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normally delta connection wired in 3 phase induction motor. during starting wiring is in Star and after running normal speed changeover to delta .beacause starting time its phase voltage equals less root3 times of line voltage ,line current and phase current equals.
in Delta phase voltage and line voltage equals, and phase current equals root3 times line current
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Why does delta connection have no neutral connection?
Lets compare between a star and delta connection in 3-phase power types. In a star connection, there are 6 connections (A1, B1 and C1 being the outer arms of the 3 armed star and at the centre, A2, B2 and C2). The center is called the neutral or star point which carries out the any unbalanced current loads through its connection. That is why if you lose out the neutral point in a star connection, there will be an overflow of current through to the loads. The loads also take in more current, generating much more power and could damage the appliance you are using and the components the line current is connected to, since excess heat and overworking may result.In a delta connection, the connection has only 3 and on a piece of paper it is sketched as the connections being joined arm to arm. One side is A phase, B phase and C phase. Getting to the point, a Delta connection does not have a earth wire because the live voltage is always the same throughout the connection. Since phase and line voltage are the same and constants. It also means the line current will change without affecting other components within the circuit. Balanced Delta connected circuits or loads can only have their power supply sourced from a star connection and a balanced Star load can only have their voltage supply come from a delta connection.Another AnswerWith a delta connection, the phasor sum of the three line currents is zero, whether the load is balanced or unbalanced, so no neutral is necessary.
Why use link in star contactor?
The link in the star contactor is used to form the star point of three of the motor leads. On most star wound motors the star point is inside the motor windings. On a motor that can be used for star delta starting it is a six wire motor. The star point winding depends on the contactor to tie the coil ends together externally in the control panel of the star delta starter.
How does 3 wire and 4 wire system differs?
If you are referring to a.c. three-phase systems, then a three-wire system is associated with a delta-connected system, while a four-wire system is associated with a star, or wye, system. The conductors being three line conductors and a neutral conductor.
Why you use the star delta connection?
Advantage:Star Connection:In a star connection, phase voltage Vph = VL/ (3)1/2. Since the induced emf in the primary winding of an alternator is directly proportional to the number of turns, a star connected alternator will require less number of turns than a delta connected alternator for the same voltage.For the same line voltage, a star connected alternator requires less insulation than a delta connected alternator. Due to the above reasons three phase alternators are generally star connected.In star connection, we get 3-phase and 4-wire system. This permits the use of two voltages (phase voltages as well as line voltages). Single phase loads can be connected between any one lie and neutral wire while the 3-phase loads can be put across the three lines. Such a flexibility is not available in delta connectionIn star connection, the neutral point can be earthed. Such a measure offers many advantages. For example, in case of line to earth fault (L-G fault), the insulators have to bear 1/31/2 (57.7%) times the line voltage. Earthing of neutral also permits the use of protective devices (relays) to protect the system in the case of ground faults
What is a floating neutral wire?
a loose connection of a neutral wire
How do you wire a three phase motor with two speed?
Star and delta connection
Why delta connections used in overhead transmission lines?
There are essentially 2 types of connections for a 3 phase AC transmission lines Star and Delta , Star is a 4 wire connection with each phase supplying potential with respect to a common ground wire , while delta is 3 wire connection with any single phase at one given time acting as a ground , for transmission reducing one wire makes a lot of cost difference hence it is favored
Why is star connection used in a three phase transformer?
The power of all three phases can be transmitted on three conductors.A star connection, as opposed to a delta, provides a grounding reference. Also, for ground faults on the secondary (assuming no delta third winding, or source third winding) will be a direct ratio similar to phase faults, instead of 57%. Another reason is to avoid the inherent phase shift involved in a delta/star configured transformer.Another AnswerA 'star-connected' secondary is the standard European connection for a three-phase distribution transformer, as it provides a line voltage of 400 V together with a phase voltage (i.e. line to neutral) of 230 V.
Which connection is best suit for 3 phase 4 wire service and why?
STAR connection is best suit for 3 phase 4 wire seviceas there is a neautral wire is there in this connection
Why most generation firm uses delta connection in the secondary side?
