The test voltage is connected to the hv terminal and the current is measured at the lv terminal. A fourposition switch selects the test to be made system phase sequence, motor rotation and transformer polarity. Today megger offers the finest line of 5 kv, 10 kv and 15 kv dc insulation resistance testers available anywhere. What is the procedure for testing insulation resistance in. The correct settings, connection procedures, test durations and safety precautions must be implemented to avoid damaging the equipment or possible electrocutions. How to test a threephase motor with a megger hunker. It can give an accurate reading of the measure of resistance and continuity available in a highvoltage circuit and electrical motor. The motor under test must be powered down and disconnected from all equipment and wiring not included in the test. Trending of test data 17 megger baker mtr105 the tests 18. Owing to the nature of the insulation systems used in ht machines such as this, a simple megger test will prove inconclusive. However, ac dielectric tests must supply both reactive and resistive currents to the items under test resulting in larger equipment in size than dc testing devices.
Megger testers and megger test equipment are used by electricians and engineers for testing electrical installations. Megohmmeters meggers are electrical meters used to check the resistance and condition of the motor windings and the condition of the refrigeration and oil environment around the motor windings. I have not personally ever used a megger but from what i understand that type of test would be very time consuming or am i missing something. This is an insulation test of motor windings, commonly referred to as megging, to megger, or to meg a motor. The following sections of the ansineta standard for acceptance testing specifications for.
These conditions result in a decrease in the surfacetosurface contact area with an associated increase in surfacetosurface contact resistance, ultimately causing excessive heating at the junction. Five models are available for general purpose testing which. Electricians motor and generator testing equipment megger. Megger mct1605 test is a lightweight, portable unit for shop and field testing of current transformers using ieee c57. These are the most commonly requested operating manuals from megger programma. In using the megger, a bit of a learning curve is involved. Connect the megger ground lead to the same ground plane the motor is connected to. Understanding insulation resistance testing pdf 0712 technical assistance 800 34391. It is most commonly used in industrial installations with multiphase power supplies.
A spot test should be performed at regular intervals every six months, for ex. The above variables should be controlled as much as possible to promote accurate insulation resistance measurement data. Megger testing insulator electricity electric current. Insulation testing technical guides megger insulation. Curve b shows same values corrected to 20c see page 22, giving a definite downward trend toward an unsafe condition. Megger and bridge test of motor cr4 discussion thread. Protect instrument from any damage because of low external electrical resistance under test. It will calculate the rated knee point in compliance with ieee c57. Insulation resistance testing is a nondestructive test procedure. Troubleshooting with insulation resistance test instruments. Megger is a brand name and not a test description although mostly, the equipment being used for this test is branded megger. Guide to low voltage motor testing test equipment depot. Voltage for testing produced by hand operated megger by rotation of crank in case of hand operated type, a battery is used for electronic tester. Megger operating manuals official distributor for megger.
From power station to plug, megger test equipment helps you maintain the electrical network, monitor its condition and maintain supply to your customers. It is an insulation test to see is the insulation has been injured in any way to cause a short circuit when normal power is applied to. The program allows the user to construct customized application software including data. Weve assembled helpful technical guides on insulation testing from leading manufacturers in the field. Find here insulation testing and continuity, power protection, power transformer testing, power cable infrastructure, cable fault location, general electrical test.
The readings obtained from ir tests on nonshielded. An instructional video on how to megger a motor and the proper use of a megohmmeter. Curve b shows same values corrected to 20c see page. It should always be kept in mind that, technically, this test should always be addresses or called insulation test. With one probe still connected to ground, connect the other test probe to. Megger testing free download as powerpoint presentation. Meggers motor and generator testers ensure the correct phase connection in one of our easytouse testers. A megger is nothing but a giant ohmmeter that creates a very large dc voltage usually 500 volts dc from its internal battery.
