power distribution - Siemens

TransformersNEMA TP1 Energy Efficiency StandardSingle Phase and Three PhaseTP1–Energy Efficient TransformersMost commercial and industrial facilitiesrequire several low-voltage transformersto decrease the voltage received fromthe utility to the voltages used by variousloads such as lighting, computers andother electrically operated equipment.Standard transformers convert approximately95% of the electricity receivedinto usable output voltage. Since thesetransformers are energized continually,even a small improvement in efficiencycan provide significant energy savings.These energy efficient transformers arespecifically designed to help save moneyon utility bills and reduce energy waste.Depending on the size of the transformer,a “NEMA TP1 compliant” transformer cansave $100-300 each year at an electricityrate of $0.075 cents per kWh. A typicallarge commercial facility will have 6-10 lowvoltage transformers, and thus can savebetween $600 and $3,000 per year.Basic Design CharacteristicsThe TP1 designs include the use of highergrade electrical steel and other featuresdesigned to lower flux density and reducelosses especially at average 35% loadingwhere the TP1 measurements apply.To meet TP1 the design engineer mustconsider both the “I square R” losses andthe core or iron loses. Simple de-ratingfrom a higher kVA will not satisfy the TP1standards as the efficiency level isdependent on the combination of core(no-load) losses and I2R (winding) losses.The core construction employs the use ofhigh quality non-aging electrical gradegrain-oriented silicon steel with highpermeability, low hysteresis and low eddycurrent losses. These characteristics arerequired to achieve the TP1 efficiencylevels. Core laminations must be tightlyassembled enabling magnetic fluxdensities to be kept well below thesaturation point.The core and coil designs must be lowloss type with minimum efficiencies perNEMA TP1 when operated at 35% offull load capacity. Efficiency shall betested in accordance with NEMA TP2(Standard test method for measuringthe energy consumption of distributiontransformers). The efficiency levels mustmeet the following minimums.SelectionTP1- Energy Efficient transformers:Single Phase Three PhasekVA Efficiency kVA Efficiency15 97.7% 15 97.0%25 98.0% 30 97.5%37.5 98.2% 45 97.7%50 98.3% 75 98.0%75 98.5% 112.5 98.2%100 98.6% 150 98.3%167 98.7% 225 98.5%250 98.8% 300 98.6%333 98.9% 500 98.7%750 98.8%7TRANSFORMERSNew Super Energy EfficientTransformers:TP1S, HM1S & HM2STP1S transformer designs surpass theNEMA TP1 standards for efficiency.These units are designed not to exceed115°C temperature rise above a 40°Cambient under full linear load and not toexceed 150°C rise under a non-linearload level of K13 (K20 for HMT units).Standard features of the TP1S, HM1S,HM2S units include:▪ Higher efficiency level with LinearLoad Efficiency: 25% less loss thanNEMA TP-1 from 35% to 65% load @75°C for sizes 15-750KVA▪ TP1S units are TP1 Rated efficiencyunder non-linear loads with a loadprofile of K13 at 50% loads @ 75°C▪ Noise levels are 3 dB lower thanNEMA ST-20▪ Standard 200% neutral▪ K13 rating on nameplate (K20 forHMT units)▪ Electrostatic shield▪ Ten year pro-rated warranty withstandard liability limitations same asSentron Harmonic Mitigation units7-14Siemens Power Distribution & Control, SPEEDFAX 2007-2008 Product Catalog