electricpy.fault.ct_cclass

electricpy.fault.ct_cclass(XoR, Imag, Irated, CTR, Rb, Xb, remnance=0, sat_crit=20)[source]

Electrical Current Transformer (CT) C-Class Function.

A function to determine the C-Class rated voltage for a CT. The formula shown below demonstrates the standard formula which is normally used to evaluate the saturation criteria. Worth noting here, is the fact that \(V_{rated}\) is the CT C-Class.

\[\text{Saturation Criteria}=\frac{(1+\frac{X}{R})\cdot \frac{|I_{mag}|}{I_{rated}\cdot CTR}\cdot\frac{\left| R_{burden}+j\cdot X_{burden}\right|\cdot100}{V_{rated}}} {1-remnance}\]

For the purposes of this function, the above formula is applied as follows to evaluate the CT C-Class such as to satisfy the saturation criteria defined.

\[\text{CT C-Class}=\frac{(1+\frac{X}{R})\cdot \frac{|I_{mag}|}{I_{rated}\cdot CTR}\cdot\frac{ \left|R_{burden}+j\cdot X_{burden}\right|\cdot100} {\text{Saturation Criteria (i.e., 20)}}}{1-remnance}\]
Parameters:

  • XoR (float) – The X-over-R ratio of the system.

  • Imag (float) – The (maximum) current magnitude to use for calculation, typically the fault current.

  • Irated (float) – The rated secondary current for the CT.

  • CTR (float) – The CT Ratio (primary/secondary, N) to be used.

  • Rb (float) – The total burden resistance in ohms.

  • Xb (float) – The total burden reactance in ohms.

  • remnance (float, optional) – The system flux remnance, default=0.

  • sat_crit (float, optional) – The saturation criteria which must be satisfied, typically such that CT saturation will not occur, default=20.

Returns:

c_class – The calculated C-Class rated voltage.

Return type:

float