Current transformers

Designed to safeguard against electrical surges, Metrosil Current Transformer Protection Units (CTPU) and CTPU Enclosures offer engineers and power generation operators reliable protection from a single supplier.

Providing an effective solution for safeguarding current transformers against secondary side open circuits.

Single Pole Metrosil Current Transformer Protection Unit

current Transformer protection units

CTPU Design Specification

A Metrosil CTPU can be constructed in both single and three pole varieties. All CTPUs are factory audited to ISO9001-2015. Please download our Metrosil CTPU data sheet before following the ordering instructions below:

  • Using the data sheet, identify the relevant table for the application
  • Select the Metrosil CTPU type
  • Check the leakage current through the Metrosil CTPU with the burden connected
  • Check the peak voltage which the CTPU limits the open circuited system to
  • Confirm if a second thermostatic switch is required


Metrosil pre-assembled CTPU Enclosures safeguard against the damaging effects of secondary side open circuits. Backed by extensive technical support and design assistance, the robust units offer a safe and reliable solution for current transformer applications.

  • Type tested and independently certified to IEC 61439 Parts 1 and 2 IP66-compliant
  • Offer adaptable configurations based on three standard cabinet sizes for specific application needs
  • Provide flexible fitting options to meet diverse site requirements
  • Include an integral basic protection barrier to safeguard against electrical surges

current Transformer protection units

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