A current resulting from molecular polarizing and electron drift, which decays with time of voltage application at a decreasing rate from a comparatively high initial value to nearly zero, and depends on the type and condition of the bonding material used in the insulation system. Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copy- right Clearance Center. During the s, several changes were made to the types of insulation used in electric rotating machines. The effect is more pronounced if the surface is also contaminated, or if cracks in the insulation are present. This time interval is based on the R resistive , L inductive , C geometric capacitive , and absorptive characteristics of the circuit during charging time of the application of the voltage and discharging elapsed time since the removal of the voltage source and subsequent grounding of the winding under test. If the insulation resistance or polarization index is reduced because of contamination, it can usually be restored to an acceptable value by cleaning and drying.
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Published 24 March A second component of the absorption current is due to the gradual drift of electrons and ions through most organic materials.
43-2000 Resistencia de isolação
In general, the insulation resistance varies proportionately with the insulation thickness and inversely with 432-000 conductor surface area. Insulation resistance measurement has been recommended and used for more than half a century to evaluate the condition of electrical insulation. The capability of the electrical insulation of a winding to resist direct cur- rent.
A current that is constant in time, that passes through the bulk insulation from the grounded surface to the high-voltage conductor, ieee 43-2000 that depends on the type of bonding material used in the insulation ieer. The total resultant current I T is the sum ieee 43-2000 four differ- ent currents: If the test voltage is too high, the applied test voltage may over stress the insulation, leading to insulation failure.
The safety measures described are by no means exclusive. It may be plotted on ieeee log-log graph as a straight line. It is important to remember that the testing is not ieee 43-2000 until the winding is discharged and there is no discernible voltage.
Members of the committees serve voluntarily and without compensation. Whereas individual insulation resistance measurements may be of questionable value, the carefully maintained record of periodic measurements, accumulated over months and years of service, is of unquestioned value as a measure of some aspects of the condition of the electrical iese. If the winding is wet or dirty, a low steady value will usually be reached 1 min or 2 min after the test voltage is applied.
This time interval is ieee 43-2000 on the R resistiveL inductiveC geometric capacitiveand absorptive characteristics of the circuit iee charging time of the application ieee 43-2000 the voltage and discharging elapsed time since the removal of the voltage source and subsequent grounding of the winding under test.
After completion of the test, the winding should be discharged through a suitable resistor, sized to limit the instantaneous current to 1 A.
The insulation resistance of a rotating machine winding is a function of the type and condition of the insulating materials used, as well as their application technique. If accessible, the phase neutral and line ends of each winding should be connected together during the test to minimize the effect of high-voltage surge reflections that may result from a winding failure.
Modern types of filmcoated wire, as well as epoxy-mica or polyester-mica insulated stator windings, may approach a constant value of insulation resistance in 4 min or less. The absorption current I A or polarization current decays at a decreasing rate. It is recommended that subsequent ac high-potential testing not be conducted until the winding is fully discharged.
When a document is more than five years old and has not been reaffirmed, it is rea- sonable to conclude that its contents, although still of some value, do not wholly reflect the present state of the art.
Furthermore, the viewpoint expressed at the time a standard is approved and issued is subject to change brought about through ieee 43-2000 ueee ieee 43-2000 state of the art and comments received from users of the standard. A reversible current of comparatively high magnitude and short duration, which decays exponentially with time of voltage application, and which depends on the internal resistance of the measuring iere and the geometric capacitance of the winding.
These are meant only to signify the nature of the hazards involved. C, and taken ieee 43-2000 a specified time t from start of voltage application. The discharge current manifests itself in two components:. For ieee 43-2000 reason, IEEE and the members of its societies and Standards Coordinating Committees are not able to provide an instant response to interpretation requests except in those cases where the matter has previously received formal consideration.
A current resulting from molecular polarizing and electron drift, which decays with time of voltage application at a decreasing rate from a comparatively high initial value to nearly zero, and depends on the type and condition of the bonding material used in the insulation system.
The quotient of the insulation resistance at time t 2 divided by the insulation resistance at time t 1. For older types of insulation, a reasonably steady value is usually reached in 10—15 min. Insulation resistance tests are usually conducted at constant direct voltages ieee 43-2000 —10 0 V having negative polarity.
Resistencia de isolação – Norma IEEE
Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copy- right Clearance Ieee 43-2000. By definition, the insulation resistance is the quotient of the applied direct voltage across the insulation divided by the total resultant current at a given time. They are not iere members of the Institute.