For proof tests of new unused motors, the test voltages are as follows per ieee 95, iec. Now they can be used for field testing cable and rotating machinery. Using the right diagnostic tester keeps equipment operational so that users are able to ascertain whether insulation is functioning properly. 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. Coil testing in a manufacturing environment by anthony pretto, international electromagnetics, inc. Safety guidelines for hipot testing and setting up a safe. Press the green test button and observe the following precautions. Ac hv test value should not surpass 75% of the factory test value. Hi pot testing can be conducted with a dc potential or ac potential and can be applied as a type 1, withstand test or a type 2, diagnostic test. Oct 31, 2017 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.
D700c30347tzc 420 vac supply leads ground 378 vac 535 vdc 1 second. 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. Hipot testing has long been a standard procedure for assuring the electrical safety. Shari richardson is a director of engineering and the lead engineer on all medical applications at quadtech. The test may be between mutually insulated sections of a part or energized parts and electrical ground. The dielectric voltage withstand test page 2 the dielectric voltage withstand test is an integral part of the product safety evaluation of electrical and electronic devices, and provides manufacturers with important information regarding the quality and appropriateness of the chosen insulation system. When ac hi pot 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.
While the power is off, connect ac power supply to the unit and 120v. 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. High potential hipot cable system testing can be performed using dc, ac or very low frequency ac also known as vlf test voltage. He programs the first step of the hipot tester sequence for 250 v, 60 hz.
As we know,a multimeter or ohm meter reading only can determine if a motor winding is open or shorted but cannot checked winding insulation condition. Oct 23, 2012 understanding hipot certification testing navigating a maze highpotential safety standards can be a daunting task. Nov 26, 2018 a few simple steps ensure testing takes place safely when potentially lethal voltages and currents are involved in the testing process. Insulation resistance testing is a nondestructive test procedure. This article discusses the pitfall one must be wary of when performing hipot tests. Electrical safety testing reference guide power sources. Test procedure zthe screw needs to be removed only for hipot test and shall be returned aftertesting. Misinterpretation of the relevant standard may result in the product being subjected to a hipot design verification test to the levels described above. Understanding hipot certification testing electronic design. The hipot test the dielectric voltagewithstand test is commonly known as the hipot test. Low voltage directive provides structure and procedure of product safety test. Very low frequency vlf withstand testing the basics.
Figure 4typical record of insulation resistance of a mill motor. If the display passes, disconnect the hipot tester. Due to the nature of a dc withstand test, setting high and low leakage limits can prove difficult. A distinction must be made here regarding the test of dielectrics vs the high voltage test of individual nets. In definition, it is the application of an ac voltage higher than the rated voltage for a specified time for the purpose of determining the adequacy against breakdown of. Ac testing, however, does have some disad vantages. Measuaring motor insulation using hi pot tester electrical. For proof tests of new unused motors, the test voltages are as follows per ieee 95, iec and ansieasa ar100. Safety, operation, and procedure instructions for the pts. 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. The powersupply vendor verified that the test procedures and powersupply installation were correct.
The description of these tests will not apply to watercooled stator windings since the test procedure and analysis differ for watercooled units. Ac testing also has the advantages of checking both polarities of voltage and of not needing to discharge the dut after testing is complete. Vlf testing is used for any application requiring ac testing of high. Makes sure current flows easily from one point to another point. This discussion will also focus on testing of stator windings and not on testing individual bars or coils. Hipot testing has long been a standard procedure for assuring the electrical safety compliance of electronic equipment. Electrical safety testing reference guide touch area. The current meter on the pts series also has a megohmmeter scale to allow for easy. 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. Between contacts and shielded, the puncture voltage must not less than 1. Hipot test is short name of high potential high voltage test and it is. A few simple steps ensure testing takes place safely when potentially lethal voltages and currents are involved in the testing process. Hipot testing has long been a standard procedure for assuring the electrical safety of electronic equipment. Testing of high voltage cables manual horizon power.
