Motors are susceptible to the gradual failure of their insulation resistance. Standard for acceptance testing specifications for. Megger has been working hard to make the best electrical test and measurement products for over 100 years. To megger test a dc motor, you might need more than a simple ohmmeter because the problem you are investigating may not become clear until the motor is in operation. A senior tech once told me the megger guard terminal is the same potential as the negative terminal. The remote control function allows for oltc testing.
Motor electrical insulation testing travelers insurance. In addition to their famous insulation testers, they offer 30 distinct product groups with over 1,000 specific products. The motor and phase rotation tester permits the electrical contractor or industrial maintenance electrician to permanently connect and tape the terminals of the motor being installed, without having to first energize the motor by a temporary hookup from a power source, if. The complete guide to electrical insulation testing. From power station to plug, megger test equipment helps you maintain the electrical network, monitor its condition and maintain supply to your customers. Megger invented insulation testing before the beginning of the 20th century and has continued to lead the market in. Connect this spike to the instrument terminal c2 h. Due to heat, vibration, and limited space, the insulation on motor windings is the weak link. Except for ceramics and glass, all insulation materials suffer deterioration over time from normal heat of operation. The megger insulation tester is essentially a highrange resistance meter ohmmeter with a builtin directcurrent generator.
The preferred location for megger testing is at the motor terminals in the marflex electrical cabinets. In this video you will find out how to test 3phase induction motor. Threephase dualvoltage motors are used for most daytoday operations in todays industrial plants. How does one interpret the results of the megger test. Set the voltage setting of the insulation resistance tester to 500v. Press the remote control button to store the result for the tap step. 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. Delivered in onsite case with 1 operating manual, 2 elbowedstraight pvc leads 1. Connect the megger hot lead to a motor winding lead. Megger test procedure manufactured goods electromagnetism.
Direct current highvoltage testing, which measures the current flow through the insulation at 5000 volts and above. Highvoltage dc testing versus medium voltage testing there are two common methods of testing insulation on highvoltage equipment. The instrument should be examined for damage received in transit. Megger test equipment products on sale at tequipment. Be sure to read and understand the safety notice statements in this manual. Full compliance with this standard can be attained with just one tester, the mit10202. Place one megger probe to the any mounting bolt on the breaker box to test for grounding continuity, then touch the other probe to a motor terminal. A guide to diagnostic insulation testing above 1 kv. If any damage is found, file a claim with the carrier at once and notify megger or its nearest representative giving a detailed description of the damages observed. Do not, however, use this standard to reduce any of the precautions given in this. Enclosed in a tough case it is both smaller and lighter than its predecessor making it even easier to carry and store. A viable solution is to megger test with highvoltage test equipment using 1,000 10,000. Offering cat iv, the mit525 is compact, light 5 kv insulation resistance tester for the diagnostic testing and maintenance of high voltage electrical equipment.
How to use a megger to measure and test motor insulation. Understanding insulation resistance testing pdf 0712 technical assistance 800 34391. Iec 6003421 is a welcome development and it is hoped that this guidance document can. Megger testing procedures ieee electrical code issues. The universal testing standard for rotational equipment, ieee 432000, increased the test voltage recommendation to 10 kv for equipment rated 12 kv and above. Well learn how to identify windings, check windings resistance and insulation resistance. Pd testing on switchgear aisgisgil water leak detection and monitoring. The following is a summary of insulation resistance ir testing commonly referred to as megger testing of low voltage cables rated less than 5 kv, recognized by nexans.
When it comes to checking out electric motors, there are special measuring instruments that may be used to detect and diagnose malfunctions. A megger is an ohmmeter that measures resistance in the megohm scale. If a fraction of current flows, it can be measured by these highly sensitive meters. Megger, norristown, pa 19403 of any shortage of materials. For good insulation, the resistance usually reads in the megohm range. One of the sctm working conditions is related to motor. Insulation resistance testing is a nondestructive test procedure. Electrical test equipment power station to plug megger. Ieee standards documents are developed within the ieee societies and the. We are testing the motors insulation, more specifically between the motor windings and the motor casing. Compliance check testing for the regulation of minimum energy performance standards meps is almost always performed on brand new off the shelf motors. Note that the megger can check for faults to the motor iron, but not short. Connect the megger ground lead to the same ground plane the motor is connected to.
Megger guide to electrical insulation testing pdf instrumart. The insulation resistance tester, generally known by its trade name megger, is capable of providing critical information regarding the condition of motor insulation. The megger insulation tester is a small, portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. Threephase power, introduced by inventor nikoa tesla, uses a polyphase system of alternating current to supply power to large motors and motor control systems. Megger testing of instrument cables electric motors. Megger strongly recommends the general safety practices contained in ieee std. Testing methods based on the influence of the test. Megger considers this an excellent safety practice. This document will focus only on the tests that are of importance for field installers which are described as installation and maintenance tests. These products provide testing solutions in critical maintenance areas including cable fault locating, protective.
