Areva MiCOM P125, Technical Manual

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P12y/EN CM/C22 Commissioning and Maintenance
Page 18/24 MiCOM P125/P126 & P127
IEEE/ANSI curves
Type of curve Tripping time (in seconds) for TMS =1
IEEE/ANSI 2 x I threshold 10 x I threshold
Nominal Min - Max Nominal Min - Max
STI 0.25 0.22 - 0.28 0.08 0.07- 0.09
MI 3.8 3.4 - 4.2 1.2 1.08 - 1.32
I 2.2 1.9 - 2.4 0.3 0.27 - 0.33
VI 7.2 6.5 - 8 0.7 0.63 - 0.77
EI 9.5 8.5 - 10.5 0.4 0.36 - 0.44
RI electromechanical curve
Type of curve Tripping time (in seconds) for K =1
Electromechanical 2 x I threshold 10 x I threshold
Nominal Min - Max Nominal Min - Max
RI 4.5 4 - 5 3.2 2.8 - 3.6
For other injected current values, compare the values found with the theoretical values
calculated according to the formula of the curves.
NOTE : Equations of IEC, IEEE/ANSI and RI curves are given in chapter
P12y/EN TD of this Technical Guide.
Checks:
•
I> Alarm message on the LCD display.
•
Alarm LED flashes.
•
Trip LED on
•
I> threshold LED on (if programmed).
•
Trip output closes.
•
I> threshold output closes (if programmed).
4.3.5.3 Phase to phase (phase to neutral) over-voltage U> threshold (P127)
Phase overcurrent threshold check:
•
If tU> time delay is short, gradually raise the injection voltage up to the value of U>
threshold.
•
If U> time delay is long, inject 0.95 x U> threshold setting and check there is no trip.
Then inject 1.1 x U> threshold setting and check the trip output is close.
•
Gradually lower the injected current and note the value of the drop out U> threshold.