Individually test each conductor with all other conductors and shields grounded. The values associated with the testing methods shall be in accordance with the applicable table 100. Hipot test is the most common type of electrical safety test. Several layers of the soft and friable insulation are. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. The following details are required for calculation. The test measures the insulation resistance between the phases andor between phase and ground. Engineering data for copper and aluminum conductor electrical.
To select the cable it is necessary to consider whether the specific system and installation conditions and requirements can be fulfilled. Normally, the voltage drop on the power feed side and ground side wires, connectors, and connections should not exceed 0. Voltage drop testing is commonly done to check wires, connectors, and connections for excessive resistance. There is a certain logic for a wider application of this principle on the testing of medium voltage cables, especially for offline pd and tan. These results can be compared to other cables tested to determine which cables are in need of immediate replacement and which can wait a bit longer. Netaworld online versus offline partial discharge testing for cable assessment 65 figure 1. Cable layout and system design the dimensioning of a high voltage cable system is always based on the specifications and demands of the project at hand. Very low frequency vlf withstand testing is the application of an ac sinusoidal waveform, generally at 0.
Nkt has a fleet of mobile resonant test systems to conduct hv tests of your cables. Vlf testing of high voltage cables, state of the art. Rated voltage, designated u, is the effective phasetophase voltage. Introduction this reference is intended to give a basic overview of insulating materials that can be used during high voltage withstand testing, in particular cable testing. Careful consideration should be given to safety precautions for high power. Low voltage and high voltage cable testing electrical notes. Angle increases with increasing voltage, indicating a high resistive current element to the insulation. Diagnostic testing of underground cable systems cable diagnostic focused initiative doe award no. If so, dc testing has the considerable advantage of being the simplest and most convenient to use. Commissioning tests for hv cables up to 33kv swp ergon energy. The correct phasing of all lv circuits shall be checked at all positions where the lv cables are terminated into fuse bases and where any lv cable is run from point to point. Aluminum is less expensive but less efficient, requiring a larger conductor diameter to carry an equal electrical load when compared to a copper conductor. Diagnostic testing of underground cable systems cable. Approximate 3 meters long core is removed as sample from the finished cable or cord.
High voltage test on cables dielectric power factor test. The maintenance test level is about 75% of the acceptance test level. It is a kind of very small spark that occurs due to a high electrical field. Voltage drop testing is important because high resistance can prevent proper circuit operation. The lower the frequency, the less current and power needed to test high capacitance loads. Perform a shieldcontinuity test on each power cable by ohmmeter method. High voltage test cable illustration e ground test cable. This testing of high voltage hv cables manual has been developed for use by horizon power employees and service providers engaged to perform construction and. Pdf vlf testing of high voltage cables, state of the art. For example, if you have a wire that connects two pins, the high voltage will be simultaneously apply to both of those pins and the entire wire will be raised in voltage. When vlf withstand testing cable, the proper test voltage and time duration are critical for the success of the test.
White paper controlling partial discharge in high voltage. For this reason, it is common practice to cut off a portion of cable after pulling to assure an undamaged end. Partial discharge pd occurs in high voltage hv electrical equipment like cables, transformers, motors and generators. General information on high voltage cable systems 1.
Is 7098 p3 or iec 60840 or iec 62067 pvc st 2 y pe. The medium voltage cable dominates in the underground cable market segment. High voltage xlpe cable systems technical user guide. Cable types, design, and associated insulation faults.
This is primarily due to the availability of other test methods and the high levels of power. Similarly ac tests at low frequency vlf tests are of themselves not necessarily indicative of the health of a cable. Testing of high voltage cables manual horizon power. They are also very important means for transmitting voltage signals at high voltage test on cables. Tests described in this technical guideline are divided into the following categories. A high voltage insulated cable circuit consists of three singlecore cables or one threecore cable with high voltage sealing ends at each end. Cables are tested for withstand voltages using the power frequency a. Explore our product lines and discover how hvi can help make your hv testing safer, faster, and easier to perform. Basics of highvoltage test techniques abstract highvoltage hv testing utilizes the phenomena in electrical insulations under the in. Where applicable or needed, some specific requirements not in the applicable standards or recommendations are stated. The voltage levels installation and acceptance are based on the most used, worldwide practices of from less than 2 u0 to 3u0, where u0 is the rated rms phase to ground voltage, for cables rated between 5 kv and 69 kv. This testing of high voltage hv cables manual has been developed for use by. The typical high potential hipot test is an example of a type 1 field test.