Many industrial installation use delta a secondary connection because it reduces the cost associated with a fourth wire.
How can you terminate a 3 wire wye motor to a 3 phase delta connection?
To terminate a 3 wire wye motor to a 3 phase delta connection you need a 3 phase transformer to convert from delta to wye. Do not lift the common neutral connections inside the motor and rewire for delta, because the voltages will be wrong.
What is the difference between star delta and wye delta?
With a delta connection, picture a triangle. Each side of the triangle is a transformer or motor winding. Call the 3 corners of the triangle A, B, and C. There are only 3 wires except for a safety ground, which has no connection to, nor is any part of, the power transmission service lines.but for the star connection take our triangle above and use your wire cutters (literally) to cut the triangle apart at the corners. rearrange the three sides (transformer or motor windings) to form a Y. Where the three sides join in the centre, connect a fourth wire. Call this wire "neutral". Call the three ends A, B, and C. Connect the 3 supply service lines to A, B, and C.
What is a star star connection used for?
A connection is one or the other, star or delta in a three-phase system. Delta has the three loads connected between the live lines, while star has the loads connected from the live wires to a neutral point. In the power supply industry delta connections are normally used at high voltage because the circuits are three-phase 3-wire, with equal currents in all three phases. At low voltage (below 1000 v) the circuits are usually three-phase 4-wire using a star-connected transformer secondary, which allows a lot of separate single-phase loads to be supplied, each one between one of the live lines and the 4th neutral wire. That is how power is supplied to a group of houses.
Why does delta connection have no neutral connection?
Lets compare between a star and delta connection in 3-phase power types. In a star connection, there are 6 connections (A1, B1 and C1 being the outer arms of the 3 armed star and at the centre, A2, B2 and C2). The center is called the neutral or star point which carries out the any unbalanced current loads through its connection. That is why if you lose out the neutral point in a star connection, there will be an overflow of current through to the loads. The loads also take in more current, generating much more power and could damage the appliance you are using and the components the line current is connected to, since excess heat and overworking may result.In a delta connection, the connection has only 3 and on a piece of paper it is sketched as the connections being joined arm to arm. One side is A phase, B phase and C phase. Getting to the point, a Delta connection does not have a earth wire because the live voltage is always the same throughout the connection. Since phase and line voltage are the same and constants. It also means the line current will change without affecting other components within the circuit. Balanced Delta connected circuits or loads can only have their power supply sourced from a star connection and a balanced Star load can only have their voltage supply come from a delta connection.Another AnswerWith a delta connection, the phasor sum of the three line currents is zero, whether the load is balanced or unbalanced, so no neutral is necessary.
How can you wire a 6-pole isolator to disconnect a 6-wire star delta motor away from the mcc and near to the motor?
There is no need to place a 6 pole disconnect to isolate the motor in the field. The motor's leads at the motor's terminal box have to be wired for a delta connection. The star delta contactor in the MCC only has three wires on its output. Six wires do not have to be taken directly to the motor. The voltage is reduced at the start of the circuit when the starter in in the star configuration. From the star configuration it changes to the delta configuration. So as you can see only a three pole isolation switch is needed in the field to isolate the motor from its supply.
Why you use delta star transformer instead of star star transformer in a consumer plant?
Generally speaking high-voltage three-phase systems are three-wire systems comprising three line conductors, so the high-voltage primary of the transformer is delta-connected (a delta connection has only three terminals, to which the three line conductors are connected). European low-voltage three-phase systems are four-wire systems, comprising three line conductors and a neutral conductor. To obtain this, the transformer's secondary must be star (wye) connected, with its earthed star point providing the neutral.
What is the voltage-to-ground on a 4160 V delta circuit?
There should be no voltage to ground on a delta system. That is the reason that these types of systems have to have a set of grounding lights to warn when the system inadvertently grounds. A delta system is a three wire connection, no neutral. A voltage to ground is only available on a three phase four wire (star or wye) connection system. The fourth wire being a neutral which is grounded thereby giving a voltage from each leg to neutral.
