IEEE 43-2000 pdf free.IEEE Recommended Practice for Testing Insulation Resistance of Rotating Machinery.
IEEE 43 Before any testing is conducted, the winding insulation must be discharged. It is not safe to begin testingbefore the discharge current is zero and there is no discernible return voltage (less than approximately 20 V)after the ground is removed.After completion of the test, the winding should be discharged through a suitable resistor, sized to limit the instantaneous current to 1 A.A minimum discharge time, which is equal tofour times the voltage application duration, is recommended.This time interval is based on the R (resistive),L(inductive), C(geometric capacitive), and absorptive characteristics of the circuit during charging (time ofthe application of the voltage) and discharging (elapsed time since the removal of the voltage source andsubsequent grounding of the winding under test). It is important to remember that the testing is not completeuntil the winding is discharged and there is no discernible voltage. It is recommended that subsequent achigh-potential testing not be conducted until the winding is fully discharged.
During the test period, all appropriate safety measures for the voltages being used must be taken.For testvoltages 5000 V and above, the lead between the test set and the winding must be appropriately insulatedand spaced from ground; otherwise, surface leakage currents and corona loss may introduce errors in the testdata. For safety considerations, and to avoid measuring stray currents, the leads may be shielded.
Restriction of personnel access to the high voltages is mandatory. Use of personal protective equipment isrecommended, as is the use of hot sticks, insulated ladders,etc. If accessible, the phase neutral and line endsof each winding should be connected together during the test to minimize the effect of high-voltage surgereflections that may result from a winding failure.
The safety measures described are by no means exclusive. These are meant only to signify the nature of thehazards involved. It is the responsibility of the users of the test equipment to completely ascertain thepossible hazards involved in the testing, to protect personnel from harm, and to eliminate the risk of damageto the equipment.
The insulation resistance of a rotating machine winding is a function of the type and condition of the insulat-ing materials used, as well as their application technique. In general, the insulation resistance varies propor-tionately with the insulation thickness and inversely with the conductor surface area.IEEE Std 43 pdf download.