Once the insulation is charged full test potential, the leakage current drops off to near zero ma. A low voltage is applied from the chassis of the product to the ground pin to determine if the appropriate amount of current flows. Periodic offline partial discharge testing at very low frequencies vlf is a diagnostic method for monitoring the insulation degradation of medium voltage cable. Safety guidelines for hipot testing and setting up a safe. The choice of the right method and the most appropriate instrument before moving on to the main hipot testing techniques, it is. In the boost or voltage withstand test process, as a result of short circuit, flashover, breakdown, such as over current, the current trip of relay protection, automatic voltage regulator power that test materials are not up to standard, at this time regulator should be back to zero, cutting off power supply, inspect the test products. This type of system works for fast hipot tests but can be impractical for long duration hipot tests. A few simple steps ensure testing takes place safely when potentially lethal voltages and currents are involved in the testing process.
The hipot tester current trip level should be set high enough to avoid nuisance failure related to leakage. The test duration must be in accordance with the safety standard being used. Very low frequency vlf testing hipot testing california. The assumption is that if the insulation can withstand the significantly higher voltage for a given time it will be able to. Whether the hipot test is applicable for any specify device. After having verified that the test procedure was correct and that the supply was correctly installed, an investigation of the test voltage found that the voltage applied was in excess of 1,500vac, but not at the 3kv or 4kv level. The complete guide to electrical insulation testing. Continuity test checks surety of current flows easily from. As long as the buttons are held down the hipot test will happen. Mats can detect the presence of a person in the test area.
These numbers result from many years of vlf field use and research. The hipot test the dielectric voltagewithstand test is commonly known as the hipot test. How dc hipot works dc voltage is applied to open disconnected windings by the hipot tester or motor analyzer. Standard for acceptance testing specifications for. Hipot testing elecrical safety wire and cable shine.
Sci is a leading manufacturer of electrical safety testing instruments including multifunction electrical safety testers, hipot testers, ground bond testers and insulation resistance testers. Repeat this test procedure for all circuit phase conductors testing each phase to. It was not clear why the higher voltage test was being applied but the test lab was adamant that it was correct. The ac hipot test values for voltages up to 69 kv are presented in table 1. The current standards provided for the use of dc hipot testing for acceptance testing of cables are recognized by the current industry standards. Hipot or high potential testing is a nondestructive test that has many names. Acceptable procedures for conducting hipot testing, although varying slightly in technique, have been standardized as either a withstand test or a timeleaking current test.
Sci is a leading manufacturer of electrical safety testing instruments including multifunction electrical safety testers, hipot testers, ground bond testers, and other safety equipment. In this case the operator only needs to load the board to the machine and initiate the test. Timely conducted testing procedures can help notice the loss of cable insulation integrity, spot signs of its deterioration caused by aging, and therefore prevent cable failure. The above information describes vlf withstand testing, where the intent of the test is to apply a sufficient test voltage for a long enough time to. Hipot step voltage tests provide much more information than a 1minute hipot test because the data is recorded as the voltage is raised. A dielectric withstand test or high potential or hipot test is an electrical test performed on a component or product to determine the effectiveness of its insulation. By charting a current vs voltage curve, one can usually tell if the leakage current is mainly due to contaminated dirty windings, or due to a breakdown of the insulation as shown in the pictures below. If a display fails the onesecond test method, redo the test using the sixtysecond etl test outlined below, as required by article 36 of ul standard 1433. To reset the system for the next test, press and release this button. Press the green test button and observe the following precautions. The purpose of the dielectric withstand hipot test is to determine whether the insulation from the primary circuit to grounded or accessible parts has sufficient electric strength to withstand the normal overvoltages which could occur in service. This technical article provides general guidelines for high potential hi pot dc testing of mv power cables.
Image you are bathing in bath tube, suddenly drier in operating dropping into bath tube, the current flows from drier through your body to ground under this situation. The existence of an ieee standard does not imply that there are no other ways to produce, test, measure, purchase, market, or provide other goods and services related to the scope of the ieee standard. Dry testing transformer series is produced, it is completely changed by the backward state of old test transformer stupid, big and heavy, it can produce our matching mounted on a highvoltage silicon stack to provide dc highvoltage test power supply, with a control box,automatic protection microammeters, gap and other ancillary equipment. Dielectric withstand or hipot test the dielectric voltagewithstand test, or hipot high potential test, is designed to stress the insulation of your product far beyond what it will encounter during normal use. Electrical safety testing reference guide touch area. It is the data behind the hipot test that can help manufacturers ensure the product is safe and consistent. Therefore, if a test of an installed motor in a plant fails above peak operating voltage, it. For additional information, questions, or comments, feel free to contact us at. The dielectric withstand hipot test in compliance magazine.
