High voltage testing of cables pdf

For power engineers, large power transmission cables are of importance, and hence testing of power cables only is considered here. The failure rate for accessories 33% is higher than for cables 17%. 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. Normally, the voltage drop on the power feed side and ground side wires, connectors, and connections should not exceed 0. Cables for 3000 and 6000 volts exist, but the majority of cables are used from 10 kv and upward. Medium high voltage cable components conductor the current carrying components are made of copper or aluminum. Products hvi manufactures industryleading hv test sets and backs every product with outstanding customer support.

Aluminum is less expensive but less efficient, requiring a larger conductor diameter to carry an equal electrical load when compared to a copper conductor. Conductors used with modern solid dielectric cables come in four. Testing of electrical power cable type test acceptance. The maintenance test level is about 75% of the acceptance test level. As a routine test, the cable is tested applying an a. High voltage engineering notes hve notes hve pdf notes. The instrument used for this measurement shall have a. Those of 10 to 33 kv are usually called medium voltage cables, those over 50 kv high voltage cables. Diagnostic testing of underground cable systems cable diagnostic focused initiative doe award no. The following details are required for calculation. High voltage engineering pdf notes hve notes pdf smartzworld. Relationship between capacitive and resistive currents the ratio of the two currents i r i c is the tangent of the angle.

The values associated with the testing methods shall be in accordance with the applicable table 100. Type testing of cables and accessories is not a superfluous luxury. From testing devices with ac or dc voltage, from low to high voltage, con dition evaluation. For this reason, it is common practice to cut off a portion of cable after pulling to assure an undamaged end. Dc high potential testing dc hipot testing purpose dc hipot testing is used for proof testing shielded cables 5kv to 46kv in the field. 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. Jul 23, 2018 cables are very important electrical apparatus for transmission of electrical energy by underground means.

Vlf testing of high voltage cables, state of the art. 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. If a vlf test is too low in voltage andor too short in duration, more harm than good may result. Approximate 3 meters long core is removed as sample from the finished cable or cord. Vlf operation reduces the power required to load cables which present a capacitive load. Testing of hv cables supplementary information page 1 of 24 reference sp0407r02 ver 2 ergon energy corporation limited abn 50 087 646 062 1. 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. The complete guide to electrical insulation testing. High voltage xlpe cable systems techincal user guide brugg cables page 6 2. Testing cables with high voltage cirris systems corp. Example of asbestos paper insulation wrap on highvoltage cable inside an underground cable vault. When the various layers are removed, cuts should extend only partially. Medium high voltage cable preparation it is necessary to begin with a good cable end. High quality installation work performed by abb certified field personnel is essential for achieving the low.

This testing of high voltage hv cables manual has been developed for use by. A 10,000 15 kv cable has approximately 1uf of capacitance. Tests described in this technical guideline are divided into the following categories. 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. 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 medium voltage cable dominates in the underground cable market segment. Pdf pa new testing method for testing long and extralong high voltage cables, called differential resonance technology drt is presented. Cables are tested for withstand voltages using the power frequency a. Perform the test as instructed to make best use of vlf technology.

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. Electrical utility field testing for mediumvoltage cables. Careful consideration should be given to safety precautions for high power. Damped alternating current voltages are generated by charging the test object to a predetermined voltage level and then discharging its capacitance through a suitable.

Cables with extruded insulation for system voltage above 30 36 to 500 550 kv. Pdf vlf testing of high voltage cables, state of the art. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. Power cables are mainly used in distribution networks of power utilities, in industries, in mines etc. This is primarily due to the availability of other test methods and the high levels of power. They are also very important means for transmitting voltage signals at high voltage test on cables.

Feature to differentiate power cables is the voltage grade, which is indicated as quotient u 0 u, where u 0. If so, dc testing has the considerable advantage of being the simplest and most convenient to use. The test measures the insulation resistance between the phases andor between phase and ground. Perform an insulationresistance test utilizing a megohmmeter with a voltage output of at least 2500 volts. 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. Cable types, design, and associated insulation faults. 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. In industrial high voltage motors and generators, electrical stress can reach several kilovolts per millimeter and this can give rise to pd either. Engineering data for copper and aluminum conductor electrical. The minimum insulation resistance to earth or between phases shall be 100 megohms. The short circuit test or high voltage test can be programmed out of the test.

Vlf cable test voltage ieee standard high voltage inc. Testing of insulators and bushings, testing of isolators and circuit breakers, testing of cables, testing of transformers, testing of surge arresters, radio interference measurements. 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. Maximum voltage, designated um, is the permissible highest voltage for which the equipment is specified see also standard iec 38. 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.

Pdf because cables and accessories are an important art of the electric infrastructure they are subjected to several tests. During the test cables are subjected to a test voltage significantly higher than what they experience during normal operating conditions. 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. A key to good cable preparation is the use of sharp, high quality tools. Is 7098 p3 or iec 60840 or iec 62067 pvc st 2 y pe. 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. Commissioning tests for hv cables up to 33kv swp ergon energy.

