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Transformer Types and Instrument Transformers

Posted by mb

1. Introduction to DC Current Transformers

We design DC current transformers as mutual inductance devices for DC current conversion. Specifically, they leverage the nonlinearity and asymmetry of the core coil, and this happens when both DC and AC currents magnetize the core.

Moreover, through a rectifier circuit, these transformers convert large DC currents in the primary coil; the output is proportional small DC currents, and importantly, the current ratio maintains an inverse relationship with the number of coil turns.

2. Core Applications and Advantages

DC current transformers primarily measure large DC currents, and additionally, they act as key components in rectifier systems.

Specifically, their roles in rectifier systems include current feedback, control and protection. When compared with shunts, they have distinct advantages.

These advantages, in particular, are lower power loss and effective electrical isolation.

3. Working Principle of DC Current Transformers

3.1 Basic Operating Principle

DC current transformers are dedicated to DC current conversion, and they operate based on core coil characteristics.

These characteristics are nonlinearity and asymmetry, which occur under combined DC and AC magnetization.

Specifically, they step down large primary DC currents via a rectifier circuit; as a result, the output is smaller secondary DC currents, and the current ratio correlates inversely with the number of primary and secondary turns.

Furthermore, their applications go beyond large DC current measurement, as they also provide current feedback, control and protection in rectifier systems.

Again, compared with shunts (refer to ammeters), they feature lower power consumption, and they also have reliable electrical isolation.

3.2 Ideal Operating Conditions and Current Ratio Relationship

Under ideal operating conditions, the secondary winding bears a voltage difference, and this winding is wound around the unsaturated core.

Specifically, the voltage difference exists between the supply voltage U and the voltage across load resistor Rx.

Meanwhile, the relationship N₁I₁ = N₂I₂ holds true, and it can also be expressed as I₁/I₂ = N₂/N₁ (I₂ denotes the secondary current).

In other words, this means the primary-secondary current ratio is inversely proportional to the turn ratio.

After rectification, we can measure the secondary current I₂ directly with a DC ammeter; alternatively, we can calculate it by measuring the voltage drop across Rx.

Transformer Types and Instrument Transformers

1. Introduction to DC Current Transformers

2. Core Applications and Advantages

3. Working Principle of DC Current Transformers

3.1 Basic Operating Principle

3.2 Ideal Operating Conditions and Current Ratio Relationship

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Transformer Types and Instrument Transformers

1. Introduction to DC Current Transformers

2. Core Applications and Advantages

3. Working Principle of DC Current Transformers

3.1 Basic Operating Principle

3.2 Ideal Operating Conditions and Current Ratio Relationship

Recent Posts

Indoor vs Outdoor Current Transformer Differences

Split Core vs Solid Core Current Transformer

Combined Instrument Transformer Working Principle

If you are interested in our products, feel free to contact us anytime!

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