The test icon will appear in the bottom right corner until the test is complete. If any particular phase fails the continuity test, your motor. The procedure of the insulation resistance test are given below first, disconnect all the line and neutral terminals of the transformer. Electricians motor and generator testing equipment megger. The correct settings, connection procedures, test durations and safety precautions must be implemented to avoid damaging the equipment or possible electrocutions. Ieee std 1122004, ieee standard test procedure for polyphase. A megger is able to measure highvoltage resistance values. I have not experienced using a digital insulation resistance ir tester, but i think it. Note that the megger can check for faults to the motor.
Megger test motor windings semiannually jan feb mar apr may jun jul aug sep oct nov dec during idle periods. Very large motors or very long cables may take 30 to 40 minutes before the capacitive and absorption currents are minimized enough to provide proper test results. Deepwell pumps and provisional megger testing of the marflex pump motors prior to. The motor under test must be powered down and disconnected from all equipment and wiring not included in the test. Find here insulation testing and continuity, power protection, power transformer testing, power cable infrastructure, cable fault location, general electrical test. Rotate the end shaft approximately 30 degrees and test the motor again. Dielectric discharge test the dielectric discharge dd test is a diagnostic insulation test that allows aging and deterioration of insulation to be assessed. It is performed as a part of acceptance and maintenance test procedure to determine any problems due to poor design, assembly, handling, overloading, fault conditions or poor maintenance. Megger testing procedures ieee electrical code issues. If a fraction of current flows, it can be measured by these highly sensitive meters. The pat 400 series introduces a new level of convenience and speed to pat testing using onboard test results. A megger is an ohmmeter that measures resistance in the megohm scale. Long term storage procedure large ac motors storage storage requirements for motors that will not be placed in service for at least six months from date of shipment.
Megger guide to electrical insulation testing pdf instrumart. Insulation resistance testing guide chauvin arnoux. You do this by using a high voltage and looking for voltage leaking through the insulation. Improper motor storage will result in seriously reduced reliability and failure. Insulation resistance testing of low voltage cables in the field. Major megger insulation resistance testers description quality is crafted into every major megger insulation tester, with excellent test voltage regulation, direct measurement readout and an external guard terminal to eliminate surface leakage current from the measurement. Insulation materials used in motors are classified by the national electrical.
Background the following is a summary of insulation resistance ir testing commonly referred to as megger testing. In the running configuration, the windings are joined with metal jumpers. Although all of its products are manufactured in the united states and england dallas, texas. If one of the values differs substantially from all the.
This is due to easy access and megger test results. In using the megger, a bit of a learning curve is involved. There is an inherent safety problem in earth resistance testing that requires care and planning by the user of the test set. We are testing the motor s insulation, more specifically between the motor windings and the motor casing. With one touch oltc from the ttru3, anyone can configure and test all. Any voltage larger than this may stress the cable and cause premature failure. The windings are marked with tags u1 and u2, v1 and v2, w1 and w2. Test interphase resistance by disconnecting the leads from each terminal with a flathead screwdriver, then touch any two terminals with the two probes. Many sections are mainly applicable to the lvmv induction motor equipment and many others are applicable to either synchronous or dc motors. Transformer turns ratio ttr is one of the most common test used to assess the condition of the transformers windings and core.
Connect the megger hot lead to a motor winding lead. The device is being used since 1889, popularity raised during 1920s since the long back device is same in its uses and purpose of testing, few real improvements appeared in recent years with its design and quality of tester. 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. Condition monitoring visual oil analysismegger test marflex. Any help would be m megger testing procedures ieee electrical code issues engtips. To accomplish this, a test procedure should be established and used consistently over time. It is most commonly used in industrial installations with multiphase power supplies. According to the national electrical code, all values should be over 25 megohm.
The following sections of the ansineta standard for acceptance testing specifications for. Threephase power, introduced by inventor nikoa tesla, uses a polyphase system of alternating current to supply power to large motors and motor control systems. If you are looking for something specific, dont hesitate to contact us. Megger mit1025 insulation tester mit525 insulation resistance tester whats in the box. A catalogue, for quick reference, of the range of megger test instruments for the maintenance of electrical power systems. Jan 19, 2018 its actually an insualtion resistance test.