Insulation resistance 19 spot or timed insulation resistance test 20 polarisation index pi 21 dielectric absorption ratio dar 22 temperature correction 24 guard terminal 25 three phase test 28 voltmeter28 phase rotation 28 continuity28 diode test 29. The reporting device that is additionally meant to create and render reports in the web will consistently be there to build the reports that you requirement for your framework. The megger technical library provides access to a range of additional content and resources such as technical guides, application notes and more. Avtmttr310 rev b sept 2008 ii software to another person of legal entity provided that you transfer this agreement, the software, including all copies, updates and prior versions, and all documentation to such person or entity, and that you retain no copies, including copies stored on a computer. Figure 1 shows a simplified measuring circuit diagram of the delta 4000 test set measuring a twowinding transformer in ust test mode. Download pdf ieee guide for dielectric frequency response test advancements in industry. Megger guide to electrical insulation testing pdf instrumart. Reverse side of card at right is used to record the test data.
Including megger readings on communications cables. Figure 4typical record of insulation resistance of a mill motor. Connect the megger hot lead to a motor winding lead. We are a uk authorised distributor for new megger testers. The following example shows how to automate the mcsa test using dasylab and the iotech 600 series dsa products. Megger battery test equipment bite2 and bite2p battery impedance test sets n follows ieee 450 recommended practices cell by cell condition evaluation n for specific gravity checksdetermines the condition of leadacid up to 2000 ah and nicad batteries up to 7000ah ncalculations onboard passwarningfail indications n online testing 2 torkel 840860 battery load units. Ac insulation testing may therefore be used in condition monitoring of acpowered apparatus. Meggers range of test equipment will ensure that you have the right instruments to analyse any form of electrical asset, from power station to plug. Threephase dualvoltage motor insulation resistance testing. How to megger a motor also known as an insulation test. Understanding insulation testing anixters engineers provide insight on common testing problems. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs.
A guide to low resistance testing test equipment depot. They have a wide range of electrical test equipment, insulation testers, multifunction testers and test sets. What happens is a dc voltage is applied to the device or winding under test. Meggers new range of dc insulation testers mit515, mit525, mit1025 and mit1525 are targeted at original equipment manufacturers and industrial companies. Curve d indicates a good insulation with an excellent polarization index of 5. This could cause erroneous readings due to heating of the winding typical test currents are 0. Megger testing of residential circuits inspectionnews. Megger invented insulation testing before the beginning of the 20th century and has continued to lead.
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. The complete guide to electrical insulation testing. Absorption curve of test conducted on 350 hp motor. This happens typically when the test current is about 1% of rated current never exceed 10% of rated current. Scribd is the worlds largest social reading and publishing site. A catalogue, for quick reference, of the range of megger test instruments for the maintenance of electrical power systems. Selecting test current range always try to saturate the core. Figure 2typical megger test instrument hookup to measure insulation resistance. Unfollow megger tester to stop getting updates on your ebay feed. The test measures the insulation resistance between the phases andor between phase and ground. To accomplish this, a test procedure should be established and used consistently over time. The goal is to determine if the insulation of a wire has been compromised.
Every electric wire in a facility, whether its in a motor. The three lines leading to the right of the test set are for direct attachment to energized ac power systems up to 600 volts to determine the system phase sequence. As we are an official distributor for megger in ireland, we can source all supporting documentation from the manufacturer if you cant find the operating manual you are looking for in the list below, just contact us directly. I dont like a resistance test only because it misses some issues. Com 99 washington street melrose, ma 02176 phone 7816651400 toll free 18005178431 visit us at. Have anyone hear of a hi megger testing residential circuits as part of their home inspection. Megger testing of instrument cables electric motors.
Figure 3typical scale on the megger insulation tester. Dasylab was chosen as a programming tool because it is iconbased and easily learned and mastered. The issue is covered by ieee standard no43 and is a lengthy and involved subject. How to use a megger to measure and test motor insulation. Megger makes several testers that will check actual insulation resistance. Megger working principle types history uses of megger. Using the megger to test a threephase motor is rather easy, though the safety hazards for this procedure are quite high. You do this by using a high voltage and looking for voltage leaking through the insulation. The meter will read out in megohms millions of ohms. If the result shows that the resistance is under 1 on the meter, after the first 60 seconds, it likely means that the cable has an issue and needs to be removed. To megger test a 3phase motor with a volt megger tester. Electrical test equipment application solutions from megger. High power test and diagnostics combination for medium voltage cables.
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