Baixe grátis o arquivo Resistencia de enviado por Douglas no curso de Engenharia Elétrica na UniFOA. Sobre: Norma IEEE This resource is available in Spanish It has changed from “IEEE Recommended Practice for Testing Insulation Resistance of Rotating Machinery” to. Buy IEEE RECOMMENDED PRACTICE FOR TESTING INSULATION RESISTANCE OF ELECTRIC MACHINERY from SAI Global.
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Parte 2 de 5 3. The voltage application time is usually 1 min IR 1 or 10 min IR 10however, other values can be used.
This time interval is based on the R resistive. There 43-2000 also be. The absorption current I A or polarization current decays at a decreasing rate. 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.
These are meant only to signify the nature of the hazards involved. Insulation espzol testing involves the application of high direct voltages to machine windings.
It is the responsibility of the users of the test equipment to completely ascertain the possible hazards involved in the testing, to protect personnel from harm, and to eliminate the risk of damage to the equipment.
Resistencia de isolação – Norma IEEE
Comparing the change in insulation resistance or total current 43-2000 the duration 43–2000 the test voltage application may be useful in appraising the cleanliness and dryness of a winding.
The effect is more pronounced if the surface is also contaminated, or if cracks in the insulation are present. To provide greater accuracy around the 1 min point and to allow the data to be plotted on log paper, it is also common to take readings at other intervals such as 15 s, 30 s, 45 s, 1 min, 1.
This decay may take more than 30 min depending on the insulation 43-22000 and machine size of the test specimen. The measurement of insulation resistance constitutes a direct-voltage test and must be restricted to a value appropriate to the voltage rating of the winding and the basic insulation condition.
This time interval is based on the R resistiveL inductiveC geometric capacitiveand 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. Insulation resistance—general theory 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.
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 instrument and the geometric capacitance of the winding. Figure 1—Equivalent circuit showing the four currents monitored during an insulation resistance test. A second component of the absorption current is due to the gradual drift of electrons and ions through most organic materials.
These windings have capacitive and inductive properties that can lead to hazards that may not be readily apparent. It is recommended that subsequent ac high-potential testing not be conducted until the winding is fully discharged. Use of personal protective equipment is recommended, as is the use of hot sticksinsulated ladders, etc.
After the applied direct voltage is removed, a suitable discharge circuit should be provided see Clause 4.
What’s new in the IEEE 43 insulation resistance testing standard? | EASA
In general, the insulation resistance varies proportionately with the insulation thickness and inversely with iere conductor surface area. After completion of the test, the winding should be discharged through a suitable resistor, sized to limit the instantaneous current to 1 A. C, and taken at a specified time t from start of voltage application. Negative polarity is preferred to accommodate the phenomenon of electroendosmosis. For safety considerations, and to avoid measuring stray currents, the leads may be shielded.
The quotient of the insulation resistance at time t 2 divided by the insulation resistance at time espapl 1. The first component is due to the polarization of the impregnating materials because the organic molecules, such as epoxy, polyester, and asphalt, tend to change orientation in the presence of a direct electric field.
The absorption current has two components. The measured insulation resistance will ieeee rapidly increase when the voltage is first applied, and then gradually approach a relatively constant value as time elapses see Figure 4.
What’s new in the IEEE 43 insulation resistance testing standard?
A current that is constant with time, and which usually exists over the sur- face of the end-turns of the stator winding or between exposed conductors and the rotor body in insulated rotor windings. It may be plotted on a log-log graph as a straight line.
A high surface leakage current, i.