# HJ International Latin America, Inc. New vision regarding the real average load of distribution transformers in Latinamerican electrical grids. The situation.

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HJ International Latin America, Inc. New vision regarding the real average load of distribution transformers in Latinamerican electrical grids. The situation and the various paths to a soluction. Arguments based on IEEE C57.91-1995 (R2004)

HJ International Latin America, Inc. DEFINITION Demand curve RMS value in kVA Demand curve RMS value in kVA Cm = ---------------------------------------------------- Cm = ---------------------------------------------------- Nominal kVA value of the transformer Nominal kVA value of the transformer

HJ International Latin America, Inc. Regarding cycles of equivalent loads Note that the levels of overload and its duration are extracted from the proper curves of the real load and not from a standard…!! The accummulative concept of the loss of life… …day, month, year, all its life…

HJ International Latin America, Inc. Cycles of equivalent loads IEEE C57.91-1995 A transformer subjected to any one of these 3 cycles will exhibit the same performance in terms of energy While the RMS value of the load curve is below the nominal capacity of the transformer, the loss of life of the unit will be below the maximum permitted!!

HJ International Latin America, Inc. Diagram of temperatures

HJ International Latin America, Inc. Diagram of temperatures Direct measurement (thermocouples) Indirect measurement (resistance) Calculated (recomendations IEEE)

HJ International Latin America, Inc. Regarding the limits of load and temperature For operations above the nominal load Per IEEE C57.91 – Table 6 DISTRIBUTION TRANSFORMERS Temperature of the hot spot of the conductor: 200degC Short duration load (1/2 hour or less) 300% Top oil temperature: 120degC

HJ International Latin America, Inc. Regarding the limits of load and temperature For operation s above the nominal load Per IEEE C57.91 – Table 7 POWER TRANSFORMERS Temperature of the hot spot of the conductor: 180degC Short duration load (1/2 hour or less): 200% Top oil temperature: 110degC

HJ International Latin America, Inc. How a COMPLETE heat run should be done…

HJ International Latin America, Inc. DEFINITION: Factor regarding energerized medium load Annual invoicing in GWh Annual invoicing in GWh Fcme = -------------------------------------------------- Fcme = -------------------------------------------------- CITD * fp * 24 * 360 CITD * fp * 24 * 360 CITD: Installed capacity of Distribution Transformers, GVA CITD: Installed capacity of Distribution Transformers, GVA fp: Global power factor of the system fp: Global power factor of the system

HJ International Latin America, Inc. Average loadability of distribution transformers en the system (Example) The average sizes in the grid can be reduced in factors of 2 to 5!!

HJ International Latin America, Inc. For the losses and typically kVA cost that we found throughout the Latinamerican grids, the minimum operative cost for Cm to be between 50% and 75% of the nominal capacity of the distribution transformers. OPTIMUM SIZING

HJ International Latin America, Inc. THE COMPROMISE… WHERE WE ARE AT TODAY: WHERE WE HAVE TO BE: WHERE WE HAVE TO BE: Cm = 15 % Cm = 60 to 75 %

HJ International Latin America, Inc. Determination of the real demand Indirect measurements – CEMIG (Gemini) Administration of actives due to accummulated loss of life Compare the energy sold to the end users connected to the transformer to the energy the transformer has the capacity to deliver The real losses at the sight of installation are not accounted for.

HJ International Latin America, Inc. Direct measurement of energy delivered by the transformer The reading is compared to the energy sold to the end-users connected to the unit. If you compare the energy delivered by the transformer to a load profile, you will have a precise vision of the percentage of load. (Fuente: Redes de EEPPM)

HJ International Latin America, Inc. Other variants practiced currently Digital measurements Remote readings Remote signals (Fuente: Redes de EEPPM)

HJ International Latin America, Inc. Distribution of loads in a grid with optimum sizing CRITICAL ZONE WITH THE NEED TO ADEQUATE THERMO PROTECTIONCRITICAL ZONE WITH THE NEED TO ADEQUATE THERMO PROTECTION Example: Cm/Fd (0.60/0.65 =0.92)Example: Cm/Fd (0.60/0.65 =0.92)

HJ International Latin America, Inc. IS EVERYTHING CLEAR ?