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. We also offer total turnkey solution for extra high voltage ehv cables which includes manufacturing, testing, supply of cables, supply of cable accessories, installation of cables and accessories, testing and. Testing of high voltage cable systems svenska kraftnat. The dielectric voltage withstand test is commonly known as the hipot test. Low voltage and high voltage cable testing electrical.
Dc high voltage testing of new xlpe cables is not recognised to cause cable deterioration, however in order to adopt a standard approach vlf ac testing is preferred instead of dc high. Feature to differentiate power cables is the voltage grade, which is indicated as quotient u 0 u, where u 0. This equipment can be used to conduct commissioning tests of your newly installed cables, recommissioning of repaired systems before reenergizing them and periodic testing of systems or spares to assess their condition. High voltage is defined as any voltage over volts. At the time of manufacture the entire cable is passed through a high voltage test at the rated voltage to check the continuity of the cable. High voltage xlpe cable systems techincal user guide brugg cables page 3 1. The guard terminal is useful when measuring very high resistance values. The minimum insulation resistance to earth or between phases shall be 100 megohms. Electrical utility field testing for mediumvoltage cables.
The power cable market can be segmented into three areas based upon the voltage class of the cable. Perform the test as instructed to make best use of vlf technology. Performed by stressing the insulation of the product far beyond what it would encounter during normal use. Hv routine test fields for extruded power cables n complete solutions including comprehensive technical support n reliable performance for even the highest cable ratings and testing levels n highest pd measuring sensitivity n power upgrades for testing of even ultralong power cables 9. Testing of electrical power cable type test acceptance. The only way to field test high capacitance loads with ac voltage, like cables and motorsgenerators, is to use a vlf ac hipot. Ac is therefore recommended in most cable testing standards. Ieee safety recommendations for high voltage testing. Of all systems in a hv plant, cable systems must satisfy possibly the widest range of test requirements. The complete guide to electrical insulation testing. High voltage xlpe cable systems techincal user guide brugg cables page 6 2. High quality installation work performed by abb certified field personnel is essential for achieving the low. Figure 1, cross section of a high voltage cable, 1 conductor 3 insulation 2 and 4.
Cables for 3000 and 6000 volts exist, but the majority of cables are used from 10 kv and upward. Power cables are mainly used in distribution networks of power utilities, in industries, in mines etc. High power testing involves a special type of high voltage measurement in that the level of current is. In industrial high voltage motors and generators, electrical stress can reach several kilovolts per millimeter and this can give rise to pd either. Insulation resistance testing is a nondestructive test procedure. Understanding insulation resistance testing pdf 0712 technical assistance 800 34391. First, to test a cable with 60 hz power requires a very high power supply. Horizon power employees and service providers engaged to perform. Continuity test checks surety of current flows easily from one point to another point while hipot test checks surety of current would not flow from one point to another point and turn up the voltage really high just to make sure no current will flow.
Ac high voltage test equipment design vlf operation reduces the power required to load cables which present a capacitive load. High voltage engineering pdf notes hve notes pdf smartzworld. Abb xlpe land cable systems 5 design, installation and testing installation of xlpe cable systems installation of cable systems includes trenching, cable pulling, clamping of cable, cable splicing as well as mounting of accessories. Jun 07, 2011 low voltage and high voltage cable testing low voltage xlpe distribution cables. From testing devices with ac or dc voltage, from low to high voltage, con dition evaluation. High voltage engineering and testing recommend this title to your library. Engineering data for copper and aluminum conductor. Designed to verify that the insulation of a product is adequate enough to withstand high voltage. A 10,000 15 kv cable has approximately 1uf of capacitance. The instrument used for this measurement shall have a. Testing cables with high voltage cirris systems corp.
As a routine test, the cable is tested applying an a. Vlf cable test voltage ieee standard high voltage inc. With all the high voltage being used, what about my safety. High voltage proof testing 52 53 high voltage dc field testing 52 dc field acceptance testing 52 test limitations 52 test notes 53 maintenance proof testing 53 frequency of tests 53 section 9 miscellaneous information 54 60 formulas for calculating charging current 54 capacitance of cables 54 insulation resistance 54 jacket materials. If a vlf test is too low in voltage andor too short in duration, more harm than good may result. Relationship between capacitive and resistive currents the ratio of the two currents i r i c is the tangent of the angle.
