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yes........ we can short circuit the other side of the winding wen the primary is excited.... but we shouldn't apply rated voltage to the primary.. this method is used in the short circuit test of the transformer to find the parameters of the transformer.....
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If a dc voltage of 12v is added to the secondary of step down transformer and rating of transformer is 220 input and 12v output what will be the result from primary of transformer?
A DC voltage added to one side of a transformer has no effect on the other side.
Why LV side is shorted in short circuit test?
Transformer short circuit tests are used to determine the impedances (positive and zero sequence) of the transformer. A simple explanation: to do this one winding is shorted, and voltage is applied to another winding to circulate the normal full load current of the transformer. The impedance of the transformer is the applied voltage divided by the induced current. If one winding was not shorted, the voltage divided by induced current would not give the impedance of the transformer - the induced current would be much lower, giving a much higher impedance measurement that would be essentially meaningless.
Does a 3 phase motor starter with a 120 volt coil need a neutral to the coil?
Usually for this type of installation there is a control transformer installed in the starter enclosure. The primary of the transformer is the motors line voltage and the secondary is the control voltage which is usually 120 volts. In Canada the control transformer needs fusing on the secondary side of the transformer. In the US the transformer needs fusing on the primary and secondary sides of the transformer. The secondary side of the transformer's terminals are labeled X1 and X2. The X2 lead is grounded to the starter's enclosure. From this point out the wire is then termed the circuit's neutral wire. This wire then connects to one side of the magnetic starters draw in coil. Yes, 120 volt coil would require a neutral, this could be derived from the control transformer if it has one or from an external source.
What is percentage impedance?
In electrical engineering, the percentage impedance of a transformer is the voltage drop on a full load, which is expressed as a percentage of the specified rated voltage. It's measured by conducting a short circuit test.
If voltage is zero or very low on one phase and the same as line to line voltage on the other two. Is there a short to ground on the low voltage phase?
From your question it's hard to tell what might be the source of your problem. Is this a primary source to a machine or multiple circuits or from a transformer to just one device like a motor. If it is a short to ground then it should be tripping fuses or breakers if not then you have a unsafe situation in a ungrounded system. If the power is from a transformer then it may have an open winding or blown fuse on either the primary or secondary side.
What should be the short circuit setting of the feeder breaker of a transformer so that it does not trip on short circuit fault in secondary side?
You need to model this - the line impedance and transformer impedance, and the voltage will determine this. There is no "one size fits all".
If a dc voltage of 12v is added to the secondary of step down transformer and rating of transformer is 220 input and 12v output what will be the result from primary of transformer?
A DC voltage added to one side of a transformer has no effect on the other side.
Why LV side is shorted in short circuit test?
Transformer short circuit tests are used to determine the impedances (positive and zero sequence) of the transformer. A simple explanation: to do this one winding is shorted, and voltage is applied to another winding to circulate the normal full load current of the transformer. The impedance of the transformer is the applied voltage divided by the induced current. If one winding was not shorted, the voltage divided by induced current would not give the impedance of the transformer - the induced current would be much lower, giving a much higher impedance measurement that would be essentially meaningless.
What is the difference between an isolation transformer and distribution transformer?
in isolation transformer earthing is not provide on secondary side but in ordinary transformer neutral of secondary side is earthedAnswerAn isolation transformer is a 1:1 ratio transformer; its function is to electrically isolate the secondary side from the primary side without changing the voltage. An example of an isolation transformer is the one used in a shaver socket.A distribution transformer is a step-down transformer, used within the electricity network's distribution system. An example of distribution transformer is a pole-mounted transformer, supplying low voltage to residences.(Of course, all mutual transformers provide electrical isolation between primary and secondary.)
What will happen you f the rated power of transformer is changed?
You cannot 'change' the 'rated power' of a transformer except by changing the transformer for another one. You can, though, operate the transformer below its rated power or, for short periods of time, operate the transformer aboveits rated power.
What is a tap changing transformer?
A transformer that has part of one winding partitioned in such a way that it can be removed or added to the winding. For example, you may have a transformer with 100 turns on the low side and 1000 turns on the high side. If it were a tap changing transformer on the high side winding, you may be able to add or subtract 100 turns, so the turns ratio can be anywhere from 9/1 to 10/1. <<>> This type of transformer is in common use in home distribution systems. On the side of the transformer there is a handle with the markings of 14,400/7200. By having this ability to work on two different primary voltages the utility only has to stock one transformer. The same transformer can be connected to the grid across phases at 14,400 or phase leg to ground at 7200 volts. The transformer ratios are so wound that the output voltage remains at 120/240.
What is transformer tap changing?
A transformer that has part of one winding partitioned in such a way that it can be removed or added to the winding. For example, you may have a transformer with 100 turns on the low side and 1000 turns on the high side. If it were a tap changing transformer on the high side winding, you may be able to add or subtract 100 turns, so the turns ratio can be anywhere from 9/1 to 10/1. <<>> This type of transformer is in common use in home distribution systems. On the side of the transformer there is a handle with the markings of 14,400/7200. By having this ability to work on two different primary voltages the utility only has to stock one transformer. The same transformer can be connected to the grid across phases at 14,400 or phase leg to ground at 7200 volts. The transformer ratios are so wound that the output voltage remains at 120/240.
What does a step-down transformer do to the electrical current?
A step-down transformer lowers the voltage of an AC current. The higher AC current is put through one side and the other side the lower AC current is delivered.
Can fused feeders for the line side of a transformer pass through the same gutter with the load side of the same transformer?
As long as the voltage insulation factor of the conductors are the same and they are of the same circuit fed by the primary side of the transformer's disconnect switch then yes the two feeders can be run together. It is not usually done though because the transformers feeders usually start at an MCC or splitter of one voltage and the load side of the transformer usually goes to a distribution point of some sort at a different voltage.
Does a 3 phase motor starter with a 120 volt coil need a neutral to the coil?
Usually for this type of installation there is a control transformer installed in the starter enclosure. The primary of the transformer is the motors line voltage and the secondary is the control voltage which is usually 120 volts. In Canada the control transformer needs fusing on the secondary side of the transformer. In the US the transformer needs fusing on the primary and secondary sides of the transformer. The secondary side of the transformer's terminals are labeled X1 and X2. The X2 lead is grounded to the starter's enclosure. From this point out the wire is then termed the circuit's neutral wire. This wire then connects to one side of the magnetic starters draw in coil. Yes, 120 volt coil would require a neutral, this could be derived from the control transformer if it has one or from an external source.
How differential protection work in a transformer?
Power flowing into a transformer must match the power flowing out (minus losses which are minimal). If this is not the case, there's something wrong. Differential protection monitors current only; Current flowing into one side of the transformer will be equal to current flowing out the other side scaled by the turns ratio of the transformer. Since the turns ratio is equivalent to the voltage ratio, this is easily set.
What is percentage impedance?
In electrical engineering, the percentage impedance of a transformer is the voltage drop on a full load, which is expressed as a percentage of the specified rated voltage. It's measured by conducting a short circuit test.
