IEEE C62.41.2-2002 pdf download

IEEE C62.41.2-2002 pdf download.IEEE Recommended Practice on Characterization of Surges in Low-Voltage (1000 V and Less) AC Power Circuits
Answers might not exist to all of the questions raised by the considerations listed above. In particular, the answers related to specific equipment sensitivities, both in terms of component failure and especially in terms of processing errors, might not be available to the designer. The goal of the reader might be selection among various SPDs and equipment protected by them. Subsets of the parameters in this section may then apply, and the goal of the reader might then be the testing of various SPDs under identical test conditions. The following can guide the reader in identifying parameters, seeking further facts, or quantifying a test plan:
a) Protection desired. The protection desired can vary greatly depending upon the application. For example, in applications not involving on-line performance, protection might be desired merely to reduce hardware failures by a certain percentage. In other cases, such as data processing, critical medical processes, or manufacturing processes, any interruption or upset of a process is likely to be unacceptable. Hence, the designer should quantify the desired goal with regard to the separate questions of hardware failure and process upset. Another consideration is the need to make an informed decision either to provide protection by and survival of all SPDs for the rare event of a direct lightning flash to the structure of interest or, alternately, to limit such protection for the common occurrence of surges (including remote lightning, but not a direct flash).
b) Equipment sensitivities. Specific equipment sensitivities should be considered in concert with the above-mentioned goals. The sensitivities will be different for hardware failure or process upset. Such definitions might include maximum surge remnant amplitude and duration that can be tolerated downstream of a mitigation device, waveform or energy sensitivity, etc.
c) Power environment—surges. The applicable test waveforms recommended in this document should be quantified on the basis of the location categories and exposure levels defined in this recommended practice, as well as consideration of surges associated with a direct lightning flash to the structure. This latter scenario is mentioned in 7.4, with further information and background presented in Informative Annex A.
d) Power environment—electrical system. The magnitude of the root-mean-square (rms) power-line voltage, including any anticipated variation, should be quantified. Power system voltages are generally regulated to comply with ANSI C84.1-1989 [B2].
2 That standard specifies two ranges (A and B) of service and utilization voltages and explicitly acknowledges the occurrence of abnormal conditions that cause these voltages to be exceeded. Successful application of SPDs requires taking into consideration these occasional abnormal occurrences. Appropriate selection of the limiting voltage, switching voltage, and maximum continuous operating voltage (MCOV) ratings is essential.
e) Performance of SPDs. Evaluation of an SPD should verify a long life in the presence of both the surge and electrical system environments described above. At the same time, the remnant voltage of the SPD should provide a margin from the withstand levels of the equipment in order to achieve the desired level of protection. It is essential to consider all of these parameters concurrently. For example, the use of a protective device rated very close to the nominal system voltage might provide attractive remnant values, but can be unacceptable when a broad range of occasional abnormal deviations in the amplitude of the mains waveform are considered. Durability or overall performance of the SPD should not be sacrificed for the sake of a low remnant. Possible failure mode scenarios need consideration.
f) Test environment. The surge test environment should be carefully engineered with regard to the preceding considerations and any other parameters felt important by the user. A typical test-environment description will include definitions of simultaneous voltages and currents, along with demonstrations of proper short-circuit currents. It is important to recognize that specification of an open-circuit voltage without including simultaneous short-circuit current capability is meaningless. To avoid this pitfall, this recommended practice provides both voltage and current descriptions. Details on test procedures are given in the companion recommended practice IEEE Std C62.45  -2002.
g) Costs. The cost of surge protection can be small, compared to overall system cost and benefits in performance. Therefore, added quality and performance in surge protection may be chosen as a conservative engineering approach to compensate for unknown variables in the other parameters. This approach can provide excellent performance in the best interests of the user, while not significantly affecting overall system cost.IEEE C62.41.2 pdf download.IEEE C62.41.2-2002 pdf download