Electrical instruments aren’t effectively connected to high voltage meters or control apparatus for safety reasons. Instrument transformers, such as voltage and current transformers, are used to connect electrical instruments with measuring instruments.

These transformers decrease the current and voltage from high to low levels that can be measured with standard instruments. Because both the current and prospective transformers have an electromagnet in their secondary windings. There are numerous differences between voltage and current transformers.

Table of Contents

Scroll down to get your hands on in-depth information about the two transformers and what makes them differ from each other, right from their purpose to their input values and more.

What is a Current Transformer Used For?

A current transformer converts higher-valued current to lower-valued current with reverence to earth potential. It has been used with AC instruments to measure high current values. The line current is high, & measuring it directly is difficult. Thus, a current transformer is often used to convert a high value of the current into a partial value that the instrument can easily measure.

What is a Voltage Transformer Used For?

Voltage transformers are machines that are used to step down and reduce the voltage of a system to a safe level. It works by allowing energy meters to monitor the maintenance of power connections that require a greater voltage function properly. It is used in electrical metering,

Safeguarding electrical instruments and providing shields for the feeder. Voltage signals are critical for synchronization, event logging, and event recording. A measurement process determines O/F, O/V, U/F, U/V, as well as some excessively fluxing protection.

What are The Types of Voltage Transformers?

Below are some of the chief types of voltage transforms, alongwith their purposes.


As it has a wire-wound core, this transformer is similar to an oil-filled coiled wire transformer. In this type of transformer, the primary voltage is completely converted to secondary voltage through the use of electromagnetics. Electromagnetic voltage transformers can be used for a variety of purposes, including:

  • Working in the electrical metering field.
  • Keeping electrical instruments safe.
  • Giving the feeder some protection.
  • Making generators resistant to damage.
  • Establishing industrial electrification


This converter can be considered a hybrid device because it combines a capacitive voltage divider as well as a magnetic transformer. In the industry, these transformers are known as intermediary inverters with low ratios. This category of the transformer, which is made up of a stack of elevated capacitors, can be used for voltage metering as well as a protection system. As a consequence, the capacitors could lower the voltage levels, which a transistor then steps down to an auxiliary voltage level.


Optical voltage transformers are a relatively new type of energy transformer that can be used instead of traditional electric-magnetic converters for safety & metering applications. Its advantages have been extensively discussed in science-technical literature, and its company operations are widely recognized and developed in the market. Because of the high costs and the newness of the technology, many electric plant workers try to avoid them. It is not managed by local specialists, instead calls for manufacturers to work on large contracts to ensure a smooth functioning.

As it has already been proven that optical technology has its set of advantages and disadvantages, the research of alternative electro-optic solutions became the main objective of high-tech lab conditions, as well as the prime objective of current work.

Difference Between Voltage Transformer and Current Transformer

One significant difference is that a current transformer converts high current values to low voltage values, while the voltage transformer converts high voltage values to low voltage values. Here are some other major factors that make them differ from each other.


One of the most significant differences between the two transformers is their functions. A current transformer diminishes a current flow to a safer and much more controllable level that can be measured. Large primary currents are composed of short 1A/5A currents which can be evaluated with an ammeter.

A voltage transformer on the other hand measures as well as reduces high voltage values. It reduces the high voltage to a basic secondary frequency of 100 volts or less.


The core category of the instrument can be used for high and low voltages both in constant voltage transformers as well as outdoor low voltage transformers. Its core is made of high-quality materials and can magnetize small currents at low density. Typically, silicon steel laminations are used to create the core of a current transformer, while a voltage transformer is crafted using industrial-grade steel that world at low flux densities in order to allow the unit to work effectively.

Winding, both primary and secondary

Speaking of a current transformer, the primary winding features fewer turns and carries the current that needs to be measured. In voltage transformers, the primary winding sports many turns while carrying the voltage that needs to be measured.

The secondary winding on a current transformer comes with more turns on the secondary side, while being hooked to the unit’s current winding. In a voltage transformer, the secondary winding features fewer turns on its secondary side, while being hooked to the meter.


Voltage transformers (whether low voltage or high voltage transformers) concentrate on the source of power, measurement, and operation of a protective relay. The current transformer measures power and current. It also checks with the electric grid operator to ensure that the relay is operational and secure.


A 5 Ampere ammeter could be used with the current transformer to assess high currents up to 200 Amperes. A voltage transformer, on the other hand, allows you to use a 120V voltmeter to evaluate high voltages like 11KV.

Input Value

The input value of a current transformer is constant current, while the input value of a voltage transformer is constant voltage.


In terms of importance in electricity, voltage transformers and current transformers are undeniably equal. While some can be low voltage transformers, the others are high voltage transformers. Eventually, current transformer & voltage transformer testing focuses on ensuring that device transformers are functioning properly. It also ensures that voltage and current stay within their limits. Transformers protect your electrical devices or home appliances from unexpected electrical issues.

Nelson James
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