ECM216 BUILDING SERVICES Bab 1.4 Star and Delta Connection
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EDITED BY AZUAN AHMAD FAUZI 2011803188 UITM PULAU PINANG MAC 2013 Star/Delta Connectio ns SINGLE PHASE & THREE , STAR – DELTA CONNECTION 1)THREE PHASE •In mostly countries , power is generated as a three phase 60 hertz voltage. •The term three phase means that there are three separate voltage waveforms produced by the alternator (generator that produced AC voltage) •For the alternator to produce the three phase , the internal winding of the alternator called the stator are wound 120° apart , the three voltages are 120°out of phase with each other. •The winding of the stator are connected to form one of the two basic three phase connections. •These connections are the delta and wye (star) 1)THREE PHASE (3 – Ø) •A combination of 3 single phase (1 – Ø) system. •3 separate but equal voltages , each out of phase by 120°. Advantages Of 3-ø System Over 1-ø System •For a given amount of poer transmitted trough a system the 3-Ø system requires conductors with a smaller cross-sectional area. This means asiving of copper 9or aluminium) and thus the original installation costs are less. •Two voltages are avalable i.e. 415V and 240V instead of 415V only. •3-Ø system motors are very robust, relatively cheap, generally smaller, have self- starting properties, provide a steadier output and require little maintenance compared with single-phase motors. Three Phase Connections •Three phase delta connection -All dissimilar ends of the coil are connected together V L = V P I L = √3 I P •Three phase star connection •All similar ends are connected together V L = √3 V P I L =I P •You can either have delta / star connected supply or Delta and Star connected load 3 Phase Distributi on Systems Relationship between star phase for 3-Ø, 4 wires The voltage between any line conductor and neutral life is called phase voltage (V ph )The voltage between any 2 lines conductor is called line voltage (V ln )Example if V ln = 415V Therefore The current between any line conductor neutral line is called phase current (I ph )The current between any two (2) lines conductor is called line current (I ln )ln 240 3 ph VV Vln 3 ph V Vln ph ph II Iz