Why is a vlf hipot used instead of a regular 60 hz model. Dc high potential testing dc hipot testing purpose dc hipot testing is used for proof testing shielded cables 5kv to 46kv in the field. Dc hipot tests procedural differences breakdown vs. Voltage withstand test of time free to set up digital f. The hipot test is usually a 100% production line test and can be performed using either an ac or a dc voltage. The hipotronics hd11s tester supplies the needed voltage and measures the current leakage. Dielectric voltage withstand test hipot leakage current and dielectric breakdown general hipot test considerations ac vs. Arcing ground continuity test ground continuity test considerations ground bond test ground bond test considerations the ground bond test and the hipot test insulation. Hipot test is a contraction for high potential hv testing. Some people, when faced with the challenge of performing a test, become uneasy at the thought of working with a highvoltage system. Withstand test apply high voltage on power and ground. With wire harnesses and custom cable assemblies, this type of testing service is used to verify the correct operation of safety circuits. One safe and effective testing method offered by industrial tests, inc. Withstand or hipot cable testing withstand or hipot testing is used to evaluate the condition of cable insulation during installation, acceptance, or maintenance testing.
Designed to verify that the insulation of a product is adequate enough to withstand high voltage. The mat can be used to automatically disable or abort. There are two variations of the stepped dc hipot test. Inspect whether leakage current of acdc power flows to ground terminal is over standard. Hipot test is the most common type of electrical safety test. Join us as we take you to our whiteboard where we give you a visual diagram of the hipot test, then show you. Megger hipot tester hipot testers are high voltage testing instruments used predominately to test and confirm product specifications, as well as electrical breakdown limits. Dielectric strength test dielectric tests are used in the industry to inspect a wide variety of products, devices, and equipment. Vlf cable test voltages and time durations are set by ieee standard 400. The implication of dc hipot testing in the premature failure of extruded solid dielectric cables led to the development of ieee docuements ieee guide for field testing and evaluation of the insulation of shielded power cable systems and ieee 400. All tests made following cable installation and during the warranty period must be performed in accordance with the applicable specifications. Remarkable is that safety standard offering basic safety test and method. It is not practical, nearly impossible, to test a cable of several thousand feet with a 60 hz supply.
Standard for acceptance testing specifications for electrical. In the last few years, hipot and continuity tests have resulted in the highest failure rates of any measurements we make. My colleague uses a programmable acdc hipot tester to 1 determine that a unit under test is truly connected to the hipot tester and 2 conduct a dc hipot test. Dc hipot tester hipot test procedure electrom instruments. Using the right diagnostic tester keeps equipment operational so that users are able to ascertain whether insulation is functioning properly. The megger insulation tester is essentially a highrange resistance meter ohmmeter with a builtin directcurrent generator. Understand that each step in the work plan must be executed as planned.
Then a single wire or network of connected points called a net is disconnected from 0v and connected to the ac source see figure 2. Insulation resistance testing is a nondestructive test procedure. Guidelines for high potential hipot dc testing of medium. The test voltages to be used vary depending upon whether the device or circuit is low or high voltage, a primary or control circuit and whether tested at the factory or in the field. Given this range of products, robert hydraulique inc. This button may also be used to abort a test in progress. Dec 01, 2011 hipot test is short name of high potential high voltage teat and it also known as dielectric withstand test. Jun 16, 2016 performing a high potential test at 18. The dc voltage potential in the windings is rapidly raised to a predetermined level, or raised in steps up to this level, depending on what test method is used.
Dc hipot test at test start, there will be inrush current. If the hipot does not have a complete circuit, it cannot discharge the dut at the end of the test. Hipot testing has long been a standard procedure for assuring the electrical safety. Hipot testing is an abbreviation for high potential testing a category of electrical tests used to verify the effectiveness of electrical insulation in transformers, motors, printed circuit boards, electrical sub. Ac hv test value should not surpass 75% of the factory test value. Manufacturers of testing instruments and the agents responsible for establishing test procedures are sometimes at a loss to explain the how and why of a test and the true meaning of the test results. Dec 30, 2019 dc hipot tester hipot test procedure electrom instruments this current typically drops to zero within seconds after the test voltage provided by the motor tester is stable. With the proper programming interface to the hipot analyzer this test can reduce much time.
