Support CT Saturation Calculator


CT SAT Calculator Ideally, we select CTs that normally operate in their linear region. In practice, CT saturation is unavoidable. With a better modeling of CT saturation in an existing system, protection engineers can optimize their relay settings and understand the behavior of the relay under such conditions.

This program is intended to show large current or high burden behavior only; it does not accurately represent the conditions at the low-end portion of the iron saturation curve. Consequently, hysteresis loss and eddy current loss are not modeled because they have negligible effect on the saturation region behavior.

ANSI/IEEE guidelines provide equations that assist to determine appropriate conditions of CT saturation. Below are spreadsheets, which our customers may find helpful to determine:
  • whether or not a CT will saturate in particular situation (such as heavy primary current, CT burden variation etc.)
  • an accurate indication of the actual waveshape of the secondary current (predicted degree of saturation at each point in time)
Data may then also be input to a digital relay, by converting it into a COMTRADE file.



Data may then also be used to play-back into the microprocessor based Relays/Recorders using a test set (system), which supports the COMTRADE file play-back capability.

Terms of Use

ERLPhase Power Technologies Ltd. shall not be held responsible for any damages or losses that could result, directly or indirectly, in whole or in part from the usage of the CT SAT Calculator programs. You agree to indemnify, defend and hold harmless ERLPhase Power Technologies Ltd. and its affiliates and their officers, directors, employees, contractors, agents, licensors, service providers, subcontractors and suppliers from and against any and all losses, liabilities, expenses, damages and costs, including reasonable attorneys' fees and court costs, arising or resulting from your use of the program.


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Winnipeg, Canada