Either condition could indicate insulation failure, poor insulation, andor improper test connections. Insulation resistance testing introduction insulation resistance testers can be used to determine the integrity of windings or cables in motors, transformers, switchgear, and electrical installations. This current usually at an applied voltage of 500 volts or more is measured by the ohmmeter, which has an indicating scale. The test method is determined by the type of equipment being tested and the reason for testing. As your insulation starts to age and is exposed to environmental hazards such as extreme temperatures, humidity, and chemical compounds, you may experience unexpected deterioration. Threephase dualvoltage motor insulation resistance testing. At c, the fault has been repaired rewinding of the motor so the insulation resistance has returned to. Insulation resistance testing, measuring, monitoring. Insulation resistance testing basics plant services. Direct readings are available from digital meters and on some testers like the megger mto series, two measurement channels are available allowing two resistance measurements at the same time. Insulation resistance testing should be done by qualified personnel, familiar with both insulation resistance testing and with the safe operation of the test equipment. Insulation resistance is measured typically on the surface of a pcb, whereas the internal pcb layers have not been extensively investigated.
How is ir testing done, in view of the fact that at least 80% of electrical maintenance and testing involves evaluating insulation integrity. The et600 is a multifunction megohmmeter capable of producing 125v, 250v, 500v, and v test voltages for insulation resistance measurements up to 4000m also tests acdc voltages up to v with automatic ranging true rms technology. Its multiple test voltages make it the ideal tool for many troubleshooting, commissioning, and preventative maintenance applications. In an industrial facility, the recommended procedure is to perform periodic tests and record the results so damaging trends can be detected and corrected to. Monitor the insulation resistance during the test to ensure that reading is not linear and does not increase exponentially as the test voltage increases.
I n particular, the question was whether the hipot test and the insulation resistance test could be combined into a single measurement. Timeresistance testing method this method is fairly independent of temperature and often. Understanding insulation resistance testing pdf 0712 technical assistance 800 34391. Also, acceptable values of insulation resistance depend upon the equipment youre testing. Fluke 1507 insulation resistance tester the fluke 1507 is a versatile, compact, handheld insulation tester for advanced industrial and electrical insulation testing. Standard for acceptance testing specifications for. Insulation resistance failure of an electric motor is one of the first signs that the motor is about to fail. Insulation resistance testing of low voltage cables in the field. For good insulation, the resistance usually reads in the megohm range. Whichever test you choose, we recommend you measure resistance both phasetophase and phasetoframe if possible. Testing potential transformers relay testing training for.
Megger mit1020 10kv insulation resistance testers are all. A 1954 diacam2 equipped with a 160 x 120 detector and a 38x28 wideangle lens, the c. Troubleshooting with insulation resistance test instruments. At a, the insulation resistance decreases due to aging and dust accumulation.
Insulation resistance testing test equipment depot. Mar 23, 2000 ieee recommended practice for testing insulation resistance of rotating machinery abstract. Portable measurement equipment in a wide variety of fields. Testing insulation resistance of rotating machines, and other recognized organizations. Insulation resistance tester et600 klein tools for. Insulation resistance test values for electrical distribution. Today megger offers the finest line of 5 kv, 10 kv and 15 kv dc insulation resistance testers available anywhere. Insulation resistance testing applications and how they apply to your testing needs consider the equipment to be tested, test voltage requirements, the testing environment, other possible uses, the experience level of those using the tester and measurement safety features of the insulation resistance tester. Insulation resistance testing applications and how they apply to your testing needs consider the equipment to be tested, test voltage requirements, the testing environment, other possible uses, the experience level of those using the tester and measurement safety. In its most basic form, an insulation resistance test is done with a handcrank meter that measures megohms. It is also has more types of currents than some users realize. Time resistance testing method this method is fairly independent of temperature and often.
Consult the insulation resistance test equipment manual or manufacturer for insulation resistance testing procedures and recommended safety guidelines. Recently, there was a discussion in the ieee email safety forum about the relationship between the hipot test current, leakage current, and insulation resistance. Most can be classified as spot reading shorttime tests, time resistance tests, or step voltage tests. Therefore a novel test method was developed to characterize insulation resistance insitu as a function of environmental testing. The dc voltage tests procedures for the measurement of the insulation resistance and polarization index of insulated stator, and rotor windings and how to interpret the results are described in this recommended practice. Jul 06, 2016 insulation testing the insulation resistance tester or megohmmeter, generally known by its trade name megger, can provide critical information regarding the condition of motor insulation. Historically, many field electricians use the somewhat arbitrary standard of 1 megohm per kv. Insulation resistance testing is carried out by applying a constant voltage to the equipment under test while measuring the flowing current. The insulation resistance test is the second test required by the electrical safety testing standards. Insulation resistance testing methods there are several types of insulation resistance test in use today.
