ieee wg c57.139 nashville, march 13, 2012 application...
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IEEE WG C57.139Nashville, March 13, 2012
APPLICATION OF DUVAL TRIANGLES 2TO DGA IN LTCs
Michel Duval
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Normal operation of LTCs may involve:
-arc-breaking-in-oil between contacts, producing arcing gases D1.-switching of selectors and valves, also producing sparking discharges D1.-current dissipation in resistors, increasing their temperature and producing hot spot gases T3, T2 or T1.-combinations of the above, producing mixtures of the corresponding gases.
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Faulty operation of LTCs may involve:
-an increase in the resistance and temperature of contacts, with the production of hot spots T3 and T2, and coking on contacts, through carbonization of oil.
-abnormal arcing D2 or D1 on metallic parts of the LTC.
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Examples of LTC failures:(heavy coking in a ABB UZC)
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Examples of LTC failures:(heavy coking in a Federal Pioneer TC546)
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Examples of LTC failures:(moderate coking in a GE LR83)
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Examples of LTC failures:(arcing/short-circuit in a GE LR83)
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Examples of LTC failures:(arcing/short-circuit in a GE LR65)
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To be able to distinguish between normal and faulty operation of LTCs:
-gases formed as a result of normal operation should be identified as precisely as possible under different power operating conditions.
-deviation from normal operation will indicate faulty operation.
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Mostly arcing gases are formed during normal operation of a large majority of LTCs, such as:
-LTCs of the reactive-type in oil or vacuum from:
-Westinghouse: UN, UR, UV series, UTS, UTN, UTT.-Cooper, McGrawEdison: series 394, 396, 494, 550, 995, 996.-General Electric: LR and LRT series.-Reinhausen: RM series.-Allis Chalmers, Siemens: TLH series.-Federal Pacific: TC series.-Ferranti Packard: RT series.
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-also, in LTCs of the resistive-type in oil or vacuum from:
-ABB: UB, UC, UZ series.-Reinhausen: OilTaps C, R, V, Y.-Westinghouse: UTH.-Hyundai: RS series.
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Duval Triangle 2 can be used for all these types of LTCs, with:
-arcing gases D1 appearing on the left side of the Triangle,
-hot spot gases T3, T2 and T1 on the right side.
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The Duval Triangle 2 for LTCs (inspected cases)
Inspected cases of: : Normal operation; : Severe coking; : Light coking; :
“Heating”; : Strong arcing D2; : Arcing D1
Fault zones:
N = normal operationT3 = Thermal faults T > 700°CT2 = Thermal faults 300 < T < 700°CX3 = Fault T3/T2 in progressX3 = abnormal arcing D2D1 = abnormal arcing D1
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HQ Data - All ABB
Ref. for all HQ data: M.Foata
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HQ Data – ABB In-tank cylinder
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HQ Data – ABB Selector switch
UZE change-over selector problem
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Altalink UZCRT
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HQ Data - GE LR83
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HQ Data – Ferranti Packard
Model known to be susceptible to coking in the inverter switch?
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HQ Data – Westinghouse URS
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HQ data - OilTaps V
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OilTaps R
The use of methane in addition to acetylene and ethyleneindicates some normal overheating T1 of the resistorsduring the operation of these LTCs.
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Triangle 2 applied to large databases by J.Dukarm
Siemens Westinghouse
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Triangle 2 applied to large databases by J.Dukarm
McGraw Edison Cooper
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Other types of normal operation
-Some resistive LTCs such as OilTaps Y and M and VacuTaps VV operate normally in either zone N or zone T3 or zone T2, depending on operating conditions.
-The use of methane in addition to acetylene and ethylene allows to distinguish between faulty and normal operation in such LTCs.
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HQ data - OilTaps D:
3 phases - Y 1 phase - ∆ Normal operationof resistors
Faulty operation
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During high power tests, normal (in blue) and faultyoperation (in red) of resistors.
VacuTaps VV:
Ref: R.Frotscher, CIGRE
In service, normal operation of selectors
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Ref: R.Frotscher (Orlando)
VacuTaps VR:Normal operation in zone T2 is probably due to operation of selectors and resistors.
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-A few other resistive LTCs such as OilTaps G and some UZBs of ABB (ref.John Pruente) operate normally in zone X3 (mixture of arc-breaking-in-oil and high-temperature operation of resistors), depending on operating conditions.
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HQ data - OilTaps G:OilTaps G are high-currents application models. Normal gases occur in zone X3 (mixture of arcing and hot spots).
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Different versions of Triangle 2 should therefore be used for some LTCs, indicating the normal zone(s) of operation depending on power operating conditions:
-Triangle 2a and 2b for OilTaps M-Y and VacuTaps VR-VV.
-Triangle 2c for OilTaps G and some UZBs.
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Finally, reactive LTCs of the vacuum-type:
-Arc-breaking activity occurs in the vacuum bottle only. Normal operation in the surrounding oil used for cooling the bottle does not involve sparking of selector or resistor heating.
-Triangle 1 should be used for these LTCs.
Overheating in oil suspectedRef: Paul Boman
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