Megger Safety Precautions While using a megger, you could be injured or damage equipment you are working on if the following MINIMUM safety precautions are not observed. AFAIK it is not to be used on electronic circuits . For the detailed technical specification of them please refer to the respective Data Sheets. A senior tech once told me the Megger guard terminal is the same potential as the negative terminal. Title: Interpreting Megger Readings Created Date: 11/2/2010 2:47:25 PM 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. Setting Chart Limits Power DB. 2 shows a portion of the results; pit depth corrosion and Megger earth tester readings are plotted for points along the pipeline. ... while a bewildering exercise was necessary to correct readings at any other position. … Megger is the name of the company that makes the device. Although all of its products are manufactured in the United States and England (Dallas, Texas; Valley Forge, Pennsylvania; and Dover, England), Megger is an international company with sales and technical offices throughout the world. Simply take successive readings at specific times and note the differences in readings (see curves, Figure 2). 2: Earth resistivity survey of pipeline shows where corrosion is most likely to occur (source: Ref. Fig. 3.) This document will focus only on the tests that are of importance for field installers which are described as “Installation” and “Maintenance” tests. The megger test is checking the condition of the ground wall insulation of the motor. Every electric wire in your plant – whether it’s in a motor, generator, cable, switch, transformer, etc. The corrected reading of 200 megohms from the above example is shown at months" in Figure 2. Please find all available Data Sheets listed below. Megger - The Complete Guide to Electrical Insulation Testing: Our thanks to Megger for allowing us to reprint the following. At initial contact, a low resistance reading will be observed. Megger recommends that the BITE3 be made part of a comprehensive battery maintenance program with readings taken and recorded semi-annually for flooded, lead-acid cells and quarterly for VRLA. • Disconnect cables from equipment on both ends. WHAT IS “Good” insulation? Over time, ground From left to right: Fluke TL165X/UK, Megger 1001-991 (standard leadset supplied with all Megger MFTs), Megger 1001-975 Optional Fused Leads Both ranges are supplied with a remote test probe (with the exception of the Fluke 1651B), making testing easier and quicker, and a mains test lead for testing directly at the socket. When a Megger or a multi meter is connected to take readings, a voltage is actually being supplied. The corrected reading of 200 megohms from the above example is shown at months" in Figure 2. between two contact points. Check for burnt, damage to body or cooling fan or shaft. The recorded readings should be logged and com-pensated for temperature according to the selected baseline temperature. We also check the phase to phase resistance reading and are looking for no more than a 10% difference max. Any reading above 1.25 is considered excellent. 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. Use megger on high-resistance measurements only, such as insulation measurements … • If lugs or accessories are not being used, cutback the cable as described below. In this video you will find out how to test 3-phase induction motor. The ratio of two time-resistance readings (such as a 60-second reading divided by a 30-second reading) is called a dielectric absorption ratio.If the ratio is a 10-minute reading divided by a 1-minute reading, the value is called the polarization index.. – Megger Testing General Inspections For the single phase motor, do the following: (1) Check the appearance of the motor. For example, you may test one piece of equipment three days in […] Contact Us Toll-Free: 800-903-9870 Phone: 800-903-9870 Fax: 440-238-0660 Email: click here The basic ones that I know are , 1000 volt and 500 volt. Low megger readings Low megger readings rockman7892 (Electrical) (OP) 11 Nov 08 13:54. These value are very useful for determining insulation quality. We were taking a megger reading on a motor feeder the other week and found that on two of the phases the reading is indicating 0 megahomes. If some of the windings are shorted or you have bad connections, then the resistance readings … For tests we'll use MEGGER MIT 310. It is actually an insulation tester , but can be used for continuity tests. Today Megger offers the finest line of 5 kV, 10 kV and 15 kV (dc) insulation resistance testers available anywhere. Alternatively, readings can be compared to “like” test specimens. We have recently implemented a megger PM in our plant. How to Interpret Megohmmeter Readings | Hunker. Tests by this method are sometimes referred to as absorption tests. NETA Accredited Companies ANSI/NETA ATS-2009 The following in a lisiting of all NETA Accredited Companies as of the date this document was approved by ANSI as an American National Standard, February 19, 2009. 