Hi pot dielectric breakdown automated verification howto. The buttons are positioned a safe distance away from the high voltage. These notes are all available for download in adobe pdf format. Neta test forms tests performed by testing organization. For good insulation, the resistance usually reads in the megohm range.
Hipot testing involves using a high potential voltage to test insulation. 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. Ieee std 400 provides additional information on dc testing and evaluation of the insulation of shielded power cable systems. The dielectric withstand hipot test in compliance magazine. 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.
Hipot tester made for hipot test, flash test, dielectric. Ac hipot test the ac hipot test is a highpotential test performed with ac voltage at 60 or 50 hz. Reverse side of card at right is used to record the test data. However, the standards state that production hi pot testing should not exceed 1,500vac, or its dcrectified equivalent of 2,121vdc, from input to output or input to ground. Figure 3typical scale on the megger insulation tester.
Such testing can be conducted as an acceptance test for new installations or as a maintenance test for existing. High potential testing hipot testing can be conducted with a dc potential or ac potential and can be applied as a type 1, withstand test or a type 2, diagnostic test. Hipot test is the most common type of electrical safety. In some ways a hipot test is the opposite of a continuity test. The test is a means to qualify a devices ability to operate safely during. Quality control is an integral part of any manufacturing process. A properly wired and insulated electrical system will have negligible current flow during this test. Its just an ac hipot but with a lower frequency output. A very low frequency vlf withstand test is an ac withstand test usually carried out at a frequency between 0.
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 test setup and procedures are identical for both ac and dc hipot. The megger insulation tester is essentially a highrange resistance meter ohmmeter with a builtin directcurrent generator. We have all used ac hipots for decades to test various types of equipment. Thus, a dc hipot test voltage is often derived from a typical ac hipot test voltage which is proven to work well. 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. As long as the buttons are held down the hipot test will happen.
A hipot test checks that no current flows between points where there should be no current. 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. Ipctm650 embedded devices test methods subcommittee. Very low frequency vlf withstand testing is the application of an ac sinusoidal waveform, generally at 0. Driver model mov clamp voltage hipot test location test voltage ac test voltage dc duration from. These features are used with a dc hipot or ir test. If the display should fail the test, the red overload failure indicator will light up, the test voltage will disengage and the tester will emit a continuous beep. This high voltage test also called dielectric strength test, hipot test, hi pot test, breakdown test or flash test is made to stress the device under test to an ac or dc high voltage and check that there is no breakdown nor perforation happening. Below are hipot test voltages for both dc hipot and ac hipot tests. Standard for acceptance testing specifications for electrical. Early commercial hipot testers were actually not much. Acceptable procedures for conducting hipot testing, although varying slightly in technique, have been standardized as either a withstand test or a timeleaking current test.
Connection method for power frquency withstand voltage test. Test button this is a momentary contact switch used to start a test. When this test is indicated the industry provides 3 venues for accomplishing this. One safe and effective testing method offered by industrial tests, inc. Ieee std 400 provides additional information on dc testing and evaluation of the insulation of shielded power cable systems c. As a part of that process, it is important to establish proper testing procedures in order to maintain efficient production. 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. 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. Hipot testing shall not be conducted on test specimens that have previously been exposed to high voltage levels or other similar testing. During the test cables are subjected to a test voltage significantly higher than what they experience during normal operating conditions. Hipot test makes surety of no current will flow from one point to another point. A hipot tester also checks that insulation distances and distances in the air are respected.
Connect the ground lead of the hipot tester to a suitable building ground or grounding electrode conductor. Once the insulation is charged full test potential, the leakage current drops off to near zero ma. 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. Dc hipot test at test start, there will be inrush current. Its important to remember that this method of arc detection is not an exact science. The dielectric voltagewithstand test is commonly known as. To allow a hipot test an operator must use each hand to hold down a button. 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. Withstand or hipot cable testing withstand or hipot testing is used to evaluate the condition of cable insulation during installation, acceptance, or maintenance testing. Test voltages and duration are shown below for customer use with the hipot testing procedure found in csac22. This type of system works for fast hipot tests but can be. Dc high potential testing dc hipot testing purpose dc hipot testing is used for proof testing shielded cables 5kv to 46kv in the field. This page introduces some of the concepts youll find in ac hipot testing on the easywire ch2.
