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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The geometric capacitance current I C usually does not affect the measurements, because it disappears by the time the first reading is taken at 1 min. It is recommended that subsequent ac high-potential testing not be conducted until the winding is fully discharged.

The absorption current I A or polarization current decays at a decreasing rate. The voltage application time is usually 1 espol IR 1 or 10 min IR 10however, other values can be used. A reversible current of comparatively high magnitude and short duration, which decays exponentially with time of 443-2000 application, and which depends on the internal resistance of the measuring instrument and the geometric capacitance of the winding.

Poluicao em Isoladores Artigos sobre Poluicao em Isoladores. Clause 1 and Clause A current that is constant in time, that passes through the bulk insulation from the grounded surface to the high-voltage conductor, and that depends on the type of bonding material used in the insulation system.

What’s new in the IEEE 43 insulation resistance testing standard? | EASA

Use of personal protective equipment is recommended, as is the use of hot sticksinsulated ladders, etc. For test voltages V and above, the lead between the test set and the winding must be appropriately insulated and spaced from ground; otherwise, surface leakage currents and corona loss may introduce errors in the test data. Comparing the change in insulation resistance or total current with the duration of the test voltage application may be useful in appraising the cleanliness and dryness of a winding.

If times t 2 and t 1 are not specified, they are assumed to be 10 min and 1 min, respectively.

The insulation espoal of a rotating machine winding is a function of the type and condition of the insulating materials used, as well as their application technique. In general, the insulation resistance varies proportionately with the insulation thickness and inversely with the conductor surface area.


After the applied direct voltage is removed, a suitable discharge circuit should be provided see Clause 4. It may be plotted on a log-log graph as a straight line. Guidelines for test voltages are presented in Table 1. L inductiveC geometric capacitiveand absorptive characteristics of the circuit during charging time eapaol the application of the voltage and discharging elapsed time since the keee of the voltage source and subsequent grounding of the winding under test.

The safety measures described are by no means exclusive.

This time interval is based on the R resistive. 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. The conduction current I G in well-bonded polyester and epoxy-mica insulation systems is essentially zero unless the insulation has become saturated with moisture.

Readings of insulation resistance are taken after the test direct voltage has been applied for 1 min.

What’s new in the IEEE 43 insulation resistance testing standard?

It is not safe to begin testing before the discharge current is zero and there is no discernible return voltage less than approximately 20 V after the ground is removed. The magnitude of the surface leakage current is dependent upon temperature and the amount of conductive material, i. The effect is more pronounced if the surface is also contaminated, or if cracks in the insulation are present.

A high surface leakage current, i.

43-2000 Resistencia de isolação

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. After completion of the test, the winding should be discharged through a suitable resistor, sized to limit the instantaneous current to 1 A. 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.

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. These electrons and ions drift until they become trapped at the mica surfaces commonly found in rotating machine insulation systems.


K is a function of the particular insulation system and applied test voltage, t is time of applied direct voltage, n is a function of the particular insulation system. Before any testing is conducted, the winding insulation must be discharged. Since these molecules have to strain against the attractive forces of other molecules, it usually takes several minutes after application of the electric field for the molecules to become reoriented, and, thus, for the current-supplied polarizing energy to be reduced to almost zero.

Note that the effects of moisture contamination on a healthy winding should not preclude obtaining acceptable readings. Dust or salts on insulation surfaces, which are ordinarily nonconductive when dry, may become partially conductive when exposed to moisture or oil, and, thus, can lower the insulation resistance. This does not imply that more modern insulation materials are better because the absorption current is lower and the resulting insulating resistance is higher.

The total resultant current I T is the sum of four differ- ent currents: The measured insulation resistance will usually rapidly increase when the voltage is first applied, and then gradually approach a relatively constant value as time elapses see Figure 4.

Regardless of the cleanliness of the winding surface, if the winding temperature is at or below the dew point of the ambient air, a film of moisture may form on the insulation surface, which can lower the insulation resistance or polarization index. For example, polyethylene has essentially no absorption current, yet because of its thermal limitations, it would be completely unsuitable for application 43-20000 most rotating machines.

Figure 1—Equivalent circuit showing the four currents monitored during an insulation resistance test. The measurement of insulation resistance constitutes a direct-voltage test and must be restricted to a value espall to the voltage rating of the winding and the basic insulation condition.

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 43-200 body in insulated rotor windings.