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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.
Is delta connection also called a star-star connection?
the delta has a higher voltage to ground on the B phase and is identified by the orange color for identification means so its easier to smoke equipment if not careful.hardly see delta connections anymore so old school and outdated. it just makes economic sense to use a star connection.On the above answer there should be no voltage to ground on a delta connection. All three phase coils are connected in series with each other and at no point in the delta are they grounded. Most of the commercial and industrial motor connections are connected delta. In installations where the motor inrush is above utility company specifications the Star- Delta connection is used. This limits the inrush current in the star configuration and then after a time delay connects the motor in a delta configuration. With delta systems the use of grounding lights are mandatory. These are used to detect if a phase grounds out. One phase and the motor can still be in operation, two grounds represent a short circuit and the system will trip.CommentThe second answer is not altogether correct... In the USA and Canada, it is common practise for one phase of the delta-connected secondary windings of a three-phase transformer bank, to have an earthed (grounded) centre tap. With each phase providing 240 V; the centre-tapped phase then provides a combination of 240 V line-to-line together with two 120-V line-to-neutral (earth) voltages which is the standard supply method for residences in North America. The point of common connection between the two remaining phases is termed the 'high leg' of that particular transformer connection, having a potential of 208 V with respect to earth (although this is not used). To summarise, this method provides a 240-V three-phase supply, combined with a single-phase 240/120-V supply, which is useful for small businesses (e.g. garages) which might need to operate three-phase motors.However, the second answer is perfectly true for the UK (and, possibly, elsewhere in Europe) where residences are supplied with just one voltage (230 V) -unlike North America- and delta-connected supplies are relatively unusual.
When is a motor in star or delta connection?
Star (or wye) connection is where each of the three phases has a fourth conductor, neutral, as its current return. Current flow in this configuration is phase to neutral, which is also grounded back at the distribution center. There will be five total connections, phase A, B, and C, neutral, and (protective earth) ground. Delta connection is where each of the three phases uses the prior phase as its current return. Current flow in this configuration is phase to phase, and there is no neutral, though there is still a ground. There will be four total connections, phase A, B, and C, and (protective earth) ground.
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.
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
Is home that is 220 volts single or 3 phase?
The nominal voltages for a home service utility in North America is single phase 120/240 volts. By special permission a home will be allowed a three phase connection. The only voltage close to that is 240 volts three phase delta. In Canada three phase delta is not used any more and is replaced with a three phase four wire system of 120/ 208 wye connection. The wye connection is used primarily in commercial, industrial and apartment building services.
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.
Is delta connection also called a star-star connection?
the delta has a higher voltage to ground on the B phase and is identified by the orange color for identification means so its easier to smoke equipment if not careful.hardly see delta connections anymore so old school and outdated. it just makes economic sense to use a star connection.On the above answer there should be no voltage to ground on a delta connection. All three phase coils are connected in series with each other and at no point in the delta are they grounded. Most of the commercial and industrial motor connections are connected delta. In installations where the motor inrush is above utility company specifications the Star- Delta connection is used. This limits the inrush current in the star configuration and then after a time delay connects the motor in a delta configuration. With delta systems the use of grounding lights are mandatory. These are used to detect if a phase grounds out. One phase and the motor can still be in operation, two grounds represent a short circuit and the system will trip.CommentThe second answer is not altogether correct... In the USA and Canada, it is common practise for one phase of the delta-connected secondary windings of a three-phase transformer bank, to have an earthed (grounded) centre tap. With each phase providing 240 V; the centre-tapped phase then provides a combination of 240 V line-to-line together with two 120-V line-to-neutral (earth) voltages which is the standard supply method for residences in North America. The point of common connection between the two remaining phases is termed the 'high leg' of that particular transformer connection, having a potential of 208 V with respect to earth (although this is not used). To summarise, this method provides a 240-V three-phase supply, combined with a single-phase 240/120-V supply, which is useful for small businesses (e.g. garages) which might need to operate three-phase motors.However, the second answer is perfectly true for the UK (and, possibly, elsewhere in Europe) where residences are supplied with just one voltage (230 V) -unlike North America- and delta-connected supplies are relatively unusual.
When is a motor in star or delta connection?
Star (or wye) connection is where each of the three phases has a fourth conductor, neutral, as its current return. Current flow in this configuration is phase to neutral, which is also grounded back at the distribution center. There will be five total connections, phase A, B, and C, neutral, and (protective earth) ground. Delta connection is where each of the three phases uses the prior phase as its current return. Current flow in this configuration is phase to phase, and there is no neutral, though there is still a ground. There will be four total connections, phase A, B, and C, and (protective earth) ground.
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.
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 Scott connection is used to convert three phase to two phase why cant you take two lines from three phase circuit?
In a two-phase connection, the phases are displaced by 90 degrees. Two lines (not 'phases') of a three-phase system will provide a single-phase supply, not a two-phase supply.
What is vector group of power transformer?
Hi first of all Vector group used to determine the PHASE shift of the TRANSFORMER as well as the PRIMARY and SECONDARY connection information. Let taken an example:- YNyn0d1 It means CAPITAL LETTERS indicates the primary side of winding detail's small letters for secondary side detail's DELTA CONNECTION Symbol D OR d is used and connection WYE used Y OR y for PRIMARY and SECONDARY. If WYE connection is their neutral always come so we used suffix N OR n. Now check PHASE angle Difference (PHASE ANGLE) see the last NUMERIC VALUE give correct information. Suppose we connect/compare two TRANSFORMER we first see its VECTOR GROUP if they matched then we do move to any connection. If any quarries fill-free to ask ajay.sahu099@gmail.com
What will cause my voltage to be higher on one phase and lower on the other?
If secondary side of the 3 phase transformer has any issue, it would result unbalanced voltage between phases. Other reason could be if the load on one phase is highly different than other phase, it also would result in unbalanced voltage.
Does open delta three phase transformer connection is used to convert three phase to two phase?
Two phase is not used anywhere. What you may be thinking is center tapped single phase (negative voltage at one terminal, neutral at 0, and positive at the other, all in phase so you can get 120 volts or 240 volts). Open delta would be used for three phase power. A single transformer can be used for single phase power. If you have limitted three phase power, and mostly single phase power needs, two transformers could be connected to provide both.Another AnswerAn 'open-delta' connection is used to provide a temporary three-phase supply to a load, from a three-phase transformer bank when one of the transformers has been removed due to failure. Linesmen can rewire the remaining two transformers in such a way that they still provide a three-phase supply, albeit at a reduced capacity.The open-delta connection can also be used to provide an initial (lower-cost) three-phase supply to a load when an increase in that load is anticipated at some time in the future. Adding a third-transformer then adds capacity to the existing transformer bank to match the predicted load increase.Two-phase systems are archaic and are unlikely to be encountered, these days. They are provided by alternators with two armature windings, displaced by 90 degrees.
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.
What is the use of 240 three phase delta?
A 240V three-phase delta system is commonly used for industrial and commercial applications to power motors, machinery, and equipment. It provides a higher voltage and power capacity compared to single-phase systems, making it suitable for heavy-duty operations. The delta configuration allows for a balance between power delivery and efficiency in three-phase systems.