It can give an accurate reading of the measure of resistance and continuity available in a highvoltage circuit and electrical motor. The test set panel must be connected to a reliable local. Weve assembled helpful technical guides on insulation testing from leading manufacturers in the field. Enclosed in a tough case it is both smaller and lighter than its predecessor making it even easier to carry and store. Motors are susceptible to the gradual failure of their insulation resistance. These motors are not designed for atmospheric conditions that require explosion proof operation. The megger insulation tester is essentially a highrange resistance meter. The term motor used in this checklist refers to all kinds of motors. Meggers motor and generator testers ensure the correct phase connection in one of our easytouse testers. Set the demand rate in the analyzer setup file to the same.
Connections and turnon connect the test sample to the terminals as shown in figure. In this video you will find out how to test 3phase induction motor. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing. Pat410 perfect for those content to bond test solely at 200 ma, the smallest, lightest of the pat400 series weighs only 2. Megger group limited is a manufacturer of electric test equipment and measuring instruments for electrical power applications.
Persons not directly associated with the work must be kept away from test activities by suitable barriers, barricades or warnings. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. Megger the complete guide to electrical insulation testing. The megger test is a method of testing making use of an insulation tester resistance meter that will help to verify the condition of electrical insulation. These motors run conveyor belts, pumps, fans, and many other applications. A megger is used to verify the integrity of the insulation for safety reasons. We have spoken at various points in this manual about the. Make sure the current connections are clean and tight. Each phase to phase must have a continuity if winding is ok. Ul listed motors must only be serviced by ul approved authorized baldor service centers if these motors are to be returned to a hazardous andor explosive atmosphere. In recognition of the critical significance of such demands, the ieee revised their motor testing standard to.
The contract documents are a single integrated document, and as. Rpm insulation systems evaluation and maintenance guidelines. The possibility exists that a fault in the power system will cause a high current to flow into the ground system while the test. The test voltage is the rated voltage of the cable the linetoline voltage. Ieee 43 recommended practice for testing insulation resistance of rotating. How to megger a motor also known as an insulation test. Mn434 11 section 1 general information overview this manual contains general procedures that apply to baldor motor products.
When motors driving centrifugal loads are replaced, actual motor speed should remain the same higher motor speeds can increase energy use c 2006, success by design voltage most threephase motors operate at 460 volts some motors. Aemc instruments with the circuit supplied at a constant voltage, the total. Figure 4typical record of insulation resistance of a mill motor. Standard for acceptance testing specifications for. Completing turns ratio tests on all transformer taps can be a cumbersome process. Most electrical associations recommend this procedure. The test measures the insulation resistance between the phases andor between phase and ground. For instance, when testing electrical cabling or switchgear lowcapacitance equipment. Full compliance with this standard can be attained with just one tester, the mit10202. Test current adjustment test current indicated on the ammeter should. The complete guide to electrical insulation testing. Figure 3typical scale on the megger insulation tester. If the resistance is higher than the maximum display range, the megger will display the symbol on the left side of the screen. Insulation resistance testing of low voltage cables in the.
Pdf in part 1 have been presented some tests as insulation resistance. How to test a threephase motor with a megger hunker. Jul 06, 2016 the test generally applies between 100 and 5,000 v or more. Furthermore, manufacturers of wire, cable, motors, and so on have continually. A protocol involving voltage level, time duration, intervals between tests and connection methods must be composed, taking into account the type and size of the equipment, its value and role in the production process and other factors. Threephase dualvoltage motor insulation resistance testing threephase dualvoltage motors are used for most daytoday operations in todays industrial plants. 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. Examine the resistance values you have entered in your table. Curve b shows same values corrected to 20c see page 22, giving a definite downward trend toward an unsafe condition. The above variables should be controlled as much as possible to promote accurate insulation resistance measurement data. This is an insulation test of motor windings, commonly referred to as megging, to megger, or to meg a motor.