Insulation resistance testing of low voltage cables in the. The megger technical library provides access to a range of additional content and resources such as technical guides, application notes and more. Insulation resistance test values use these values in the absence of consensus standards dealing with insulation resistance tests. Learn how insulation resistance test is done developed early in the 20th century, the insulation resistance ir test is the oldest and most widely used test for assessing the quality of insulation. The purpose of this recommended practice is to a define insulation resistance and polarization index testing of the winding of a rotating machine. The test method is determined by the type of equipment being tested and the reason for test ing. Second, the range of a megohmmeter is in megohms, as its name implies, instead of ohms as in a multimeter. Section 7 of the ansineta standard for acceptance testing specifications for electrical power equipment and systems may be reproduced and used on a cut and paste basis for the particular type of equipment to be tested. For basic electrical insulation testing, choose the compact.
Standard for acceptance testing specifications for electrical. Pdf insulation resistance testing of low voltage cables. The generator can be handcranked or lineoperated to develop a high dc voltage which causes a small current through and over surfaces of the insulation being tested fig. The sharp fall at b indicates there was an insulation fault. Oct 31, 2017 recently, there was a discussion in the ieee email safety forum about the relationship between the hipot test current, leakage current, and insulation resistance. Ieee recommended practice for testing insulation resistance. Testing potential transformers relay testing training. Standard test methods for dc resistance or conductance of. Testing of high voltage cables manual horizon power. Convenient lock function and builtin stand for hands free operation. With over 60% of equipment failures being ascribed to insulation breakdown, it is a key area to monitor. See the site fixed equipment for measurement and testing of electrical networks, energy management and optimization systems. The test measures the insulation resistance between the phases andor between phase and ground.
Test results are dependent on the temperature of the insulating material and the humidity of the surrounding environment at the time of the test. Ieee recommended practice for testing insulation resistance of electric machinery abstract. The following sections of the ansineta standard for acceptance testing specifications for. Insulation resistance test insulation tester electrom. Most can be classified as spot reading shorttime tests, timeresistance tests, or step voltage tests. The megger insulation tester is essentially a highrange resistance meter ohmmeter with a builtin directcurrent generator.
And its reasonable price makes it an excellent value. Figure 2 typical megger test instrument hookup to measure insulation resistance. The megger insulation tester is a small, portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and. The insulation resistance test is an electrical test which uses a certain type and level of voltage 500v d. The insulation resistance of the internal as well as the. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. Its full feature set offers the ability to easily and quickly perform advanced insulation resistance testing.
As a production test, this test is often used as a customer acceptance test, with minimum insulation resistance per unit length often specified by the customer. Recommended test voltages for routine maintenance insulation resistance tests of equipment rated to 4,160v and above. The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables. Insulation resistance testing is performed when troubleshooting electric motors and related equipment.
Ieee standard 432000, recommended practice for testing insulation resistance of rotating machines, recommends the insulation test voltage to apply, based on winding rating, and minimum acceptable values for electric motor windings. This document describes the recommended procedure for measuring insulation resistance of armature and field windings in rotating machines rated 1 hp, 750 w or greater. Whether it involves the connection cables, the sectioning and protection equipment, or the motors and generators, the electrical conductors. Understanding insulation resistance testing pdf 0206 rev. Testing measuring monitoring the insulation resistance is particularly important for the prevention of damage and injury, and for the reliability of electrical systems and equipment. The graph below shows an example of the insulation resistance readings on an electric motor.
To avoid dangerous electrical hazards, we offer insulation resistance testing in our certified labs. How to test three phase ac motors learning electrical. Insulation resistance testing, measuring, monitoring insulation resistance. Insulation resistance of dielectric materials under. Record the insulation resistance, temperature, humidity, and equipment designation. Insulation resistance ir is among the most common motor test. A 1954 camera is ideal for all applications in the building, electrical maintenance and mechanical maintenance sectors. Mar 06, 2014 ieee recommended practice for testing insulation resistance of electric machinery abstract. As it ages, its insulating performance deteriorates. Insulation resistance testing is a nondestructive test procedure. The complete guide to electrical insulation testing. Insulation resistance test of transformer is one of the most important transformer tests we can perform this test at factory or site this test can be classified under type test, routine test, precommissioning and commissioning tests, periodic maintenance transformer tests you can know more about transformer testing and its. For a three phase motor, insulation resistance is usually measured between each motor winding or phase and between each motor phase and motor frame earth using an insulation tester or megger. Pdf insulation resistance testing of low voltage cables in.