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What kind of AC load uses the energy needed to magnetize a motor or a transformer winding?
Wiki User
∙ 11y ago
inductive load
Wiki User
∙ 11y ago
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Why doesn't the primary winding on a transformer have a neutral?
In a three phase transformer, the primary winding is often configured in a Delta. The delta winding configuration does not use a neutral. The secondary winding is often in a Wye configuration, which does have a neutral. The Delta configuration is typically used for transmitting power to various locations, and thee phase loads where a neutral is not needed. The Wye configuration is typically used to distribute power in a facility where there are single phase loads that need a neutral. There are other reasons to use either Wye or Delta, such as grounding issues, but I think the short answer is probably what you're looking for (I hope). Hope this helps! Dave
Why the open and short ckt test of transformer is needed?
The open/short-circuit test on a transformer isn't 'needed'. It's only used if you want to find out the efficiency of a transformer.
What will happen to the transformer if DC voltage is applied to the primary winding?
DC current will not pass through a transformer, in the sense that a DC current on the primary will not produce a DC output from the secondary. A constant DC current will not produce any output from the secondary but there may be transient effects as the DC current is connected or disconnected (in which case, it's really an AC current, isn't it?) More about this below because I don't think that's really the question. If you pass DC current through either winding of a transformer, two things will happen. First, you will heat up the transformer and, if you have enough DC current, you will burn it out. Second, you will induce a magnetic field in the core. The more current, the closer the core gets to "saturation" or the maximum field it can support. This is important if there is both DC and AC current present because the more DC field in the core, the less core capacity is available to "transform" AC current. As the core operates closer to saturation, the AC waveform will be distorted and some of the AC power will be lost to heating the transformer. For example, if the primary of a transformer is connected to an AC source, and a DC source is connected to the secondary, then the primary current drawn by the transformer will increase, possibly enough to destroy the transformer. There are special transformers, called magnetic amplifiers, which take advantage of this effect to use a DC current to modulate an AC current. There are transient effects of DC currents in a transformer winding. As the DC current magnetizes the core, energy is stored. When the DC current is disconnected, this stored energy wants to leave the core. It can do this by inducing a voltage in either of the windings. If both windings are open circuit, this voltage can be very high. So you may see a spark jump when the DC voltage is disconnected. In a large transformer, this discharge may break down the transformer insulation and damage it. Some switching power supplies take advantage of this effect in which case the transformer is wound slightly differently and called a "coupled inductor."
Why a full wave rectifier is preferred over a half wave rectifier?
The a.c. component, or ripple, produced by the 4-diode (full wave) bridge rectifier is the same as that produced by the 2-diode full wave rectifier. The bridge is connected across the secondary winding of a transformer. The 2 diodes of the other type of full wave rectifier are each connected to one end of a winding, but that winding requires a center tap. For any desired value of d.c. after rectification, the a.c. voltage of the 2-diode rectifier winding has to be twice that of the winding required for the bridge.
What happen if single phase supply give to two phase and one phase is earthed of three phase transformer?
Nothing good. This could lead to core saturation (core is sized for flux flowing from three phases 120 degrees out from eachother) which would cause large currents to flow into the transformer. Depending on the primary and secondary connection type (Wye or delta), voltage readings would be strange. To give real specific answers, more information is needed (core type, autotransformer, three winding, voltage of primary and secondary, winding connections, phase relationship (such as Ydn), etc.).
What is the function of the primary current when the secondary winding of the transformer is open?
When the secondary of a transformer is opened, there is no longer any load on the transformer. There will be some current flowing in the primary winding, which is needed to induce the voltage in the secondary. This primary current is referred to as the "no load" current, and is indicative of the core losses in the transformer.
What are the three basic parts of transformer?
core - air, iron, ferrite, etc.windings - one or more coils wound around the core.bobbin - insulating structure used to hold the windings. optional, not needed in every type of transformer. in some types of transformer the windings are prewound on the bobbin then the core is inserted into the bobbin.
What transformer is needed to convert 220volts to 110 volts?
Yes, transformers which operate on 110 - 120 Volts exist. This question is probably incomplete as it only mentions one voltage: it could be for the primary or the secondary or for a single-winding auto-transformer. The missing information cannot be guessed...
Why does a transformer need continuous rise and fall of current to induce a current into the secondary windings?
That is how inductance works. The rise is needed to charge the primary. When the field collapses, that is when the current is induced in the secondary winding(s).
Why doesn't the primary winding on a transformer have a neutral?
In a three phase transformer, the primary winding is often configured in a Delta. The delta winding configuration does not use a neutral. The secondary winding is often in a Wye configuration, which does have a neutral. The Delta configuration is typically used for transmitting power to various locations, and thee phase loads where a neutral is not needed. The Wye configuration is typically used to distribute power in a facility where there are single phase loads that need a neutral. There are other reasons to use either Wye or Delta, such as grounding issues, but I think the short answer is probably what you're looking for (I hope). Hope this helps! Dave
Magnetic inrush current in power transformer?
When a transformer is initially connected to a source of AC voltage, there may be a substantial surge of current through the primary winding called inrush current. Inrush current can be up to ten times higher than the continuously needed current because there is low initial resistance.
Why the open and short ckt test of transformer is needed?
The open/short-circuit test on a transformer isn't 'needed'. It's only used if you want to find out the efficiency of a transformer.
What is transformer polarity?
