Helping the mining industry grow in a sustainable wayLearn more
Energy education from anywhere for efficiency everywhereFree Online Courses
Your fastest way to answers!Download Now
Schneider Electric Egypt×
The maximum current values come under the maximeter function of Micrologic.
Each second, there is a routine which update all maximeters. Of course only if the present value is higher than the background of the maximeter.
In addition each 20 ms the current RMS values are transferred from the ASIC to the microcontroller, for this reason the refresh time can be 1s +20ms/- 0ms.
>> For instantaneous current maximeters all Micrologic A/P/H, the trip unit keeps held the maximum value except if the current value comes greater or if you do a reset.
>> The maximeter (peak value's display) is the result of the RMS calculation done from the sampling achieved in annex A.
But you have to take into account the time constant of the maxi meter processing =>
the maxi meter has a time constant at about 550 ms, it is the same approach as a RC filter.
That means the maxi meter display 63% of the total current variation after 550ms and 95% of the total current variation after 5 time 550ms (2.75 s).
For example if the current rise suddenly from 100A to 500 A the delta is 400A and after 550 ms the current displayed by the maxi meter is about 350 A(100+ .63x 400) and after 2.75 s at about 480 A.