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