IEEE - The Institute of Electrical and Electronics Engineers@ Inc.
Scope
This test procedure applies to the detection and measurement of partial discharges (corona) occurring in switchgear equipment and/or components during dielectric tests@ where applicable. The following types of equipment are included: high-voltage fuses@ high-voltage switches@ high-voltage circuit breakers@ reclosers and sectionalizers@ and switchgear assemblies. Purpose Partial discharge measurement in switchgear equipment can be made on the basis of measurement of the apparent charge. Relevant measuring systems are classified as narrow-band or wide-band systems. Both systems are recognized and widely used. General principles of partial discharge measurement@ including both broad and narrow-band methods@ are covered in IEEE Std C57.113-1991 and IEC 270 (1981).1 The use of partial discharge testing as a tool to assess the integrity of insulation systems requires a great deal of judgment. It should not be used as a general@ all inclusive test such as the 60 Hz and impulse dielectric tests. Although it may be appropriate to perform a partial discharge test on an entire device for some types of equipment@ practice tends to indicate that it should be used to evaluate component parts of apparatus. If partial discharges on apparatus are associated with self-restoring insulation@ such as air@ and do not affect nearby non-self-restoring insulation materials@ then relatively high levels of partial discharge may be acceptable if the resultant radio influence voltage (RIV) level and the audible discharge noise level is acceptable@ see NEMA 107-1987. It may be necessary to temporarily isolate areas of high partial discharge so that other more critical areas involving non-self-restoring insulations may be more carefully evaluated. Immersing components in oil or SF6 gas is an accepted means of isolating noncritical areas so that critical areas can be tested. Thus@ partial discharge testing is used more effectively to evaluate isolated areas of high dielectric stress that are judged to have the probability of deterioration of their non-self-restoring insulation.1Information on references can be found in clause 3.