IEC 61000-4-33-2005 pdf – Electromagnetic compatibility (EMC) – Part 4-33: Testing and measurement techniques – Measurement methods for high-power transient parameters.
3 Terms and definitions For the purposes of this part of IEC 61000, the following terms and definitions, together with those in IEC 60050-161 apply. 3.1 electrically small refers to the size of an object relative to the wavelength of the electromagnetic field. When the object is much smaller than the wavelength, it is said to be electrically small 3.2 equivalent area an intrinsic parameter of a magnetic flux sensor (loop) that relates the open circuit voltage of the sensor to the time rate of change of the magnetic flux density linking the sensor 3.3 equivalent height an intrinsic parameter of an electric field (dipole) sensor, which relates the measured voltage across the terminals of the sensor to the E-field component exciting the sensor 3.4 free-field sensor an electromagnetic field sensor used at a location distant from any scattering body or ground plane 3.5 high power electromagnetic HPEM the general area or technology involved in producing intense electromagnetic radiated fields or conducted voltages and currents which have the capability to damage or upset electronic systems. Generally these disturbances exceed those produced under normal conditions (e.g. 100 V/m) 3.6 measurement chain one or more electrical devices connected together for the purpose of measuring and recording an electromagnetic signal 3.7 Nyquist frequency the Nyquist frequency is the bandwidth of a sampled signal, and is equal to half the sampling frequency of that signal. If the sampled signal represents a continuous spectral range starting at 0 Hz (which is the most common case for speech recordings), the Nyquist frequency is the highest frequency that the sampled signal can unambiguously represent
3.8 pre-pulse refers to a portion of an impulse-like transient waveform that occurs at a time before the time of the primary peak 3.9 sensor a transducer that senses a particular electromagnetic quantity (such as an electric or magnetic field, a current or a charge) and converts it into a voltage or current that can be measured. Typically, this is the first element in a measurement chain for EM measurements 3.10 waveform norm a parameter that is determined from a mathematically well-defined operation on a waveform or signal (such as an integration of the waveform), which yields a scalar number that permits a comparison of various waveforms or their effects 3.11 waveform parameter(s) a single parameter that denotes a waveform characteristic (such as the rise time of the waveform), which is difficult to cast into the waveform norm formalism, yet which is useful in describing a response 3.12 –dot a suffix (as in I-dot), which denotes the derivative with respect to time of the quantity (I), implying that the measurement is proportional to the time rate of rise of the response (I) 4 Measurement of high-power transient responses This standard is concerned with the measurement and description of high-power transient signals resulting from a high altitude nuclear detonation (referred to as the high altitude electromagnetic pulse – HEMP) or from the use of a transient source (or pulser) producing high-power electromagnetic (HPEM) fields. Typically, the physical quantities being measured include the electric (E) and magnetic (H) fields in (or near) a facility or test object, or the induced current and charge (or voltage) on conducting wires entering into the facility or test object. This clause of the standard describes the overall measurement techniques for these transient responses, and in Annex A, suggests several waveform parameters and norms that shall be used to characterize the measured responses.
4.1 Overall measurement concepts and requirements The measurement of transient response quantities is realized by using a number of transient signal processing elements linked together in a sequential manner. Referred to as a “measurement chain”, this collection of equipment will detect, process, transmit and record measured transient responses, so that they can be used after the test is finished to analyse a measured quantity or the electrical behaviour of the system under test. Figure 1 shows two typical instrumentation chains that shall be used for measuring high- power transient responses. The measurement chain shown in Figure 1(a) contains the following elements.