Saroj Joshi, PE, Ph.D./ Co-Authors: David Quezada, PE /Renas Shwany Ray/James Sherwin /Kristine Cayanan.
Without training in fieldwork and extensive practical pieces of knowledge, we consider engineering education incomplete and scary. Today we want to give an example of the Characteristics of the breakers and their testing.
For example, say molded case electromagnetic breakers :
We got a chance to learn about testing breakers in the field. Most of the engineering colleges will give limited practical knowledge showing physical breakers panels etc. Students will have access to books and manufacturer catalogs and you can learn a lot about theoretical aspects.
When we are talking about the testing of the breakers right in the field most likely no college will have that level of practical classes.
Long time delay and Instaneous testing of the breakers:
We got a chance to learn more about electromagnetic breakers of 400A, 225A, and 100A 3-phase breakers and tested them at the NETA level recently. We got enlightened to test breakers at different levels such as overload, and instances testing.
Long-time delay testing:
All testing shall be done per manufacturer table that concerns required testing by certified testing companies approved / Licensed by NETA or equivalent.
Table of the overload testing (long time delay) of their available types of breakers. Load-breaking amps will be usually 300% times the breaker rating. Say the breaker size is 15A then load breaking amps ( testing Amps) will be about 45A then if the breaker trips within the recommended time per table say it is within 3.3 to 23 seconds. If breakers trip within the range stated above then breakers testing is successful.
The testing company must have a license/certification for testing from the National Electrical Testing Association (NETA).
Instantaneous testing :
Testing amps will be usually 10-20 times the breaker ratings and must comply with the table below the table for 15A where breakers' Instantaneous current A is 300A and trip time range is within 0 to 0.013 seconds If the broker's trip as stated above means testing is successful and the breaker is approved by NETA.
All testing will be done at low voltage by NETA an approved instrument.
For advanced electronic breakers, there will be different testing for different levels of settings such as LSIG ( long time delay (overload), short circuit, instantaneous, and Ground fault. All testing must comply with the manufacturer-recommended table and successful testing per NETA requirements.
Conclusion:
One can have elite knowledge of breakers but without practical knowledge of testing as we have experienced and without hands-on practice we consider education incomplete. So we highly recommend having hands-on practice in the concerned field for all the engineers.
Note: We would like to extend our cordial thanks to the experts, who contributed to us with their valuable time and teachings on the above subject.
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