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Why line voltage at the secondary of transformer is above the required value?
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∙ 11y ago
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How do you know the primary or secondary side of a transformer?
The primary side is usually labelled 'H', the secondary is often labelled 'L'.Primary wiring will often be smaller, since the current carrying capacity doesn't have to be as high on the primary side.The best thing to do would be to check with the manufacturer. They should have documentation stating what is primary and secondary.CommentThe above answer only applies to step-down transformers. The simple answer is that the primary winding is the winding connected to the supply, whereas the secondarywinding is the winding connected to the load. These terms have nothing to do with voltage levels.
What is knee point voltage of current transformer?
10 % increase in voltage gives you 50 % increase in excitation current is called knee point voltage. To measure this first demagnetise the CT and apply voltage gradually from secondary keeping primary winding open circuited. while doing this above phenomeneo will be obsesrved.
How does a transformer change voltage and current?
A welding transformer uses the alternating current supplied to the welding shop at a high voltage to produce the low voltage welding power
Why transformer is called static device?
A transformer has two coils wound over a core. Depending on use, the two coils are named primary and secondary coils. The primary and secondary coils are linked magnetically (not electrically except in case of auto transformers) called mutual coupling. When the primary coil is excited with alternating voltage(A.C), varying magnetic flux is produced which links with the secondary coil and thus a voltage is induced in the secondary coil. Since there is no rotating or moving part utilized for the above process hence transformer is called a static device. The word static used here should not be confused for static charges. It only signifies "not moving"
Impedance of a 500kVA transformer?
When transformer secondary is short circuited & primary voltage is raised, current in the secondary winding increases from 0 to rated current (say, 667A at 433V), a small voltage appears at the secondary windings. This percentage of this voltage to the rated secondary voltage is expressed as %age impedance. IEC table 76-5 provides following details : Rated KVA %impedance Up to 630 4.0 631-1250 5.0 1251-3150 6.25 3151-6300 7.15 6301-12500 8.35 12501-25000 10.0 25001-200000 12.5 Also, it may vary from manufacturer to manufacturer. For example, for a transformer of 500kva, 4% impedance, rated current of 667A@433V , when secondary is short circuited & primary voltage is raised to drive a current of 667A in the secondary windings, 4% of 433V develops across it's secondary windings i.e. 17.32V. Now, the impedance is calculated as Z= V/I = 17.32/667 = 0.02596 ohms. This percentage impedance also decides the amount of fixed KVAr compensation required at the secondary of transformer. This is 4% x 500KVA = 20 KVAr Also, short circuit capability of transformer is calculated as 433/0.02596 = 16,679.50 Amps or approximately 17kA. Hope this information is sufficient. Also, one may again find a good answer to the above question as I've seen a transformer of 500kva with % impedance of 5.13 also. Regards, Asif Mansoori, DEE, Mumbra-Thane, India. asif_currents@hotmail.com
What is the standard output current of a transformer when connected to an ac?
There is no 'standard' output current from a transformer. The secondary (output) current depends on the load, and should not exceed the rated secondary current. To find the rated secondary current, you divide the transformer's rated volt amperes by the rated secondary voltage. The above cited answer need more descriptive ; a) V/Z = I, b) V/Z = I + Magnetizing current of the transformer taken from Primary side of the transformer.
How do you know the primary or secondary side of a transformer?
The primary side is usually labelled 'H', the secondary is often labelled 'L'.Primary wiring will often be smaller, since the current carrying capacity doesn't have to be as high on the primary side.The best thing to do would be to check with the manufacturer. They should have documentation stating what is primary and secondary.CommentThe above answer only applies to step-down transformers. The simple answer is that the primary winding is the winding connected to the supply, whereas the secondarywinding is the winding connected to the load. These terms have nothing to do with voltage levels.
What do you mean by no load of transformer?
Transformers voltage ratings are typically at full load. For instance, A 24 VAC, 10A transformer will have a terminal voltage of 24 when it is feeding 10 amps to a load. Since the transformer windings have some resistance, the transformer designer has to wind the transformer to put out more than 24 volts, since some of the voltage will be lost, dropped across the resistance of the secondary windings. But, according to Ohm's law, the voltage dropped across a resistance is proportional to the current (E=IR). If we take away the 10A load, there is no current, and therefore no winding voltage drop! The excess voltage the designer built in now appears at the terminals. This is the no-load voltage. In my example above, when we remove the 10A load, the output voltage of the transformer might rise to 26.4V. We would say the no-load voltage of that transformer is 26.4V The ratio of full-load voltage to no-load voltage is called the transformer's "regulation factor". It is calculated as: (no-load voltage - full-load voltage) / full-load voltage * 100. Ours is: ((26.4 - 24) / 24) * 100 = 10%.
What is knee point voltage of current transformer?
10 % increase in voltage gives you 50 % increase in excitation current is called knee point voltage. To measure this first demagnetise the CT and apply voltage gradually from secondary keeping primary winding open circuited. while doing this above phenomeneo will be obsesrved.
