A key to good cable preparation is the use of sharp, high quality tools. The dielectric voltage withstand test is commonly known as the hipot test. This overview is provided as an insight into understanding of the nature of inservice cable degradation and some of the more commonly used diagnostic techniques commercially available for performing tests in the field on extruded, medium voltage, shielded power cables. 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. Field testing of mediumvoltage cables cable degradation and diagnostic tests. For this reason, it is common practice to cut off a portion of cable after pulling to assure an undamaged end. This overview is provided as an insight into understanding of the nature of inservice cable degradation and some of the more commonly used diagnostic techniques commercially available for performing tests in the field on extruded, mediumvoltage, shielded power cables. Cable installation manual for power and control cables ninth edition, september 2011 2. In accordance with icea, iec, ieee and other power cable consensus standards, testing.
These numbers result from many years of vlf field use and research. Standard for acceptance testing specifications for. Method statement for installation of high voltage hv cables. Smart interlocking padlocking system for maximum operator safety. Embedded cable testing compartment, easy and safe cable testing without cable connection removal. All tests made following cable installation and during the warranty period must be performed in accordance with the applicable specifications. Weems tn1452 20 pp illus august 1976 unclassified 1. Medium voltage soft starters will have their starting and stopping functionality demonstrated by starting and. Figure f2 cable feed into conduit at floor level c from cable reel to cable tray, the cable is fed from the top of the reel to maintain required curvature. Testing of hv cables supplementary information page 1 of 24 reference sp0407r02 ver 2 ergon energy corporation limited abn 50 087 646 062 1.
It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. The above information describes vlf withstand testing, where the intent of the test is to apply a sufficient test voltage for a long enough time to. Dac voltage testing is one of the alternative methods of ac voltage testing and is applicable for a broad range of mediumvoltage, highvoltage, and extrahighvoltage cables. Vlf hipots are also widely used for testing newly installed andor repaired cable before reenergizing to insure the cable is. This method statement defines the procedure step by step to implement the correct practices for installation of high voltage hv cable in order to ensure that the job execution complies with the project requirements and serves the intended function to satisfactory level. The medium voltage switchgear ax1 is not just a medium voltage cubicle, but also a complete switchgear systeminstallation. Hipot test is the most common type of electrical safety test. Damped alternating current voltages are generated by charging the test object to a predetermined voltage level and then discharging its capacitance through a suitable inductance. Individually test each conductor with all other conductors and shields grounded. The voltage of the cable must be chosen according to the maximum voltage um in. Typically, the applied test voltage is raised in steps, with measurements first taken up to 1uo, or normal line to ground operating voltage. Technical note voltage cable splicing and cable termination.
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. The construction of the 515 kv type vaccladw metalclad switchgear allows for the placement of circuit breakers in the upper or. What is the permissible leakage current value for a 11kv cable. Medium voltage switchgear ax1 is described in many different publications and even in a. This means that all high voltage parts are housed in the encapsulated main circuit enclosure and are inaccessible from the outside. Vlf cable test voltage ieee standard high voltage inc. Vlf cable testing very low frequency is a technique for testing of medium and high voltage mv and hv cables. Electrical utility field testing for medium voltage cables this document outlines the various methods for field testing medium voltage cable either during or after installation. Ieee guide for field testing of laminated dielectric, shielded power cable systems rated 5 kv and above with high direct current voltage. Designed to verify that the insulation of a product is adequate enough to withstand high voltage. Selection of the protection system and relays depends on and is correlated with the plant characteristics, type of industrial process and its service continuity requirements, with the status of the neutral, characteristics of the machines, levels and duration of the fault currents, etc. While doing the hv test the steps to be followed are as below.
Megger guide to electrical insulation testing pdf instrumart. It is important when operating on medium voltage equipment that we follow the safety rules and operating regulations in order to be safe. Testing insulated conductors use a proximity tester for a first test should not be used as the only test if no voltage indicated wearing ppe, expose conductor for testing verify 0 volts with contact meter voltage indicated with proximity tester verify proper circuit is locked out recheck source for induced voltage using a high. P53 high voltage isolation and access procedures prior to gaining access to hv cable. Standard for acceptance testing specifications for electrical. Typical factory test procedures for medium voltage products. Vlf hipots are also widely used for testing newly installed andor repaired cable before reenergizing to insure the cable is sound and for testing critical cable runs. Ieee std 400 provides additional information on dc testing and evaluation of the insulation of shielded power cable systems c. The current method of testing circuit breakers 05152011one of the most critical devices on any electricity network is the circuit breaker which can be described as the silent sentinel, standing guard over the network and only being called into action when. This technical article provides general guidelines for high potential hi pot dc testing of mv power cables. Electrical utility field testing for mediumvoltage cables this document outlines the various methods for field testing mediumvoltage cable either during or after installation. Guidelines for high potential hipot dc testing of medium.