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. The BITE3 is quick, reliable and easy to use. The insulation resistance test, a.k.a., the “Megger test”, is as relevant as ever and, in many applications, is preferred to other insulation test methods. We supply a broad range of Megger (Programma) instruments. This test is primarily conducted on form wound motors and generators. If you can’t find your desired Data Sheet below please contact us – we’re always happy to help out. Megger recommends that impedance measurements with the BITE2 or BITE2P be made part of a battery maintenance program with readings taken and recorded semiannually for flooded batteries and quarterly for VRLA. Improvements over the years. Megger Group Limited is a manufacturer of electric test equipment and measuring instruments for electrical power applications. What is actually happening is the "charging up" of the effective capacitor. Megohmmeters, also known as insulation testers or “megger testers” measure resistance to determine current leakage and identify faulty insulation. It is practically impossible to determine rules for the actual minimum insulation resistance value of a motor because resistance varies according to method of construction, condition of insulation material used, rated voltage, size and type. Plot the corrected insulation resistance readings for each test on a chart for reference and trending. Hunker.com If the megger reads a resistance under 1 (1,000 ohms) on your meter after the initial 60-second interval, the cable has failed and the cable should be removed. Has anyone ever heard of anything like this? Plot the corrected insulation resistance readings for each test on a chart for reference and trending. Dielectric Absorption Ratio and Polarization Index. • Clean cable ends/lugs with appropriate cleaning solution. – is carefully covered with some form of electrical insulation. These elements include Temperature Resistance 0.99 1.00 20 C° C Wire Coil Strip - Shunt 50 C 350° ° Figure 1: Qualitative Resistance-Temperature Curve for Manganiniii Megger Data Sheets. Introduction: The measurement of insulation resistance is a common routine test performed on all types of electrical wires and cables. 2 1-866-254-0962www.megger.com Introduction Testing the quality of the grounding system has been a critical part of any electrical maintenance program for many years. For every 10 °C (18 °F) below base-line value, the resistance value halves. 1000 ... Microsoft PowerPoint - GEQ Interpreting Megger Readings Guide 020520 Oh yes, and I did forget to tell him that for general troubleshooting, it is a good idea to first take motor megger readings from the t-leads at the bottom of the controller, so that you also check the wire going to the motor from the controller at the same time. Fluke's digital insulation resistance testers provide reliable results whether you work on motors, generators, cables, or switchgear Good insulation shows a continual increase in resistance (see curve D) over a period of time (in the order of 5 to 10 minutes). 18) 2 Reference 18 (page 77) resistivity (ohm-cm) Whether you use a Megger insulation tester monthly, twice a year, or once a year, it is important to be able to interpret the results. insulation resistance readings are affected by dirt, moisture and heat. When the meter is connected for a duration, it will gradually and continually exhibit increasing Ohm readings. If the motor is kept in a place with high humidity, a periodical inspection is necessary. If we choose 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. Note that for low resistance readings, more corrosion was found. 1000 ... Microsoft PowerPoint - GEQ Interpreting Megger Readings Guide 020217 Ground electrodes are used to provide a safe path to earth for the dissipation of fault currents, lightning strikes, static charges and EMF/RFI signals. Download. ( Crank Type) I own a 500 volt Megger. 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. The results obtained from IR Test are not intended… Megohmmeter (famous as Megger*) is an electrical instrument used to measure the electrical resistance of insulators. display uses the Megger digital/analogue arc, providing indication of fluctuating readings while the dual digital readout shows precise values of key measurements simultaneously with the test parameters, such as the output voltage on insulation testing as well as the resistance value in MΩ. I have had it for over 30 years , and it still works like new . For every 10 °C (18 °F) devia-tion above baseline temperature, the resistance value doubles. Polarization Index. Very often a megger is used to check the insulation of cable jackets, motors, and other high voltage (HV) equipment to ensure the safety of equipment. Set the voltage setting of the insulation resistance tester to 500V. If the megger reads a resistance between 1-1.25 on your meter, then the cable passes. Polarization Index, or PI, is a ratio of the megohms after 10 minutes divided by the megohms after 1 minute. This is caused by the absorption; good Megger insulation tester readings should be considered relative and are known to be quite different with each reading. I'm 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.