Ac hipot tests 15 dc hipot tests 15 arcing 16 line regulation 17 load regulation 17 ramping 18 minmax current detection 18 ground continuity test 18 polarization test 19 ground bond test 19 insulation resistance test 20 measurement procedure 21 dielectric absorption 21 charging current 21 leakage current 21 leakage current test 22. A hipot test starts with all of the points in a cable held at 0v. Jul 31, 2017 the purpose of the dielectric withstand hipot test is to determine whether the insulation from the primary circuit to grounded or accessible parts has sufficient electric strength to withstand the normal overvoltages which could occur in service. Watch the ampere meter while the voltage is increasing if the value hits the current limit before the test voltage is reached, you may have to increase the voltage ramp time to offset for the capacitive load. If either switch is released, the hipot test aborts. A ground continuity test assures the ground wire of a product is intact. Jan 16, 2014 dc hipots can be used for the following testing applications. The hipot test procedure described in figure 3 will be discussed first. Figure 4typical record of insulation resistance of a mill motor. Hipot test makes surety of no current will flow from one point to another point. This current is present during the atomic and any molecular polarization of the insulation, and is the current one is interested in during a pi test. The test is a means to qualify a devices ability to operate safely during.
The operators guide to electrical product safety testing. It is known by a number of names such as dielectric strength test, dielectric voltage withstand. The choice of the right method and the most appropriate. For good insulation, the resistance usually reads in the megohm range. He programs the first step of the hipot tester sequence for 250 v, 60. The test time for most standards, including products covered under iec 60950, is 1 minute. An untrained employee should not be able to have free access to the testing area particularly when tests are being performed. Due to the nature of a dc withstand test, setting high and low leakage limits can prove difficult. Complete tests 1 and 2 for each winding of a threephase transformer individually with the remaining windings kept open. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. Hipot test current, leakage current and insulation resistance. Since the dc is free of capacitive division, it is more effective in picking out. Performed by stressing the insulation of the product far. Test button this is a momentary contact switch used to start a test.
Meanwhile, your heart palpitation unregulated and blood pressure falling down causes tragedy cant be redeemed. The test connection arrangement is shown in figure 2 c. An arbitrary test voltage level could result in a cable failure in a circuit that would otherwise have provided long trouble free service at normal operating ac voltage. Withsta nd test apply high voltage on power and ground terminal circuit of product to measure its collapse status. High voltage dc cable testing both dc hipot testing and vlf testing can meet the needs of laminated paper cables such as pilc and newly installed solid dielectric cables such as xlpe. Ac hipot testing ac high potential tests are conducted at voltages above the normal system voltage for a short time. The pairs are programmed in an adjacency method for the flying probe.
Better and easier setup for production line hipot testing. The dielectric voltagewithstand test is commonly known as. Hipot test standards dc hipot test analysis electrom. Figure 3typical scale on the megger insulation tester. The test measures the insulation resistance between the phases andor between phase and ground. Designing hipot test stations an overview dielectric withstand hipot testing is the most accepted method of ensuring that primary wiring and components are isolated from the safety ground. Dc hipot test passfail analysis a dc hipot test is done at a voltage higher than the peak operating voltage of the device under test dut, where peak voltage rms voltage x 1.
Hipot setup and testing for hipotronics hd103 and hd106 acdc voltage testers overview to ensure your own personal safety and the safety of your coworkers, and to be sure that our displays are suitably tested to ensure customer safety, it is essential that you understand the proper setup and use of our hipot testers. When combined with a ground continuity test to ensure integrity of the safety ground between the appliance and. Curve b shows same values corrected to 20c see page 22, giving a definite downward trend toward an unsafe condition. 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. All of these tests are designed to make sure that the insulation used in. The test may be between mutually insulated sections of a part or energized parts and electrical ground. First, to test a cable with 60 hz power requires a very high power supply. Reverse side of card at right is used to record the test data. Cable types, design, and associated insulation faults. When ac hipot tests are used for routine maintenance, the power transformer can be examined at rated voltage for 3 min instead of testing at 65% of factory test voltage. Hipots are also referred to as high voltage testers, dielectric testers, dielectric withstand, or breakdown testers. The megger insulation tester is a small, portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. During cable pulling, cable is sometimes subjected to physical stress due to excessive force exerted on it that could eventually leads to damaging the outer layer parts that serve as primary protection of the cable.
Ieee std 400 provides additional information on dc testing and evaluation of the insulation of shielded power cable systems c. Shari richardson is a director of engineering and the lead engineer on all medical applications at quadtech. Sci electrical safety testers, hipot testers, ground bond. Between contacts and shielded, the puncture voltage must not less than 1. Sedding, qualitrol iris power 1 abstract it has long been known that comparing the partial discharge results obtained from a single machine is a valuable. Hipot test is the most common type of electrical safety. Hipot testing from shine detects the absence of current flow between two points. Vlf cable test voltage ieee standard high voltage inc. This guide provides a general overview of the regulatory framework and approval process and explores the specific manufacturing responsibilities and test procedures associated with electrical safety testing.
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