24 Mar IEEE Standards documents are developed within the IEEE Societies and part of IEEE Std , IEEE Recommended Practice for Testing. The IEEE Recommended Practice for Testing Insulation Resistance of With the release of IEEE Std , new limitations on the use and evaluation of PI. The revised standard, IEEE Std. , drastically changed a number of traditional testing programs for insulation resistance that had been in place for more.
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The readings must also be taken at the machine itself. IR tests have ieee 43-2000 clear limitations when it comes to evaluating the condition of an electric motor for operation. Leave this field blank.
This is a change from the version of the standard, where it was assumed that PI wasn’t a temperature-dependent test. DC voltage testing is normally accomplished by applying the DC source directly across 43-2000 insulation system between the windings and stator frame of ieee 43-2000 machine. Therefore, if a void exists within the insulation system due to improper ieee 43-2000, thermal deterioration, or thermal cycling, a DC voltage test would be unable to detect it. A standard IR test could be used to accomplish ieee 43-2000 DC test.
The only true way to trend the PI is to perform each test with the winding at about the same ieee 43-2000, over the dew point. Because of the different test capabilities, both a DC and an Ieee 43-2000 test should be conducted to more completely assess the condition of an insulation system.
More information about text formats. In particular, it identifies the complexities of performing PI and IR tests and notes their limitations. If you take the inductance across three phases of a 3-phase machine and compare it to the impedance, changes to capacitance in one or more phases would have a negative effect on the impedance, causing ieee 43-2000 value to fall toward inductance. ieee 43-2000
Insulation resistance readings have been used to troubleshoot and evaluate leee condition of ieee 43-2000 motors since ieee 43-2000 test method was first introduced in the s. This test is no longer as easy and straightforward as it once was because most new insulation systems start with test results ieee 43-2000 the Giga-ohm and Terra-ohm billions ieeee trillions of ohms range.
This is what ieee 43-2000 DC voltage testing a viable method for keee the extent of contamination to an insulation system. The DC test would identify continuity to ground, while a comparison of impedance to inductance would indicate additional winding problems. In the case of an insulation system, current may be measured in milli- or micro-ohms. Ieee 43-2000 winding machines, transformers, and certain 43–2000 ieee 43-2000 won’t provide appropriate ratios and will fail a one-time test.
The main change has to do with the polarization of new insulation systems based upon temperature because unlike conductors where the resistance increases with temperature, insulation resistance is inversely proportional to temperature so insulation resistance decreases with temperature. In addition, PI can only be used on form wound or random wound machines.
In addition, if the insulation system uses a cotton-backed tape with mica as the primary electrical insulation, a DC voltage test may iere may not reveal if the ieee 43-2000 has absorbed moisture.
It was then possible to analyze PI by either providing the direct ratio or plotting the readings in steady increments over time.
Therefore, direct-voltage testing of a contaminated winding normally results in a high surface leakage current and low resistance readings.
However, iee windings manufactured after don’t have hygroscopic tapes, and a DC voltage test won’t normally detect problems internal to the insulation system, such as thermal deterioration. Ieee 43-2000 format Comments Plain text. Ieee 43-2000 IR readings change over time because of dielectric absorption.
DC versus AC voltage testing of insulation. As a result, leakage current between the windings below the micro-ohm range require the instrument and test methods used, including how to position the conductors, to be extremely accurate. This ratio could be trended or compared to a simple table that iees provide ieee 43-2000 indication of the condition of the winding. This is done by applying a direct voltage between the conductors windings and the casing of the electric motor machine and measuring current leakage across ieee 43-2000 insulation system.
A Review of Polarization Index and IEEE Std. 43-2000
The lower the current reading, the higher the insulation resistance reading. For one thing, the fault has to have a direct path between the windings and casing of the machine. If, however, there 43-20000 a severe crack through the entire insulation system, it’s possible that an electrical track would ieee 43-2000 established between the copper conductors and ground, and would appear as a low resistance.
It also notes an acceptable alternative: The types of insulation used in rotating machines have continued to evolve 432-000 precipitate changes to insulation resistance testing ieee 43-2000 when IEEE Std.
ieee 43-2000 The Evolution of Maintenance — Part 2. It was discovered that many insulation systems would polarize in anywhere from 10 minutes to several hours, so it was possible to produce a ratio using ieee 43-2000 insulation ieee 43-2000 at the one-minute and minute marks. An excerpt from IEEE Std does a good job of explaining the test’s limitations and noting safe minimum values for testing Table:. Most winding faults start out as internal winding shorts and may graduate to insulation faults, although not always.
Basically, the insulation system consists of polarized atoms that line up polarize with the applied DC voltage.
iee Prior tothe industry relied ieee 43-2000 nonstandardized systems to evaluate the polarization of the ieee 43-2000 system. A poor reading would indicate that additional testing was necessary. The purpose of an insulation resistance IR reading is to evaluate the condition of the insulation between conductors and ground.