CTDim – Current and voltage transformer selection, dimensioning and simulation

Electrical power systems are continuously evolving – influencing changes to the secondary control and protection applications. Due to these impacts, engineers require a tool that accurately enhances the process of selection and optimization of instrument transformers to fit the modern power system protection and control equipment. With CTDim, engineers can optimize the selection and dimensioning of instrument transformers, while meeting technical requirements of modern digital relays and decreasing costs.

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CTDim software

Select and optimize your instrument transformers to best fit the protection and metering applications

CTDim is a software tool for current transformer (CT) and voltage / potential transformer (VT / PT) selection and dimensioning. By optimizing the selection of CT or VT data with respect to technical requirements of power system protection and/or metering, the engineering and production costs can be substantially reduced while maintaining technical excellence. CTDim provides clear benefits to your customers and all involved parties.

CTDim standard features

  • Straightforward check whether selected CTs and VTs data fulfill requirements of connected devices. Both protective  as well as metering CT cores are included. Dimensioning of VT protective and metering windings is covered. 
  • Powerful documentation: Short and long reports are prepared automatically (easily editable rich text format RTF)
  • Supports overcurrent protection, distance protection, line differential protection, transformer protection, generator protection, motor protection, busbar protection, as well as a wide range of high impedance protection schemes
  • Supports both non-gapped and gapped (non-remanence) CT cores:
    - IEC protective CT classes: 5P, 10P, 5PR, 10PR, PX (former BS Class X), TPX, TPY and TPZ 
    - ANSI protective C, T and X Class
    - IEC metering classes: 0.1, 0.2, 0.5, 1, 3, 0.2S and 0.5S
  • Transient simulation of CT behavior (e.g. time-to-saturation) for all the above mentioned protective CT classes and protection devices. COMTRADE export function allows further analysis and even hardware testing
  • Rct (internal CT resistance) estimation
  • Long list of supported meters and relays: Siemens SIPROTEC numerical relays  (SIPROTEC 3, SIPROTEC 4, SIPROTEC 5), as well as large number of non-Siemens devices

Save engineering and production costs by properly selecting and optimizing your instrument transformer data

Benefits of using CTDim

  • CT and VT burden check avoids extensive under-burdening of instrument transformers and helps when specifying instrument transformers
  • Savings in engineering and production costs by optimizing the CT and VT data
  • Consideration of latest international instrument transformer standards
  • Powerful reporting tool clearly documents the selection steps using flexible rich text format (RTF) that can be read by any word processing program
  • Flexible customization of user-defined metering instrument data for CTs and VTs speeds up calculation time
  • Exportable simulation curves enable further analysis and even relay testing with regard to CT saturation, especially for systems with high X/R-ratios
  • CT data optimization routines allow for user-defined CT parameters selection suitable for the actual application

CTDim Online Workshops

Are you a new user of CTDim and would like to get to know the main features? Have you recently updated your license to version 3.7 and would like to explore the latest enhancements? In a customized, practical online workshop, learn how CTDim can assist you in optimizing your CT and VT settings. At the same time, you will expand your knowledge and capabilities around instrument transformers, nameplates, and related standards.

Choose from a variety of different workshop formats in the Siemens Industry Mall. The individual contents will be defined upon booking. If you need assistance in selecting the right format, please use our contact form.

CTDim releases

What’s new in CTDim Version 3.7?

  • Technical dimensioning and optimization of selected CTs according to new IEC 61869-2 standard (former IEC 60044-1, IEC 44-6) and ANSI C57.13-2016
  • Detailed calculation tool enabling transient specification of the protective CT cores of class TPX, TPY, TPZ according to the latest IEC 61869-2 / 61869-100 standards
  • Transient simulation for the following classes: 
    IEC: 5P/10P, 5PR/10PR, 5PR (Ts), PX, PXR, TPX, TPY, TPY (Ts) and TPZ
    ANSI: C, T and X
    BS: X
    The results can be exported as Comtrade files 
  • Tools for calculating the maximum through fault current as per the latest IEC 60909-0:2016 standard
  • Protective and measuring device list substantially extended
  • Support for relays with multiple protection functions (ANSI codes)
  • User-friendly manual supports selecting and optimizing process


We are happy to answer all your questions

Looking for a trusted tool to optimize your instrument transformers? Contact us to learn how CTDim can help you to optimally configure your equipment.

Interested in implementing CTDim?

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