Transformer when output circuit is open

In summary, when the output circuit is open and there is no current flowing through the output coil, only the magnetizing inductance and leakage inductance of the primary are seen. As impedance is added to the secondary, it is reflected back to the primary in parallel with the magnetizing inductance, causing a larger current to flow through the input and potentially burning the wire. This happens because there is no back emf in the primary. The magnitude of the transformed secondary impedance in parallel with the primary magnetizing inductance is dependent on the number of turns on the primary and secondary coils.
  • #1
ahmadriaz
4
0
can u explain what hapens output circuit is open and no current is flowing through output coil? isn't it that a large current flows through the input?and the wire burns...i know it doesn't hapen...but why?when there is no back emf in primary?
 
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  • #2
ahmadriaz said:
can u explain what hapens output circuit is open and no current is flowing through output coil? isn't it that a large current flows through the input?and the wire burns...i know it doesn't hapen...but why?when there is no back emf in primary?

When the secondary is open, all you see is the magnetizing inductance (and the leakage inductance) of the primary. As you add impedance to the secondary so that some secondary current starts to flow, that secondary impedance is reflected back to the primary, where it appears in parallel with the magnetizing inductance of the primary.

Quiz Question -- What is the magnitude of the transformed secondary impedance, as seen in parallel with the primary magnetizing inductance, in terms of the number of turns on the primary and secondary coils?
 
  • #3


When the output circuit of a transformer is open, it means that there is no closed loop for the current to flow through in the secondary coil. This results in no current flowing through the output coil. In this situation, the transformer is not able to step down the voltage and provide power to the load.

If there is no current flowing through the output coil, then there is also no back emf (electromotive force) in the primary coil. Back emf is the opposing voltage that is generated in the primary coil due to the changing magnetic field caused by the alternating current. This back emf helps to limit the current flowing through the primary coil.

Without the back emf, there is no limitation on the current flowing through the primary coil. This can lead to a large current flowing through the input, which can cause the wire to overheat and potentially burn. However, most transformers have protective measures in place to prevent this from happening, such as fuses or circuit breakers.

In summary, when the output circuit of a transformer is open and there is no current flowing through the output coil, it can result in a large current flowing through the input. This can potentially lead to overheating and damage, but proper safety measures are in place to prevent this from happening.
 

1. What is an open output circuit in a transformer?

An open output circuit in a transformer refers to a situation where the transformer's secondary winding is not connected to any load. This means that there is no complete path for the current to flow through, resulting in no output voltage being produced.

2. What causes an open output circuit in a transformer?

An open output circuit in a transformer can be caused by a variety of factors, such as a faulty secondary winding, loose connections, or a blown fuse. It can also occur if the transformer is not properly connected to a load.

3. What are the consequences of an open output circuit in a transformer?

The consequences of an open output circuit in a transformer can vary depending on the type and size of the transformer. In general, the transformer will not be able to deliver any power to the load, and there may be a risk of overheating or damage to the transformer if it continues to operate with no load.

4. How can an open output circuit in a transformer be detected?

An open output circuit in a transformer can be detected by measuring the output voltage with a voltmeter. If there is no output voltage, it is likely that the circuit is open. Other signs of an open output circuit may include abnormal noises or a burning smell coming from the transformer.

5. How can an open output circuit in a transformer be fixed?

The solution for fixing an open output circuit in a transformer will depend on the cause of the issue. In some cases, it may be as simple as reconnecting a loose wire or replacing a blown fuse. However, if the secondary winding is faulty, it may require professional repair or replacement of the transformer.

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