What are current transformers?

A Current Transformer (CT) is used to evaluate the current of another circuit. CTs are used worldwide to screen high-voltage lines across open power grids. A CT is planned to convey a pivoting current in its discretionary winding that is comparing to the current that it is assessing in its fundamental. In doing all things considered, the stream transformer diminishes a high voltage stream to a lower regard and accordingly gives a secured technique for noticing electrical stream spilling in an AC transmission line.


Operational threats can occur if the discretionary circuit of a CT is left open while the fundamental is enabled. Open circuit conditions can happen by chance through routine help of the weight or mischief to the leads of the discretionary circuit. High voltage vagrants may be created in these conditions and mischief the CT winding insurance; possibly conveying it inoperable. Likewise, these wanderers can cause high whirlpool streams in the CT community. These may be negative to the polarizing credits of the CT and result in botches in the assessment exactness.

IEEE C57.13 prompts that voltage limiting devices should be outfitted with discretionary windings to get against risky voltages. Metrosil Current Transformer Protection Units (CTPUs) offer such security and, not in any manner like other voltage confining contraptions, don’t ought to be displaced following an irregular condition. They can remain in-situ without the necessity for customer intervention.


Under customary working or blemish conditions, with the weight related, the varistor is presented to an applied voltage. It goes probably as a standoffish weight and draws insignificant current, thusly hindering blunders in the assessment of the CT. During an open circuit condition, the varistor is presented to an applied current and goes probably as a working weight. It as needs be confines the voltage across the CT terminals and thwarting any mischief. The thermostatic switch manages the warm cycling inside the Metrosil CTPU when the CT is in an open circuit condition. A second thermostatic switch can be mounted on the glow sink plate for removed checking. Metrosil varistors can deal with the degree of a back EMF by scattering set aside energy insider savvy to a reasonable weight.

A Metrosil CTPU can be created in both single and three post collections for convenience of foundation. All CTPUs are creation line assessed to ISO9001-2015. Metrosil CTPUs shield CTs from hurt under open circuit conditions. They don’t shield hand-off or CT systems from overvoltages made as a result of high helper issue streams. For security of high impedance move structures against overvoltages during inadequacy conditions, if it’s not all that much difficulty, insinuate our Metrosil Relay Data Sheet. For assist with using Metrosil CTPUs identified with Metrosil Relays for High Impedance Relay Systems, if it’s not all that much difficulty, contact the Metrosil gathering.


Metrosil’s extent of pre-assembled CTPU Enclosures give advanced ensuring against the hurting effects of assistant side open circuits. Type attempted and uninhibitedly guaranteed to IEC 61439 Parts 1 and 2, the units are available in flexible plans and versatile fitting decisions.


Metrosil Silicon Carbide varistors were a consequence of the great voltage part of Metropolitan-Vickers in 1936 and mass made in 1937. As a critical awe-inspiring phenomenon in the 20th century, Metrovicks was prominent for its mechanical electrical stuff, which included generators, steam turbines, switchgear, transformers, equipment and rail course balance equipment. In this manner, Metrosil resistors were shown into critical lead broadens that prepared for the beneficial scattering of force. Straight up until the here and now our resistors stay set up inside set up power associations, which has instilled trust in major OEMs and utilities the equivalent. As present day power establishments make, we continue to improve and be resolved into substations on an overall reason.