (energized and ground surfaces) are, at most, weakly perturbed when the probe is introduced for measurement. The electric field should be approximately uniform in the region where the probe will be introduced. Probes can be of any shape; however, meters commercially available in the U.S. are generally in the shape of rectangular boxes, with side dimensions ranging from approximately 7 cm to 20 cm. The meters are calibrated to read the rms value of the power frequency electric field component along the electrical axis (the axis of greatest electric field strength sensitivity).
Free-body meters designed for remote display of the electric field strength also are available. In this case, a portion of the signal processing circuit is contained in the probe and the remainder of the detector is in a separate enclosure with an analog or digital display. A fiber-optic link connects the probe to the display unit. This type of probe is also introduced into an electric field on an insulating handle.
When performing measurements, it is necessary to understand the instrumentation to be able to account for factors such as a dependence on temperature or if the electrical axis of the field strength meter is not coincident with the geometric axis. Other relevant information, is indicated in Figure 1. section C.
The detector, although calibrated to indicate the rrns value of the power frequency field, may, depending on the detector circuit design, measure:
a) A quantity that is proportional to the average value of the rectified power frequency signal from the probe
b) The true rms value of the signal
The response of the detector to harmonic components in the E-tield also depends on the design of the detector circuit. For example, in case a), because of the signal-averaging feature, an analog display will not nccessanly indicate the ntis value of the composite E-field waveform (fundamental plus harmonics) (see Kotter [B19]). For case b), the true rms value of the electric field strength with harmonics could be observed if the detector circuit contained a stage of integration (Misakian [B22]).
The frequency response of the free-body meter can be determined experimentally by injecting a known alternating current at various frequencies and observing the response.
The rated accuracy of the detector at power frequency is a function of the stability of its components at a given temperature and humidity and is generally high (less than 0.5% uncertainty) compared with the reading accuracy when the analog display is read at a distance of 1 m or 2 m.