Ac hipot testing there are no widely accepted test standards for ac hipot testing of cables, and power frequency ac hipot testing of cable systems is rarely performed. Most manufacturers recommend com plate inspections, external and internal, at intervals of from 6 to 12 months. Designed to verify that the insulation of a product is adequate enough to withstand high voltage. He programs the first step of the hipot tester sequence for 250 v, 60. The megger insulation tester is a small, portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. This kind of test is suited for testing high capacitance loads such. How dc hipot works dc voltage is applied to open disconnected windings by the hipot tester or motor analyzer. A hipot test can be very useful in helping you develop a process that builds high quality cables and wire harnesses. 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. Before moving on to the main hipot testing techniques, it is. The choice of the right method and the most appropriate instrument. Misinterpretation of the relevant standard may result in the product being subjected to a hi pot design verification test to the levels described above. The ac hipot test values for voltages up to 69 kv are presented in table 1. Hipot by definition via tm650 is the test of insulation of atypical potential layers, aka power and ground.
Cable types, design, and associated insulation faults. Ac hipot testing ac high potential tests are conducted at voltages above the normal system voltage for a short time. The following sections of the ansineta standard for acceptance testing specifications for. However, the standards state that production hipot testing should not exceed 1,500vac, or its dcrectified equivalent of 2,121vdc, from input to output or input to ground. This button may also be used to abort a test in progress. Measuaring motor insulation using hi pot tester 28012012 by lemau 1 comment when we need to evaluate the motor condition, hi pot tester or high potential tester is the common equipment are used.
Voltage motor testing will be submitted separately. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. It is the data behind the hipot test that can help manufacturers ensure the product is safe and consistent. The dc hi pot withstand test is a passfail test that has been applied to all types of cable and accessories. Understand that each step in the work plan must be executed as planned. The pts series of dc hipot test sets provide continuously adjustable output voltages for the test and measurement of leakage current in high voltage insulation. Dc hipot tester hipot test procedure electrom instruments.
Guidelines for high potential hipot dc testing of medium. Meanwhile, your heart palpitation unregulated and blood pressure falling down causes tragedy cant be redeemed. The test measures the insulation resistance between the phases andor between phase and ground. The test can be done at various times such as acceptance of new cable installation, maintenance testing to track insulation degradation and as a pre and post test for splicing existing cables to new ones. To reset the system for the next test, press and release this button. Jan 16, 2014 dc hipots can be used for the following testing applications. The dc hi pot leakage current technique, sometimes referred to as a megger test, involves the.
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. 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. Hipot test is short name of high potential high voltage test and it is also known as dielectric withstand test. If the hipot does not have a complete circuit, it cannot discharge the dut at the end of the test.
Factory hipot testing for ul606011 approved models with gas. Hipot test current, leakage current and insulation resistance. Other models in the 800 series follow a similar testing procedure, but today im demonstrate testing on a 15kvrated urd cable. With an ac hipot test, a long ramp time is usu ally not required except with certain sensitive devices. The dc hipot withstand test is a passfail test that has been applied to all types of cable and accessories. Ex perience has shown that a considerable expense is involved, some of. If you must stop the test for any reason, press the red high voltage off button. Performed by stressing the insulation of the product far beyond what it would encounter during normal use.
The complete guide to electrical insulation testing. Hipot test is the most common type of electrical safety test. Curve b shows same values corrected to 20c see page 22, giving a definite downward trend toward an unsafe condition. If either switch is released, the hipot test aborts. The ac hi pot test values for voltages up to 69 kv are presented in table 1. A hipot test starts with all of the points in a cable held at 0v. Performed by stressing the insulation of the product far. This is primarily due to the availability of other test methods and the high levels of power consumption. Hipot test voltages high potential test electrom instruments. Dec 01, 2011 the limited approach boundary for this hipot procedure at volts is 5 ft.
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