HJ International Latin America, Inc. Factors to consider for the optimum sizing based on the consumption of energy REAL LOAD CURVE OR CHARACTERIZED AND 2 EQUIVALENT CYCLES.REAL LOAD CURVE OR CHARACTERIZED AND 2 EQUIVALENT CYCLES. DETERMINE THE RMS VALUE OF THE LOAD CURVE BASED ON THE ACTUAL CONSUMPTION.DETERMINE THE RMS VALUE OF THE LOAD CURVE BASED ON THE ACTUAL CONSUMPTION. LIMIT THE PROJECTION OF THE LOAD CURVE TO NO MORE THAN 5 YEARS.LIMIT THE PROJECTION OF THE LOAD CURVE TO NO MORE THAN 5 YEARS. DEFINED A UNTI SIZE THAT WILL REACH ITS OPTIMUM LOAD IN THE PROJECTED TIME.DEFINED A UNTI SIZE THAT WILL REACH ITS OPTIMUM LOAD IN THE PROJECTED TIME. SELECT AN APPROPRIATE THERMAL PROTECTIONSELECT AN APPROPRIATE THERMAL PROTECTION

HJ International Latin America, Inc. The type of transformer to be used in an optimized load environment To successfully operate distribution transformers at Cm levels between 50% and 75%, it is considered imperative that the protective devices used for the transformer, identify those levels of overload in magnitud and duration that cause loss of life above the maximum permitted.

HJ International Latin America, Inc. The areas of Over-Current Protection in a transformer...

The type of transformer to be utilized on optimum load environments and THE DEFINITIONS OF THE PROTECTION TO BE UTILIZED Emphasis on the control of the thermal compartment (following the load currents and the interior temperatures) Asset management of the grid Reduction of installation costs. Significant reductions of the global failure indices of transformers in the distribution system. Significant reductions of the global failure indices of transformers in the distribution system.

HJ International Latin America, Inc. The type of transformer to be utilized in an optimum load environment… Lighted signal or Information sent remotely Priviledging the need to interrupt dangerous load y even finding a better solution, we are installing CSP type transformers to provide an exact thermal protection and the capacity to interrupt at the site.

HJ International Latin America, Inc. The solution that the CSP transformer offers… SELF-PROTECTEDCONVENTIONAL CAJA NEGRA

HJ International Latin America, Inc. The solution that the CSP transformer offers… HV ARRESTER LV BREAKER FUSES LV ARRESTER

HJ International Latin America, Inc. The solution that the CSP transformer offers… SIGNAL LIGHT HANDLE AND EMERGENCY OVERLOAD LEVER

HJ International Latin America, Inc. The signal lamp as an element in providing an effective managemente of loads and assets along with an important role in balancing loads. LIGHT OFF STATUS OF GRID AND LOAD ARE NORMAL STATUS OF GRID AND LOAD ARE NORMAL LIGHT ON STATUS OF GRID AND LOAD ARE ABNORMAL STATUS OF GRID AND LOAD ARE ABNORMAL

HJ International Latin America, Inc. A practical application of the proposed model Case CFE – Veracruz District/Division Pilot grid used to size unit with an optimum Cm

HJ International Latin America, Inc. Summary of the pilot project achieved in the City of Veracruz - Mexico 1. GRID INSTALLED OPTIMIZED 2. Number of units 39 39 3. Average kVA 43.116.8 4. Total KVA 1,722.5655 5. Kwh./year 1,012,2831,012,283 6. Fcme 15.2%39% 7. Capitalized cost US\$65.8kUS\$34.4k units + losses 8. % Capitalized cost. 100%52.2% 9. Type of units ConventionalCSP

HJ International Latin America, Inc. Summary of the pilot project achieved in the City of Veracruz - Mexico

HJ International Latin America, Inc. Important points for a successful application COORDINATION OF PROTECTIVE DEVICES AND REAL EXERCISES OF OVERLOAD PROTECTION

When making an economic evaluation of a project using conventional vs CSP type transformers THE SIZE OF TRANSFORMER BEING COMPARED ARE DIFFERENT CONVENTIONAL kVA = X kVA = X/2

HJ International Latin America, Inc. The experience in Mexico was worth the effort… Letter from the Sub-Director of CFE indicating all the benefits achieved.

HJ International Latin America, Inc. END NATALIA Other recommendations: The case of transformers in Distribution Substations Primary and secondary distribution cables Orlando Giraldo – Sales and Operations Manager - HJ International Latin America orlandog@h-jenterprises.com – USA (636) 677 3421 – (Colombia) 57 1 478 4141 orlandog@h-jenterprises.com

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