What is the Difference Between a Current Transformer and a Current Transducer?

A current transformer

What Do We Understand by a Current Transformer?

A current transformer is an electrical device or instrument that can transform a higher current value to a lower one in a fixed proportion. It performs this action by converting the magnitude of a high voltage current into a low voltage current. As a result of this conversion, the heavy current passing or flowing through a transmission line can get monitored and controlled safely with the help of an ammeter. 

A current transformer can do the opposite as well. It can transform a lower value of the current into a proportionately higher one. However, proportionality must exist between the primary and secondary coils of the instrument. 

In a current transformer, the primary current does not depend on the load current from the secondary coil. Instead, it gets controlled and influenced by an external load. 

Electrical Switchgear buss with current transformers

In most cases, a current transformer gets used with any instrument, control apparatus, meters, or appliance that works on alternating current. In such cases, the current that has to get measured remains at such a high or low magnitude that the coils of the devices can use them conveniently and efficiently. 

A current transformer serves as the current-sensing components or units of a power system. They get used actively in generating stations, commercial and industrial electric power supply and distribution lines, and electrical substations. 

A current transformer can be of four primary types. The kinds comprise the following:

Wound Current Transformer

A wound current transformer has its primary coil or winding connected physically in series. This linkage is with the conducting material or substance that carries and holds the computed current flowing or passing through the circuit. The magnitude of the current at the secondary coil depends on the turns ratio of the instrument. 

Toroidal Current Transformer

A toroidal current transformer does not have any primary winding. A line carrying the current that flows in the circuit remains threaded and wound through a hole or window in the instrument. Some variations of this device may also come with a split core. It allows the system to get installed, closed, and closed without disconnecting the attached circuit. 

Bar-Type Current Transformer

A bar-type current transformer utilizes the chief circuit’s bus-bar or a cable to form the primary winding. It is generally equivalent to one turn. It remains entirely insulated from the system’s high voltage. Additionally, it comes bolted to the current-conducting device. 

Summation Current Transformer

A summation current transformer collects several outputs and supplies them to a single transformer. The latter component converts the amalgamated value into a single one. It helps significantly in reducing and preventing the hazards and costs of installing multiple pieces of equipment. It also curbs the metering complexity, wiring expense, and so on. 

What Do We Understand by a Current Transducer?

A transducer is an electrical device or instrument that can alter and transform any one state of energy into another. In typical cases and instances, it can transform and change one form of a signal into some other kind. 

Depending on the type of conversion that a transducer performs, it may be of different and distinct varieties. A current transformer is one such example. Under this category, the transformation is between two components, the first of which is current. 

Let us put it in simple words. A current transducer can convert a current of any magnitude or value into a conventional electrical and analog signal. This standard output has to be proportional to the industrial norms and specifications. 

Current transformer substation

In addition to that, the electrical device can measure and compute the variable nature and state of electricity. It can translate or convert it into a specific type of data that a process control system can interpret and comprehend. In general cases, the current range that a current transducer can assess falls under a fixed and unchangeable scope. For that reason, it is exceedingly essential to consider the kind of job or task the instrument will perform and the working environment before installing it. 

A current transducer can get categorized into two types that entail:

Absolute Average Measuring

These current transducers convert the AC (alternating current) input into a DC (direct current) output. The ultimate magnitude gets calibrated. It is to depict the RMS (Root Mean Square) value for the input’s sine wave. Such current transducers find application when the current remains undistorted. 

True RMS Measuring

These current transducers compute the RMS value of the input current. They use it to generate a DC output. The latter remains proportional to the former’s effective value. Such current transducers get used when the current becomes distorted. 

Current transformers

What are the Various Points of Difference between a Current Transformer and a Current Transducer?

A current transformer and a current transducer may have similar names. However, the two of them have significant differences. A few of such distinctions and disparities include:

Function and Use

The primary difference between a current transformer and a current transducer lies in their function and use. The former works and operates to increase or decrease the value or magnitude of the current that comes in as input. Therefore, the output and its counterpart do not remain the same. 

On the other hand, a current transformer merely affects the state of energy. It converts and transforms current into an analog and electrical form of energy that a machine like a process control system can interpret and understand. 

Change in the Magnitude or Value of the Current That it Works on

A current transformer does not affect the magnitude of the current that it works on in any manner or way. It merely alters and changes its state or form into the required and preferred one. 

A current transducer affects and influences the magnitude or value of the current that it uses. It either increases or decreases it as necessary for a particular application. A higher value of the current coming in from the primary coil gets lowered at the secondary coil. The vice versa also stands true.

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