Motor electrical insulation testing travelers insurance. Continue with this testing procedure until you have values for all the spaces of your table. Understanding insulation resistance testing pdf 0206 rev. To effectively test the motor, you must disconnect the field coils where possible.
Some sections may explain explicitly between the three configurations, but have different requirements for each. How to test three phase ac motors learning electrical. Electrical test equipment power station to plug megger. The minimum and maximum ir insulation resistance values can be found in the megger. This checklist incorporates all range of motors equipment. The term motor used in this checklist refers to all kinds of motors ge produced which are stated in section 4 in this document. Due to heat, vibration, and limited space, the insulation on motor windings is the weak link. Com reference manual applications guide delta 4000 12 kv insulation diagnostic system zmah02e. Connect the megger ground lead to the same ground plane the motor is connected to. Section g recommended test leads megger test leads recommended for use with the 100 ampere range are as follows. How to use a megger to measure and test motor insulation. 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.
Mit525 5 kv diagnostic insulation resistance tester megger. The way the connections are made depends on the type of test being undertaken and details are given in measuring techniques. The megger technical library provides access to a range of additional content and resources such as technical guides, application notes and more. Megger testing is method used to determine the insulation condition of. Ieee standards documents are developed within the ieee societies and the. The test method is determined by the type of equipment being tested and the reason for testing. Section d operating procedure follow the safety precautions of section b measurements on 600o 100ampere dlro range 1. One of the sctm working conditions is related to motor. We are testing the motors insulation, more specifically between the motor windings and the motor casing. Tests for asynchronous motors industry support siemens. 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. Megger working principle types history uses of megger.
Motor slip rated speed is on the motor nameplate caveat. Threephase dualvoltage motor insulation resistance testing. Be sure to read and understand the safety notice statements. Perform this procedure a number of times as most dc motors use a carbon brush and copper commutator to conduct the electrical power to the armature.
Jul 17, 2017 release the push button on the megger or stop the cranking of the meter. Using the megger to test a threephase motor is rather easy, though the safety hazards for this procedure are quite high. Maintenance checklist continued seasonal shutdown checklist when the system is to be shut down for an extended period of time, the following services should be performed. Delivered in onsite case with 1 operating manual, 2 elbowedstraight pvc. If you are testing a newer motor, one whose megger readings are in the gigaohms range, then the ratio between the 1 min and 10 min reading may end up being 1. It uses less conductor material for power transmission than other methods while also providing a constant stream of power. In addition, the elapsed time of the test is displayed constantly removing the need for separate timer. 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 available, to determine motor rotation. Five models are available for general purpose testing which. This prevents testing coiltocoil insulation resistance for all six coils and their combinations. The goal is to determine if the insulation of a wire has been compromised. Insulation resistance testing is a nondestructive test procedure. Test spikes and long test leads are necessary for all types of earth testing and the optional earth testing field.
Insulation testing technical guides megger insulation. It is checked by touching the free ends of the leads together while the megger button is pressed on to check for zero. Step 3 crank the handle for about a minute, and notice the resistance reading. 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. Using a pi test to determine the condition of the motor can be misleading. What is the procedure for testing insulation resistance in. The leads used for connecting megger testing with the circuit should be fault free and the two connecting leads should have electrical continuity. Offering cat iv, the mit1025 is compact, light 10 kv insulation resistance tester for the diagnostic testing and maintenance of high voltage electrical equipment. Reverse side of card at right is used to record the test data. The test voltage selected for this type of test is less than 5 kv, and is applied for up to one minute, or until the measured insulation resistance value stabilizes. How to tell your induction motor is good using digital megger.
Megger test procedure manufactured goods electromagnetism. Three new pat testers with full database functionality based on the well received pat300 series. The international electrical testing association neta was formed in 1972 to establish uniform testing procedures for electrical equipment and apparatus. Well learn how to identify windings, check windings resistance and. From power station to plug, megger test equipment helps you maintain the electrical network, monitor its condition and maintain supply to your customers. 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. Megger testing procedures megger testing procedures. Ieee 112 standard test procedure for polyphase induction motors and. Mit200 instruments offer a range of safety and operation features expected from a. We use a unit 5urg2 digital megger to test induction motors, but i dont.
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