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. Sometimes the drop in insulation resistance is sudden, as when equipment. When the various layers are removed, cuts should extend only partially. Manual installation commissioning environment and recycling. The values associated with the testing methods shall be in accordance with the applicable table 100. Perform a shieldcontinuity test on each power cable by ohmmeter method. Euromold provides a complete range of accessories for underground cables. The cable tests described below are to be carried out after. It is important to recognize that many factors must be considered to properly characterize the test results obtained from any cable testing program. Hundreds of standards including cable testing standards. Mediumhigh voltage cable preparation it is necessary to begin with a good cable end. Vlf systems are advantageous in that they can be manufactured to be small and lightweight.
Various cable testing practices are covered in the following documentation. If the tan delta numbers indicate good cable insulation, the test voltage is raised up to 1. A typical 15 kv medium voltage cable in usa has an insulation thickness of 0. The complete guide to electrical insulation testing. Calculation procedure 19 installation in cable tray 20 rollers and sheaves 20. Full clockwise rotation to min minimum connect the high voltage test cable to the ac out u post and the ground test cable is connected to ground g post as shown in illustration b. Rated 5 kv and above with high direct current voltage. A stitch in time 5 once started, the different enemies tend to aid each other, permitting excessive current through the insulation. 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. Dc leakage currents tell little about the cable quality. 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. Acceptance and maintenance testing of medium voltage power. Visual inspection is recommended for all incoming material as cable could be damaged during shipment and delivery.
In accordance with icea, iec, ieee and other power cable consensus standards, testing can be performed by means of direct current, power frequency. Maintenance free unit offering a life expectation of over 30 years. Vlf cable test voltages and time durations are set by ieee standard 400. Medium high voltage cable preparation it is necessary to begin with a good cable end. Single and three core medium voltage cables according to international standard iec 60502 1. Insulation resistance testing is a nondestructive test procedure. High voltage cable splicing and cable termination techniques final, by david e. High voltage test is done by applying 80% of factorytested voltage. The choice of testing techniques and procedures for medium voltage cables is now.
Example of asbestos paper insulation wrap on highvoltage cable inside an underground cable vault. If there any formula for calculating leakage current, cable rated voltage 8. Electrical utility field testing for mediumvoltage cables. Perform an insulationresistance test utilizing a megohmmeter with a voltage output of at least 2500 volts.
Medium voltage operation mv drives and soft starters are temporarily installed in the mv test bay and operated on an mv dynamometer. For other cable on a reel, insulation resistance testing can be performed provided the sealing caps are removed. Medium voltage products technical guide protection criteria. For doing r phase the other phases are shorted and earthed. Testing of high voltage cables manual horizon power. This publication is a collection of items of general information related to the subject of power cable. The manufacturers and nonnuclearpower users of medium voltage cable have since recognized that cables manufactured. Medium voltage cables used in nuclear power plants were expected to have very long lives, at least the 40 years of the initial licensed period. Acceptable procedures for conducting hipot testing, although varying slightly in technique, have been standardized as either a withstand test or a timeleaking current test.
Several builtin interlocks and safety features are provided. Tests using multivoltage megger insulation testers 42. The dielectric voltagewithstand test is commonly known as the hipot test. The choice of testing techniques and procedures for medium voltage cables is now well defined and enables the implementation of. Request startup documentation from the startup engineer level 3 testing acceptance testing documentation is often accepted as level 3 testing in this situation as long as there isnt a control system involved see medium voltage and complex electrical systems use the startup documentation, submittal, and opr to. This paper covers general safe operations on medium voltage equipment and looks at the aspects of switching, isolating, testing and earthing, as well as various types of medium voltage testers and their usage. The following sections of the ansineta standard for acceptance testing specifications for. Performed by stressing the insulation of the product far beyond what it would encounter during normal use. When comparing this figure to power frequency ac or 0. The procedure to test these cables is outlined below. Commissioning tests for hv cables up to 33kv swp ergon energy.
The cable is fed from the bottom of the reel so that its curvature is continuous with no reversed bends. A new set of well conceived testing standards has been developed in response to changes in cable technology in recent years. The test measures the insulation resistance between the phases andor between phase and ground. From a definition point of view ax1 is a primary encapsulated and air insulated switchgear. Applying voltage to the equipment and connecting to a test motor in the mv test facility. High quality tank welding, leakage rate of less than 0. 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 voltage testing for new and aged xlpe cables. Typical factory test procedures for medium voltage products 3. Compare bolted connection resistances to values of similar connections. Netas 2010 outstanding acheievement award honoring netas most valuable asset. Instructions for installation, operation, and maintenance.