This is an android application for aiding electrical engineers who work for Utility companies and building services engineering consultancies to quickly perform design and checking calculations on IEEE C37.112 IDMT relays without the need of gaining any internet connection. It allows you to investigate the disconnection time of the relay for various North American relay characteristics - M.I., V.I., E.I., C08, P20 and P40.

Four functions are offered in this tool:
1. Calculation of relay operation time where you will enter the TMS Setting, the Fault current magnitude (If) and the relay current setting (Is) - this is the most common method used by protection engineers
2. Calculation of relay operation time where you will enter the Time disconnection Setting (TDS), the Fault current magnitude (If) and the relay current setting (Is)
3. Calculation of relay operation time where you will enter the Time disconnection (TD/7) setting, the Fault current magnitude (If) and the relay current setting (Is)
4. Calculation of secondary injection current value into the CT where you will enter the CT Primary, CT Secondary and the relay current setting (Is) - it will give you the recommended injection current value into the secondary of the CT

This App is mainly for protection engineers who use IEEE C37.112 relays. If your work does involve IEC relays, please consider Dr Tony Sung Electrical Services Calculator #1 package instead.

In this release, we have implemented many error catching subroutines to avoid crashes. Please email us if you come across any error using the feedback page at start-up of the app. Thank you.