'Polarity' describes the sense (direction) in which the voltage (not current!) induced into secondary winding is acting, relative to the sense in which the voltage applied to the primary winding is acting.In North America, a transformer's high-voltage winding terminals are identified by the letter H, and the low-voltage winding terminals by the letter X. In the case of a two-winding transformer, the pair of high-voltage terminals are marked H1 - H2, and the pair of low-voltage terminals are marked X1 - X2.When the potential of HV terminal H1 'goes positive' (i.e. during the first half-cycle of AC), if LV terminal X1 also goes positive at the same time, then the transformer is an 'additive polarity' transformer. On the other hand, if terminal X2 goes positive at the same time as H1, then the transformer is a 'subtractive polarity' transformer.Knowing the polarity of a transformer is very important if you intend to operate transformers in parallel with each other (there are other factors, too, of course), in the same way as it is important to know the polarity of a battery before you can connect it in parallel with another battery.
What will happen to the transformer if DC voltage is applied to the primary winding?
DC current will not pass through a transformer, in the sense that a DC current on the primary will not produce a DC output from the secondary. A constant DC current will not produce any output from the secondary but there may be transient effects as the DC current is connected or disconnected (in which case, it's really an AC current, isn't it?) More about this below because I don't think that's really the question. If you pass DC current through either winding of a transformer, two things will happen. First, you will heat up the transformer and, if you have enough DC current, you will burn it out. Second, you will induce a magnetic field in the core. The more current, the closer the core gets to "saturation" or the maximum field it can support. This is important if there is both DC and AC current present because the more DC field in the core, the less core capacity is available to "transform" AC current. As the core operates closer to saturation, the AC waveform will be distorted and some of the AC power will be lost to heating the transformer. For example, if the primary of a transformer is connected to an AC source, and a DC source is connected to the secondary, then the primary current drawn by the transformer will increase, possibly enough to destroy the transformer. There are special transformers, called magnetic amplifiers, which take advantage of this effect to use a DC current to modulate an AC current. There are transient effects of DC currents in a transformer winding. As the DC current magnetizes the core, energy is stored. When the DC current is disconnected, this stored energy wants to leave the core. It can do this by inducing a voltage in either of the windings. If both windings are open circuit, this voltage can be very high. So you may see a spark jump when the DC voltage is disconnected. In a large transformer, this discharge may break down the transformer insulation and damage it. Some switching power supplies take advantage of this effect in which case the transformer is wound slightly differently and called a "coupled inductor."
How we select a transformer by vectorgroup?
A Vector group is the International Electrotechnical Commission (IEC) method of categorizing the primary and secondary winding configurations of three-phase transformers. Within a polyphase system power transformer it indicates the windings configurations and the difference in phase angle between them. The phase windings of a polyphase transformer can be connected together internally in different configurations, depending on what characteristics are needed from the transformer. For example, in a three-phase power system, it may be necessary to connect a three-wire system to a four-wire system, or vice versa. Because of this, transformers are manufactured with a variety of winding configurations to meet these requirements. Different combinations of winding connections will result in different phase angles between the voltages on the windings. This limits the types of transformers that can be connected between two systems, because mismatching phase angles can result in circulating current and other system disturbances. Symbol designation The vector group provides a simple way of indicating how the internal connections of a particular transformer are arranged. In the system adopted by the IEC, the vector group is indicated by a code consisting of two or three letters, followed by one or two digits. The letters indicate the winding configuration as follows: * D: Delta winding, also called a mesh winding. Each phase terminal connects to two windings, so the windings form a triangular configuration with the terminals on the points of the triangle. * Y: Wye winding, also called a star winding. Each phase terminal connects to one end of a winding, and the other end of each winding connects to the other two at a central point, so that the configuration resembles a capital letter Y. The central point may or may not be connected outside of the transformer. * Z: Zigzag winding, or interconnected star winding. Basically similar to a star winding, but the windings are arranged so that the three legs are "bent" when the phase diagram is drawn. Zigzag-wound transformers have special characteristics and are not commonly used where these characteristics are not needed. * III: Independent windings. The three windings are not interconnected inside the transformer at all, and must be connected externally. In the IEC vector group code, each letter stands for one set of windings. The HV winding is designated with a capital letter, followed by medium or low voltage windings designated with a lowercase letter. The digits following the letter codes indicate the difference in phase angle between the windings, with HV winding is taken as a reference. The number is in units of 30 degrees. For example, a transformer with a vector group of Dy1 has a delta-connected HV winding and a wye-connected LV winding. The phase angle of the LV winding leads the HV by 30 degrees. The point of confusion is in how to use this notation in a step-up transformer. As the IEC60076-1 standard has stated, the notation is HV-LV in sequence. For example, a step-up transformer with a delta-connected primary, and star-connected secondary, is not written as 'dY11', but 'Yd11'. The 11 indicates the LV phase lags 30 degree behind the HV side. Transformers built to ANSI standards usually do not have the vector group shown on their nameplate and instead a vector diagram is given to show the relationship between the primary and other windings.
How many watt transformer is needed for 2.5 amp motor?
Need to know the voltage of the motor and primary voltage of the transformer.
Why a full wave rectifier is preferred over a half wave rectifier?
The a.c. component, or ripple, produced by the 4-diode (full wave) bridge rectifier is the same as that produced by the 2-diode full wave rectifier. The bridge is connected across the secondary winding of a transformer. The 2 diodes of the other type of full wave rectifier are each connected to one end of a winding, but that winding requires a center tap. For any desired value of d.c. after rectification, the a.c. voltage of the 2-diode rectifier winding has to be twice that of the winding required for the bridge.
