Hipot test is short name of high potential high voltage teat and it also known as dielectric withstand test. The surest way to weed out bad cables and accessories is to just perform a simple ac hipot test, just like we do with vacuum bottles, arrestors, hot sticks, switchgear bus and insulators, etc. The operators manual for the particular test set being used should be read and well. Repeat this test procedure for all circuit phase conductors testing each phase to ground and each phase to each. 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. While the dielectric voltage withstand test is widely used, the real objective of the test is often misunderstood, which may lead to incomplete testing or misleading test results. Standard for acceptance testing specifications for. Hipot testing involves applying an overvoltage to the cable system for a short duration to verify the dielectric integrity of the system cable, splices, and terminations. 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. Also, since the test takes only 5 10 minutes, the cable is not voltage stressed for a long enough period of time for breakdown to occur, unlike a vlf ac hipot test where up to 3 times normal.
Very low frequency vlf withstand testing is the application of an ac sinusoidal waveform, generally at 0. In most cases hipot testing is applied as a passfail or gonogo test. Cables passed a prequalification test on a 400 kv xlpe cable system according to the relevant international standard iec 62067 2001. Testing and commissioning of mvhv cables example of asbestos paper insulation wrap on highvoltage cable inside an underground cable vault. In some ways a hipot test is the opposite of a continuity test.
Yes the cable may fail under test if it has a severe defect, but thats the point of the test. Image you are bathing in bath tube, suddenly drier in operating dropping into bath tube, the current flows. Safety guidelines for hipot testing and setting up a safe. Certified copies of production sampling and completed cable test reports. A hipot test checks that no current flows between points where there should be no current. Ieee std 400 provides additional information on dc testing and evaluation of the insulation of shielded power cable systems. The typical highpotential hipot test is an example of a type 1 field test. Other models in the 800 series follow a similar testing procedure, but today im demonstrate testing.
The pilot should refer to the manual wiring of figure 1 or the relevant test transformer. Dc hipot tester hipot test procedure electrom instruments. Includes testing procedures provides guidelines for test voltages methods of evaluation. The procedure for vlf testing is nearly identical to that of dc hipot testing and is also conducted as a gonogo test. When vlf withstand testing cable, the proper test voltage and time duration are critical for the success of the test. 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 to the conducting wire at the point of connection. Confirm that all equipment or cable that is not to be tested is isolated from the circuit under test. Power cable testing and diagnostics overview testguy.
Testing of high voltage cables manual horizon power. The choice of testing techniques and procedures for medium voltage cables is now well defined and enables the implementation of effective plans for the proving cable fitness for service. This white paper seeks to clarify the theory of dielectric breakdown and the objective of the dielectric voltage withstand test. Performed by stressing the insulation of the product far beyond what it would encounter during normal use. A catalogue, for quick reference, of the range of megger test instruments for the maintenance of electrical power systems. A hipot test starts with all of the points in a cable held at 0v.
The test measures the insulation resistance between the phases andor between phase and ground. That is, with the same test connections and with the same test voltage applied for the same length of time. Hipot test is the most common type of electrical safety test. Warning the 955i is intended to be powered from a power. Sp0407r01 commissioning tests for new hv cables up to 33 kv job safety analysis sp0407r02 testing hv cables supplementary information sp0407r03. Remember, the point of the test is to help prioritize cable replacement, so absolute numbers are less important than test results comparing many cables. Dc hipot testing of solid dielectric cables can therefore make aged cables. General discussions for field testing of cables testing objectives. Timely conducted testing procedures can help notice the loss.
Very low frequency vlf withstand testing the basics. If too much current is flowing the cable fails the hipot test. Early commercial hipot testers were actually not much more than a variacdriven stepup transformer used to ramp up the test voltage and then dwell at the specified voltage for the prescribed time period all the while. Ac hipot testing stipulated in iec 60502 mv, iec 60840 hv and iec 62067 ehv as well as most cable testing standards testing at power frequency from 20 hz to 300 hz recommended high potential test level for acceptance testing ranges from 1. Find here insulation testing and continuity, power protection, power transformer testing, power cable infrastructure, cable fault location, general electrical test. Hipot test is a contraction for high potential hv testing. Acceptable procedures for conducting hipot testing, although varying. Insulation resistance testing is a nondestructive test procedure. 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.
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. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. Vlf cable test voltage ieee standard high voltage inc. The result obtained is a voltage value usually expressed in kilovolts kv.
This document will focus only on the tests that are of importance for field installers which are described as installation and maintenance tests. However, it provides limited knowledge of the cable condition other than whether the cable system withstood the voltage for the duration of the test or not. 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. The numerical data, formulas and other calculations provided in this document are. The international electrical testing association neta was formed in 1972 to establish uniform testing procedures for electrical equipment and apparatus. Neta developed specifications for the acceptance of new electrical apparatus prior to energization and for the maintenance of existing apparatus to determine its suitability to remain in service. Connect the opposite end of the test power cable to either outlet of the duplex box. Withstand or hipot cable testing withstand or hipot testing is used to evaluate the condition of cable insulation during installation, acceptance, or maintenance testing. Hipot testing is an abbreviation for high potential testing a category of electrical tests used to verify the. Welcome to the ninth edition of general cable s cable installation manual for power and control cables. When performed as type tests hipot tests are helpful in finding various important defects. Insulation resistance testing of low voltage cables in the. Hipot testing has long been a standard procedure for assuring the electrical safety compliance of electronic equipment.
The okonite company technical news engineering information the ofessional engineer frequency of field hipot testing when discussing field dc hipot testing of medium voltage epr and xlpe insulated cables, two questions that always come up are. Commissioning test for hv underground cable up to 33kv swp sp0407 field instruction sp0407c01 hv cable commissioning test report form sp0407c04 commissioning tool hv cables up to 33kv sp0506. Designed to verify that the insulation of a product is adequate enough to withstand high voltage. 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 limited approach boundary for this hipot procedure at volts is 5 ft. Cable types, design, and associated insulation faults. Testing cables with high voltage cirris systems corp. How to conduct a hipot test on a 11kv cable answer prabhu krishna. Several layers of the soft and friable insulation are wrapped around the cable in long, wide strips. The assumption is that if the insulation can withstand the significantly. This test required one year of operation, along with the thermal monitoring of. The complete guide to electrical insulation testing. Misinterpretation of the relevant standard may result in the product being subjected to a hipot design verification test to the levels described above.
Hipot testing procedure for withstand testing of hv coax. If the cable can withstand the applied voltage for the duration of the test, it is considered a pass. Nicked or crushed insulation, stray wire strands or braided shielding. 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. High voltage xlpe cable systems techincal user guide brugg cables page 2. If a vlf test is too low in voltage andor too short in duration, more harm than good may result. Guidelines for high potential hipot dc testing of medium voltage. This manual provides installation information for power and control cables for industrial. The dc hipot withstand test is a passfail test that has been applied to all types of cable and accessories. Electrical safety testing reference guide touch area.