Dc high potential testing dc hipot testing purpose dc hipot testing is used for proof testing shielded cables 5kv to 46kv in the field. Pdf because cables and accessories are an important art of the electric infrastructure they are subjected to several tests. Testing of insulators and bushings, testing of isolators and circuit breakers, testing of cables, testing of transformers, testing of surge arresters, radio interference measurements. In 1996, the insulated conductor industry determined that dc withstand testing of the plastic xlpe insulation systems either in the cable factory as a routine production test or after installation as the higher voltage proof test was detrimental to the life of the insulation and therefore discontinued recommending dc testing. Cables with extruded insulation for system voltage above 30 36 to 500 550 kv. When the various layers are removed, cuts should extend only partially. It is not practical, nearly impossible, to test a cable of several thousand feet with a 60 hz supply. Also, many tests are measured on a comparative basis. Medium high voltage cable preparation it is necessary to begin with a good cable end. Products hvi manufactures industryleading hv test sets and backs every product with outstanding customer support. Dac voltage testing is one of the alternative methods of ac voltage testing and is applicable for a broad range of medium voltage, high voltage, and extra high voltage cables. Damped alternating current voltages are generated by charging the test object to a predetermined voltage level and then discharging its capacitance through a suitable. During the test cables are subjected to a test voltage significantly higher than what they experience during normal operating conditions. Example of asbestos paper insulation wrap on highvoltage cable inside an underground cable vault.
Jul 23, 2018 cables are very important electrical apparatus for transmission of electrical energy by underground means. Perform an insulationresistance test utilizing a megohmmeter with a voltage output of at least 2500 volts. Ieee guide for field testing and evaluation of the insulation of shielded power cable systems rated 5 kv and above. Testing of high voltage cables manual horizon power 1st edition february 20 prepared by field practices. General cable cable installation manual for power and control cables the dc or vlf very low frequency typically 0. Direct high voltage testing of cable insulation systems. Several layers of the soft and friable insulation are wrapped around the cable in long, wide strips. To hipot test a net, you connect all of the contacts in the net to high voltage and connect all other contacts in the device to ground. The sample then is so immersed in a water bath at room temperature that its ends protrude at least 200 mm above the water level. Those of 10 to 33 kv are usually called medium voltage cables, those over 50 kv high voltage cables. 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. The length of cable that can be tested at a given power increases by a factor of 5,000 compared to 50hz with consequent weight and cost savings. Home technical articles testing and commissioning of mvhv cables example of asbestos paper insulation wrap on high voltage cable inside an underground cable vault. Dc cable testing is also outlined in section 6 of our cable installation manual1 see pages 8084 available on the web at.
It has been established that dc high voltage testing of deteriorated xlpe cables can accelerate the deterioration process and lead to a reduction in cable life. The failure rate for accessories 33% is higher than for cables 17%. Pdf pa new testing method for testing long and extralong high voltage cables, called differential resonance technology drt is presented. Testing of hv cables supplementary information page 1 of 24 reference sp0407r02 ver 2 ergon energy corporation limited abn 50 087 646 062 1. Rated 5 kv and above with high direct current voltage. Compare bolted connection resistances to values of similar connections. Testing and commissioning of mvhv cables example of asbestos paper insulation wrap on high voltage cable inside an underground cable vault. Cables shall be tested for insulation resistance with an insulation tester i. Ac resonant test systems for onsite testing and offline. High voltage engineering notes hve notes hve pdf notes. Low voltage and high voltage cable testing low voltage xlpe distribution cables. For power engineers, large power transmission cables are of importance, and hence testing of power cables only is considered here. The short circuit test or high voltage test can be programmed out of the test. Maximum voltage, designated um, is the permissible highest voltage for which the equipment is specified see also standard iec 38.
After engineering evaluation of the effectiveness of a test voltage and the risks to the cable system, high direct voltage may be considered appropriate for a particular application. Conductors used with modern solid dielectric cables come in four. May 02, 2018 dac voltage testing is one of the alternative methods of ac voltage testing and is applicable for a broad range of medium voltage, high voltage, and extra high voltage cables. For testing of porcelain insulators and in high tension cables, voltages as high as 2000 kv may be used. 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 fundamental difference between ac and dc high voltage testing is the avoidance of space charge effects. Conductor copper cu or aluminium al stranded compacted conductor or cu segmental conductor or cu or al conductor with keystone shaped profiles longitudinal water sealing of conductor.
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