Current Transformers

Sirio is a leading manufacturer of electromagnetic components for applications in industrial electronics. Their range of power transformers has been used in high frequency insulated power converters over the last ten years. Manufactured by a special dedicated automatic machine, Sirio's power transformers are widely used in demanding, high power applications with very high reliability expectations. 

Today, Sirio is one of the world's leading manufacturers of power transformers, specilaising in the development and production of current transformers, with more than a quarter of a million power transformers in the field.

Download Sirio's High Frequency Power Transformers and Inductors Brochure

Main Frequency Current Transformers

Main frequency current transformers are used to measure alternate currents at 50-60 Hz, up to 600 Arms.

They are based on toroidal Silicon Iron core; they typically have a high number of secondary turns, so that the secondary current is relatively low. By connecting a burden resistance to the secondary side, you can read a proportional voltage signal, isolated from the mains. As the secondary current is low, the low power burden resistance can be connected to the PCB.

Current transformers are used to measure and detect alternate currents by keeping the galvanic isolation between the primary cable (the network) and the control stage. They typically have a high number of secondary turns, so that the secondary current is relatively low. By connecting a burden resistance to the secondary side, a proportional voltage signal, isolated from the mains can be read. As the secondary current is low, the low power burden resistance can be connected to the PCB.

Current Transformers for Measurement Applications

Current transformers for measurement purposes are used to measure alternate currents at 50-60 Hz, up to 50 Arms. They are typically used in energy metering applications, where high accuracy and small dimensions are required at the same time.

Current transformers for measurement applications are available in two different versions; with passing-through hole and with the primary turn inside, this was developed to get an easier assembly process on the PCB.

Current Transformers for High Frequency Applications

Current transformers for high frequency applications are used to detect high frequency currents, in order to protect an electronic switch against overcurrents in switching converters. They are typically connected at the primary side of medium-high power high frequency transformers, but they are also suitable for currents measurement, in applications which do not require high accuracy, but prompt response of the measurement equipment instead. 

They are developed to detect alternate currents in the frequency range of some kHz. By connecting a burden resistance to the secondary side, you can read a proportional voltage signal, isolated from the mains. Depending on the application, other types of signal processing are available to use either by using digital or analogue techniques.

EE Core Based Drive Transformers

Pulse transformers are used in high frequency power converters, when an electrical pulse has to be transferred from the control stage to the power stage, by keeping the galvanic isolation between the circuits, according to the required safety standards. The electrical signal is applied to the primary winding and transferred to the secondary side, to fire electronic switches. The 109, 117 and 118 families are based on different sizes of EE cores.

The part numbers listed below are some examples, Sirio can also develop special drive transformers with any turns ratio, dedicated and bespoke to your application.

Low Coupling Capacity Gate Drive Transformers   

Sirio's low coupling capacity gate drive transformers is a crucial component in today's industry, the low coupling capacity between the windings is particularly important to avoid any unwnated firings of electronic switches. 

They are predominantly used in the multiple shot firing technique. Standard versions are designed with one or two secondary windings and the automatic winding process enhances their quality and price ratio.

Ring Core Based Gate Drive Transformers  

The electrical signal is applied to the primary winding and transferred to the secondary side, to fire electronic switches. The 111, 112, 113 and 114 families are based on different sizes of ring cores. The characteristics of these components are very different because several magnetic core materials and sizes can be used and different winding distributions can be chosen. 

Laminated materials are a preferred option for most engineers because they have much higher values of saturation flux density compared to ferrites which allows reduced dimensions, especially for medium-low switchingfrequency values (some tens kHz), and a much stable behavious with temperature, making them the ideal solution for critical environment conditions. Ferrites are the most cost effective option for engineers and toroidal components, similarly to the laminated materials, offer impressive technical features.

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