What is the capacitive voltage transformer in sub station?
A coupling capacitor voltage transformer (CCVT) is composed of two stacks of capacitors which step the primary voltage down to a lower voltage potential transformer. These are typically used on 100kV and above, and the potential transformer is often around 15kV on the primary side. There are two reasons to use CCVTs over PTs (potential transformers) - at the above voltage levels, they are cheaper, and they can be used for power line carrier signal injection. Under transient conditions, CCVTs typically won't perform as well as PTs, and also may have worse accuracy ratings, so are often not acceptable for metering purposes.
Can you use a step down transformer as a step up transformer by reversing the primary voltage as a secondary voltage?
If the transformer has two separate windings, then, YES a step-down can be used as a step-up, and vice-versa.It is more correct to say you are reversing the high and low sides.By definition Primary is the "IN" side and Secondary is the "OUT" side.The Primary could be the high voltage side if it is a step-down,or it could be the low voltage side, if it is a step-up.Design ConsiderationsCare must be taken when reversing the operation of a step-down transformer to insure that it does not exceed the ratings of the transformer. For example, let's say we have a 12 VA step-down transformer that takes 120Vac in and is rated to provide 12V at 1 amp at the secondary. If we were to reverse it and apply 12Vac to the new primary (the old secondary), we would have 120Vac at the new secondary, but to keep within the original ratings it could only be loaded to 0.1A @ 120Vac.As long as you treat the output rating of the step-down transformer as the input rating as a step-up transformer, and don't try to draw current beyond what would normally have been applied to the high voltage primary, you should be fine. Potentially one could push up the voltage on such a transformer beyond what its stated application specified, while making sure not to exceed the power rating of the transformer and not exceeding the breakdown voltage of the transformer's insulation, for example driving the above transformer at 24V to get 0.05A @ 240Vac. It is important to realize though that the rated input voltage for a step-down transformer will likely not be a safe input voltage if you use it as a step-up transformer - for example, applying 120V to the above transformer with the windings reversed would generate 1.2KV!One important point to remember when reversing a three-phase transformer to a step-up is what kind of windings it has. Most three-phase Transformers use a "delta" configuration on the primary side. This means that there are three "hot wires" and a ground, but not a neutral. (The white wire in a circuit). On the secondary side, transformers are usually wired up in a "Wye" (sometimes called a "star" configuration. Doing this allows the transformer to create a Neutral connection. If a step-down transformer is reversed to make it a step-up, the high (output) side will not have a Neutral connection. If one is not needed, say for a three-phase welding machine, this would not be a probem. However, if a Neutral IS needed ,say for lighting, reversing this transformer would not work. In this case, a listed step-up transformer will be needed. One final thing, if a step-down transformer is used as a step-up, a Neutral wire is not required to be connected to the input side.
Why current transformer secondary side short circuit?
A current transformer (or CT) is constructed in a specific way so as to step down the current in a high power circuit for measuring or protective relaying purposes. Typically, it will have a toroidal-shaped iron core with the secondary windings wrapped around it. the primary "winding" is usually the conductor of the main power system passing directly through the hole in the center of the CT. As a result of this construction, if the secondary windings are left open, a very large flux can develop, resulting in damage to the CT and possibly even the other equipment it is attached to. As such, if the CT is not going to be used, its secondary windings need to be shorted.
How does a transformer change voltage and current?
A welding transformer uses the alternating current supplied to the welding shop at a high voltage to produce the low voltage welding power
What is the difference between a step up transformer and a step down transformer?
the main function of transformer is to change the magnitude of Voltage. difference between step up and step down is step up will change the input voltage into a larger magnitude of output while step down is vice versa
Formula for relation between primary winding and secondary winding?
The turns ratio of Primary / Secondary tells you have the voltage and current will be changed. The secondary current will be (primary turns/secondary turns) times the primary current, and the secondary voltage will be (secondary turns / primary turns) times the primary voltage.CommentThe above answer is a little misleading, because the secondary current is determined by the load, and not by the transformer's ratio. It would, therefore, be more accurate to say that the primary current would be equal to the secondary current times the (primary turns/secondary turns) -i.e. not the other way around!
What is transformative use?
the Transformer depends up on the Voltage transformer input Voltage 230 V . out put volt depend upon the secondary winding of the coil with swg coil ( copper Thickness) Ex 230 V input = step-up Transformer = above 230 v ( like 440 v, 1000v but same current) 230 V input = step-down Transformer = below 230 v ( like 3 ,6,9,12,24,110v, but same current)
Why transformer is called static device?
A transformer has two coils wound over a core. Depending on use, the two coils are named primary and secondary coils. The primary and secondary coils are linked magnetically (not electrically except in case of auto transformers) called mutual coupling. When the primary coil is excited with alternating voltage(A.C), varying magnetic flux is produced which links with the secondary coil and thus a voltage is induced in the secondary coil. Since there is no rotating or moving part utilized for the above process hence transformer is called a static device. The word static used here should not be confused for static charges. It only signifies "not moving"
