Measurements of capacitance and internal resistance by the constant current discharge method and the d.c. resistance method, respectively require much (long) measuring time depending on the product ratings provided that the measuring conditions are standardized with specificity of these measuring methods; therefore, it was necessary to select efficient measuring conditions. For this reason, the following application classification has been considered, classifying into four measuring conditions.
In the meantime, it has been suggested that the same discharge current condition may be good for capacitance and internal resistance for every application of four methods; however, classification was made in terms of accuracy in measurement. Note that the same measuring conditions may be used for capacitance and internal resistance within the scope of the capacitors that can obviously achieve accurate measurements.
Class 1 (memory backup)
This class is suitable for those capacitors which are mainly used for RAM memory backup with discharge current units ranging from nA to μA. The characteristics of the capacitors for this application have relatively low capacitance and high internal resistance.
Class 2(energy storage)
This class is suitable for those capacitors which are mainly used for driving motors, requiring power with discharge current units ranging from mA to A. The characteristics of the capacitors for this application have relatively high capacitance and low internal resistance.
Class 3(for power)
This class is suitable for those energy storage capacitors which mainly require a long time operation, requiring the discharge current units ranging from mA to A. e.g. supercapacitors for energy storage.The capacitors for this application have high capacitance in characteristics without any consideration of internal resistance. This class handles higher internal resistance compared with the power application in the class 2.
Class 4(instantaneous power)
This call is suitable for the application that requires instantaneous power (relatively large current) even with a short operating time. The capacitors for this application have low capacitance and low internal resistance in characteristics.
Unless otherwise specified in the individual standards, it is recommended that the measurement items for electric performance by the above class classification shall be selected from those classes shown in Table A.1 according to the usage.
(4.5.1/4.5.2/4.6.1/4.6.2/4.7/4.8 are from International IEC 62391-1)
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