Isbn 07389785 ss95211 no part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. I cover the different test methods, an analogy on how insulation testing works, safety and the use of insulation test equipment. Mit525 5 kv diagnostic insulation resistance tester megger. Mn434 11 section 1 general information overview this manual contains general procedures that apply to baldor motor products. A megger is used to verify the integrity of the insulation for safety reasons. Megger testing procedures megger testing procedures. These motors run conveyor belts, pumps, fans, and many other applications. The test measures the insulation resistance between the phases andor between phase and ground.
Hi, ive been asked to find an ieee or equivalent test procedure for meggering from the tleads in an mcc cubicle to the motor in the field. 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. Insulation resistance testing of low voltage cables in the. Im not sure if this holds true with modern test equipment, but i think this should be taken into consideration when guarding equipment that could be damaged by a high test voltage, such as a low voltage transformer winding. Whether it involves the connection cables, the sectioning and protection equipment, or the motors and generators, the electrical conductors are insulated using materials with high electrical.
Operation general testing procedure can be altered to achieve optimum conditions for the it is advisable that the battery of the d e t 2 2 is fully test. It uses less conductor material for power transmission than other methods while also providing a constant stream of power. How to megger a motor also known as an insulation test. Condition monitoring visual oil analysismegger test marflex. This is important, because the highvoltage current in threephase. It is both smaller and lighter than its predecessor, making it even easier to carry and store. How to test three phase ac motors learning electrical. Ieee std 1122004, ieee standard test procedure for.
Megger safety precautions when you use a megger, you could be injured or damage equipment you are working on if the following minimum safety precautions are not observed. A guide to diagnostic insulation testing above 1 kv 5. Insulation resistance testing guide chauvin arnoux. Ieee std 1122004 revision of ieee std 1121996 ieee standard test procedure for polyphase induction motors and generators sponsor electric. How to test a threephase motor with a megger hunker. Timeresistance testing method this method is fairly independent of temperature and often. Offering cat iv, the mit1025 is compact, light 10 kv insulation resistance tester for the diagnostic testing and maintenance of high voltage electrical equipment. It is checked by touching the free ends of the leads together while the megger button is pressed on to check for zero. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. It can give an accurate reading of the measure of resistance and continuity available in a highvoltage circuit and electrical motor. This is an insulation test of motor windings, commonly referred to as megging, to megger, or to meg a motor. What is the procedure for testing insulation resistance in. Start the test by pushing the test button and wait until resistance values are stable.
To test a cable with a megger, you connect one probe to the outside of the cable and, with the power turned off, you touch the probe to the conducting wire at the point of connection. A megger is able to measure highvoltage resistance values. Ieee std 432000 recommends a procedure for measuring insulation resistance of armature and field windings in. This is due to easy access and megger test results. Use meggers on highresistance measurements only such as insulation measurements. With one touch oltc from the ttru3, anyone can configure and test all. Rpm insulation systems evaluation and maintenance guidelines.
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. Megger makes electrical test equipment to help you install, improve efficiency and extend the life of assets and cable networks at high, medium and low voltage. Bm12, mj10 mutlivoltage analogue insulation and continuity. Threephase dualvoltage motor insulation resistance testing threephase dualvoltage motors are used for most daytoday operations in todays industrial plants. Insert the current test spike into the ground 30 to 50 metres away from the earth electrode to to be tested. Electricians motor and generator testing equipment megger. Weve assembled helpful technical guides on insulation testing from leading manufacturers in the field. Five models are available for general purpose testing which. The leads used for connecting megger testing with the circuit should be fault free and the two connecting leads should have electrical continuity. Threephase dualvoltage motor insulation resistance testing. Completing turns ratio tests on all transformer taps can be a cumbersome process. The first neta acceptance testing specifications for electrical power equipment and systems was produced in 1972. Be sure to follow good safety measures to prevent electrical shock. Meggers motor and generator testers ensure the correct phase connection in one of our easytouse testers.
The megger technical library provides access to a range of additional content and resources such as technical guides, application notes and more. Step 3 crank the handle for about a minute, and notice the resistance reading. Ieee std 1122004, ieee standard test procedure for polyphase. Pdf in part 1 have been presented some tests as insulation resistance. Insulation testing technical guides megger insulation. Upon completion of this project, the neta technical committee began work on a maintenance document, and maintenance testing specifications for electrical power equipment and systems was published in 1975. Electrical motors cable splices bus bar joints welding joints etc. Using the megger to test a threephase motor is rather easy, though the safety hazards for this procedure are quite high. For your protection, do not install, operate or attempt to perform. Most electrical associations recommend this procedure.
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