IDMT Curve Grading

Compare grading margins between two protection relay curves at a specified fault level. Supports IDMT curves with optional definite time elements.

Relay 1 (Upstream)

Curve Type

Is (A)

TMS

Definite Time

DT Pickup (A)

DT Delay (s)

Relay 2 (Downstream)

Curve Type

Is (A)

TMS

Definite Time

DT Pickup (A)

DT Delay (s)

Fault Level (A)

Relay 1 Time

- s

Relay 2 Time

- s

Grading Margin

- s

Grading Curves

Related Protection Tools

IDMT Trip Time Calculator

Calculate trip times for all IEC 60255 curve types.

IDMT Test Comparison

Compare on-site test results against calculated values.

Request a Protection Study

Curves off a calculator are a starting point. A protection study grades the whole chain against the real fault levels, checks equipment duty, and issues the settings tables the DNO and the commissioning engineer will hold you to.