Innovations in recent years have made current transformers more efficient with compact designs, making them easy to transport, store and install. The right choice of current transformer is decisive for the metering or protection system to work properly. Before choosing the right product, you should be aware of the advantages of using current transformers.
Advantages of current transformer
The current transformer has many benefits for the electrical circuit.
Measures high currents
The main purpose of the current transformer is to produce, from the primary current, a proportional secondary current that can be measured easily or used to control various circuits. The larger current values can be easily measured.
Current transformers can be used in a synthetic circuit to measure the fault current, facilitating the safe measurement of large currents, often in the presence of high voltages. The primary winding is connected in series with the source current to be measured, while the secondary winding is normally connected to a meter, relay, or a burden resistor to develop a low-level voltage that is amplified for control purposes.
High effective cores
Commonly, cores with high effective permeability are used in current transformers to minimize magnetizing current and reduce errors.
High electrical isolation
Its capability to isolate the high voltage and current to low values ensures safe operations and safe handling of the equipment. Current transformers offer electrical isolation among measuring instruments & high voltage power circuits. So that electrical insulation requirements can be reduced in protective circuits & measuring instruments.
Current transformers are widely used as measurement or protective transformers. Another advantage of the current transformer is its simple construction and ease of installation.
Easy supply and control functions
A CT is powered by the current it measures. It does not require additional power. Besides, the output signal of a CT can directly trigger the electromechanical relays. It does not require additional amplification.
Numerous instruments can be fed with a single transformer. Besides, the measurement results are not affected by the temperature of windings or magnetic cores, if within acceptable limits.
The placement of the current transformer sets limits for the shape and size. The current transformer is placed inside the induction motor’s terminal box, around the phase conductor. This limits the maximum size of the transformer core. Clamp-on cores can be used to ease the installation so that the transformer can be installed without disconnecting the phase conductor from the motor end.
Easy maintenance and installation
Damaged parts of a CT can be easily replaced. Current transformers have robust mechanical strength and a compact design. They are easy to transport, store and install. Besides, they are maintenance-free throughout their lifespan.
With the standardization of C.T. secondary winding ratings, it is possible to standardize instruments around these ratings and, therefore, there is a great reduction in the costs of current transformers and instruments.
Safe AC measurement
Current transformers do not allow the measurement of DC signals, so they cannot be suitable for dielectric discharge detection; however, they can be used in the measurements of inductive currents and voltage waveforms with secondary load impedance. External magnetic fields barely affect the measurement results.
Current transformers have various types such as molded case current transformer, summation current transformer, cable split-core current transformer, three-phase current transformer, DIN rail current transformer, compact current transformer, flexible current transformer, split-core residual current transformer, differential current transformer. All these types have different functions.
CTs can be used in wide applications such as branch circuit power monitoring, substation error detection, the current measurement for motor protection, industrial electricity metering, and smart electricity metering.