Generator Testing - Offered by Industrial Tests, Inc
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With more than 35 years experience in restoration and repair of critical electrical systems due to equipment failure, Industrial Tests is the trusted service provider you can depend on. Industrial Tests offers facility maintenance customers sophisticated “power tools” and test equipment to maintain electric systems. We may also be able to provide you with electric facility maintenance and repair services that matches your scheduling needs.
Industrial Tests provides engineering solutions for electrical apparatus condition and assessment of high voltage substation and generator plants. Electrical measurement condition monitoring and chemical analytical methods provide data that is analyzed by generator experts. Industrial Tests,Inc. is a full member of the National Electrical Testing Association.  
Generator Tests Performed:
Partial Discharge Testing
Industrial Tests, a leader in diagnostic measurements and knowledge services for the Power Plant industry, is proud to offer an innovative approach to test generators, motors, exciters, isophase bus, switchgear, transformers, and power cables –  Partial Discharge Testing or PD Testing,  the newest addition to Industrial Tests consulting services is a non-invasive on-line surveillance technique that can detect and identify defects in a motor or generator and associated electrical systems while each power system remains in service.  For more information on PD Testing, email

PD Testing techniques can provide critical information useful for developing targeted maintenance strategies for power systems, and can also identify equipment that does not need attention or repair. This is a passive, totally non-invasive measurement technique, with no applied signal. Data is collected without affecting operations, and the process is inherently safe. PD Testing can provide valuable maintenance recommendations on the very first test. The testing equipment is very sensitive and measurement accuracy is traceable to NIST standards. PD Testing presents an opportunity for companies to dramatically improve their condition assessment and maintenance programs. PD Testing can save money and time by identifying specific areas that require maintenance, repair, or replacement allowing strategic, proactive, planned decisions to be made well in advance of an upcoming scheduled outage. 
 On-line Stator Winding Partial discharge
Industrial Tests can visit on-site to down load data, or make spot measurements using our instrumentation. An assessment of data will be provided on an annual basis.
On-line Generator condition monitor
Many generators have a detector to identify particulate products of overheating. Industrial Tests will visit on a 3-monthly schedule to check functionality.
Corona Detection Camera and Powerscan™
Corona probe testing can pinpoint partial discharge location in each slot.   It is useful in determining the precise location of partial discharge in a particular coil.   The probe can also be used as a testing tool to measure levels of partial discharge.
DC Insulation resistance (IR) and Polarization Index(PI)
The IR test is useful as a check that the stator will not to be at risk from AC testing at the lower gas pressure following degassing. At the end of the outage it is a simple indicator of adequate dryness and absence of foreign bodies.
Dielectric Dishcharge (DD) and Step Voltage (SV)
The Dielectric Discharge Test gives an indication of the amount of absorbed dirt and moisture.  Another extremely useful test is an automated step voltage test.   The step voltage test is based on the principle that an ideal insulator will produce identical resistance readings at all voltages.  An insulator which is being stressed will show lower resistance values as voltages are increased.   
AC Power factor and capacitance
After satisfactorily completing the DC test a main diagnostic set of tests can be performed. The next step of testing is performing AC tests at high voltage and involving the measurement of power factor (or loss tangent), capacitance and partial discharge. These tests provide a measure of contamination, moisture de-bonding and void growth within the insulation and detect contamination on the end-winding.
AC Partial discharge
The PD characteristic can be used to identify the type of defect, and so adds an additional diagnostic tool to the power factor tip up. If end covers are removed and end-winding discharge is indicated, these areas can be scanned when the winding is energized using ultra-Sonics and a daylight camera to locate the sites.
Online test for Rotor winding integrity using Generatortech™
Rotor winding insulation inter-turn and earth faults are detected using proprietary software developed by Generatortech. The test is very sensitive and will give an indication of the early stages of an inter-turn fault.
Generator Excitation testing
AVRs are inspected off load plus a test sequence involving three- phase injection, with DC sequence and operating load tests during recommissioning of the unit.
Protective Relays
Generator relays such as the SEL 300G, GE489 or Beckwith M3425 field tested and checked for calibration with three phase relay test set.
Thermocouples, RTDs, and Insulated bearings are checked with a low voltage DC test for continuity and resistance to earth.
Outage test for ELCID and Ring Flux test
The major additional test in a major outage checking for core damage causing overheating.
Winding/ Copper Resistance
Industrial Tests, Inc. can measure the low resistance of the field and stator windings and test the pole balance of the generator field when accessible.  Each phase of the stator winding is measured using a 10 amp or 25 amp micro ohmmeter. 
Visual Inspection
A visual inspection is one of the most valuable processes and should only be performed by an experienced engineer. The inspection is done by performing a minor outage confined to the endwinding areas. Removing the rotor and exposing the slot wedges and core teeth will allow for a more extensive visual inspection. The wedge tightness can also be checked.
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