Technical cable testing 82 novemberdecember 2015 monitored withstand testing for mv cables a high voltage withstand test, in particular dc on xlpe cables is likely to lead to their destruction. The fundamental difference between ac and dc high voltage testing is the avoidance of space charge effects. Low voltage and high voltage cable testing electrical. 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. 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. Voltage drop testing is important because high resistance can prevent proper circuit operation. Where applicable or needed, some specific requirements not in the applicable standards or recommendations are stated. High voltage is defined as any voltage over volts. Very low frequency vlf withstand testing is the application of an ac sinusoidal waveform, generally at 0.

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. Low voltage and high voltage cable testing low voltage xlpe distribution cables. Dc cable testing is also outlined in section 6 of our cable installation manual1 see pages 8084 available on the web at. Basics of highvoltage test techniques abstract highvoltage hv testing utilizes the phenomena in electrical insulations under the in. Testing and commissioning of mvhv cables example of asbestos paper insulation wrap on high voltage cable inside an underground cable vault. Several layers of the soft and friable insulation are. High voltage test on cables dielectric power factor test. Ac high voltage test equipment design vlf operation reduces the power required to load cables which present a capacitive load. 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. Netaworld online versus offline partial discharge testing for cable assessment 65 figure 1. High power testing involves a special type of high voltage measurement in that the level of current is. High voltage xlpe cable systems techincal user guide brugg cables page 3 1. Partial discharge pd occurs in high voltage hv electrical equipment like cables, transformers, motors and generators.

Of all systems in a hv plant, cable systems must satisfy possibly the widest range of test requirements. High voltage xlpe cable systems technical user guide. Angle increases with increasing voltage, indicating a high resistive current element to the insulation. Ieee guide for field testing and evaluation of the insulation of shielded power cable systems rated 5 kv and above. Rated 5 kv and above with high direct current voltage. General information on high voltage cable systems 1.

Home technical articles testing and commissioning of mvhv cables example of asbestos paper insulation wrap on high voltage cable inside an underground cable vault. Rated voltage, designated u, is the effective phasetophase voltage. Similarly ac tests at low frequency vlf tests are of themselves not necessarily indicative of the health of a cable. With all the high voltage being used, what about my safety. Several layers of the soft and friable insulation are wrapped around the cable in long, wide strips. The dielectric voltage withstand test is commonly known as the hipot test. Nkt has a fleet of mobile resonant test systems to conduct hv tests of your cables. Individually test each conductor with all other conductors and shields grounded. 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. Ieee safety recommendations for high voltage testing.

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. Figure 1, cross section of a high voltage cable, 1 conductor 3 insulation 2 and 4. Ac resonant test systems for onsite testing and offline. Performed by stressing the insulation of the product far beyond what it would encounter during normal use. General cable cable installation manual for power and control cables the dc or vlf very low frequency typically 0. 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. To select the cable it is necessary to consider whether the specific system and installation conditions and requirements can be fulfilled. White paper controlling partial discharge in high voltage. 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.

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. Designed to verify that the insulation of a product is adequate enough to withstand high voltage. First, to test a cable with 60 hz power requires a very high power supply. Testing of high voltage cables manual horizon power 1st edition february 20 prepared by field practices. For testing of porcelain insulators and in high tension cables, voltages as high as 2000 kv may be used. It is not practical, nearly impossible, to test a cable of several thousand feet with a 60 hz supply. Explore our product lines and discover how hvi can help make your hv testing safer, faster, and easier to perform. 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. When vlf withstand testing cable, the proper test voltage and time duration are critical for the success of the test.

The power cable market can be segmented into three areas based upon the voltage class of the cable. 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. High voltage test cable illustration e ground test cable. Jun 07, 2011 low voltage and high voltage cable testing low voltage xlpe distribution cables. 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. The guard terminal is useful when measuring very high resistance values. Low voltage and high voltage cable testing electrical notes. Ac is therefore recommended in most cable testing standards. Horizon power employees and service providers engaged to perform. Engineering data for copper and aluminum conductor. 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. Voltage drop testing is commonly done to check wires, connectors, and connections for excessive resistance.

The lower the frequency, the less current and power needed to test high capacitance loads. The only way to field test high capacitance loads with ac voltage, like cables and motorsgenerators, is to use a vlf ac hipot. 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. Insulation resistance testing is a nondestructive test procedure. The high voltage ac withstand test ensures the electrical integrity of the insulation system with regards to its dielectric strength while the partial discharge test identifies significant voids and possible contaminants with surrounding voids that may be present within the dielectric material. It is a kind of very small spark that occurs due to a high electrical field. Perform a shieldcontinuity test on each power cable by ohmmeter method. Testing of high voltage cables manual horizon power.

Testing of high voltage cable systems svenska kraftnat. Also, many tests are measured on a comparative basis. Diagnostic testing of underground cable systems cable. Hipot test is the most common type of electrical safety test. The typical high potential hipot test is an example of a type 1 field test. Compare bolted connection resistances to values of similar connections. A high voltage insulated cable circuit consists of three singlecore cables or one threecore cable with high voltage sealing ends at each end. Cables shall be tested for insulation resistance with an insulation tester i. Understanding insulation resistance testing pdf 0712 technical assistance 800 34391.