search.noResults

search.searching

note.createNoteMessage

search.noResults

search.searching

orderForm.title

orderForm.productCode
orderForm.description
orderForm.quantity
orderForm.itemPrice
orderForm.price
orderForm.totalPrice
orderForm.deliveryDetails.billingAddress
orderForm.deliveryDetails.deliveryAddress
orderForm.noItems
FEAT RE FEA ATURE


TEST S STE


TEST SYSTEMS


ELECTRICAL TESTING – THE MISSING LINK IN MOTOR CONDITION MONITORING?


ELECTRI AL TESTING – of the poten ial failu em des. nm ni vital role thatm


channel and platformdevel pmentm nager electri motor condition monitoring at SKF, describes the vital role that modern electrical testing technologies play in predicting and preventing motor failures


h are i capable of detecti g al chael H rring ,


ng at SKF, describes the rn electrical testing tech M


onitoring the health of an electric motor should entail measurement


of both mechanical and electrical parameters in order to gain a comprehensive assessment of its


operating condition. Vibration signature analysis, thermography and even oil analysis will provide early indications of mechanical problems, but these are unlikely to reveal the onset of insulation failure, phase imbalances, torque


anomalies and the like, which will have a significant impact on motor performance and life expectancy.


Vibration measurement applied in motor conditio ,


n monitoring is commonly


programs and this alone, can identify approximately 70 per cent of the issues that might indicate pending failure, including problems with bearings, unbalanced loads and shaft


misalignment. Identifying the remaining 30 per cent of potential problems requires the use of electrical testing techniques, which fall into two broad categories: static tests, conducted on a motor when it’s not running, and


dynamic tests, conducted on the motor in service.


Some 80 per cent of the electrical


failures in motors begin with a failure of the thin insulation covering the motor winding, otherwise known as the turn- to-turn insulation. As this insulation degrades, the inrush of voltage during motor starting and stopping can cause arcing, further degrading the insulation and creating a conductive carbon path that will ultimately lead to a short-circuit and motor failure.


Static electrical testing of motors uses industry-accepted standards to identify these weaknesses within windings. Testing can be using specialist portable i


such as the SKF Static Motor Analyzer Baker AWA-IV, which removes operator


32 32 NOVEMBER 201 MBER 2016 | AU AUTOMA MAT ATION


nstrumentation automated the motor


variations in test sequencing. logies


play i predi ting and preventi gm tor fai ures error and inconsistencies arising from The test sequence is defined by the


measure winding resistance a AWA-IV software and is confi


gured to nd verify


Modern instrumentation and specialist services mean there really is no excuse for companies to leave the health of their critical motors to chance


Modern inst strumentation


and specialist services mean there really is no


critical motors to chan leave the health of the excuse for companies


rs to


ce ir


the dielectric strength of the insulation systemvia a series of specific test routines. One of these is the DC step voltage test, carried out over five or more incremental voltage steps, with the leakage current being plotted for each. Clean, dry insulation will show a linear plot, while insulation weakness or contamination is revealed by a non- linear increase in leakage. A surge test is also carried out to detect weak turn-to- turn and phase-to-phase insulation. Such weakness can be present without the motor displaying any signs of a problemduring operation, yet the winding resistance and megohmtests cannot identify such problems. Static test results are clear and unambiguous, and produce a specific result that requires little interpretation.


Static testing should also be performed annually on spare motors that are being held in stock. These motors often go unused for many years, yet are held solely for use when a production motor fails, or requires replacing. If the


condition of a stock motor is unknown prior to installation, there is a risk of failure during production.


Dynamic motor testing involves the measurement of the three phase voltages and currents which are then processed via a set of algorithms to assess the quality of the power supplied to the motor certain issues within the motor, such as cracked and broken rotor bars, and the condition of the driven load. It can be undertaken using instrumentation such as the SKF Dynamic Motor Analyzer - EXP4000, which is capable of multiple tests to determine power condition, motor health, motor load and energy


,


also able to monitor and percentage load


profile. As many as 40 parameters are monitored and recorded, including


voltage, current, frequency, torque, speed


the performance of . The EXP4000 is


inverter driven motor applications. Also worth noting is motor current


signature analysis, which, unlike dynamic analysis, measures only the phase currents to detect cracked and broken rotor bars and other mechanical issues. Also performed with the EXP4000, this test is normally carried out when the motor cannot be stopped to allow


voltage connections to be made, or in the case of high voltage motors, when low voltage secondary connections are not available in the panel to allow safe connection of the equipment.


While these tests are relatively easily conducted by trained in-house staff, the task can be outsourced to specialist providers such as SKF, fielding


engineering teams to undertake surveys of plant-wide industrial motor


installations. Comprehensive reports are made available to customers advising themof any actions or remedial work that may be required.


And for those sites that are either difficult to reach or pose a hazard to personnel, SKF can also offer remote dynamic motor monitoring based on the SKF Online Motor Analysis System– NetEP, which is capable of monitoring up to 32 motors, 24 hours a day, seven days a week, with data being sent directly to SKF for analysis. Multiple NetEP devices can be networked, to increase the number of motors being monitored. Modern instrumentation and specialist services mean there really is no excuse for companies to leave the health of their critical motors to chance.


www.skf.co.uk


SKF (U.K.) www


ww. /AUTOMATION AT /AUTOMATION T: 01582 490049 T: 01582 490049


com on cause ofm tor failu e. Yetm organisations perform only the very basic of electrical tests, which are incapable of detecting all of the potential failure modes. Michael Herring, channel and platform development manager, electric condi


After beari g problems, electrical faults are the most common cause of motor failure. Yet many organisations performonl electri al tests,


After bearing probl the very basic of electri al faults are them st


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56