P92x/EN CT/E11 Technical Guide
Modbus Protocol
Page 66/118 MiCOM P921-P922-P923
CODE DESCRIPTION
F72 Conversion rules for the voltage values of the frequency disturbance record
* In ordre to obtain the phase voltages values at the VT primary, apply the
following formula:
“Read value” x (“VT primary value” / “VT secondary value”) x Internal ratio
numerator
*In order to obtain the Vo value at the residual VT primary, apply the following
formula:
“Read value” x (“Residual VT primary value” / “Residual VT secondary value”) x
Internal ratio numerator
Internal ratio numerator=100/internal ratio denominator
Internal ration denominator=6300 for the range(57-130V) or 1700 for the
range(220-480V)
Measured frequency= 1000000/measured cycle
F73 Frequency disturbance record data
1st Word: disturbance record end time (sec – MSB)
2nd Word: disturbance record end time (sec – LSB)
3rd Word: disturbance record end time (msec – MSB)
4th Word: disturbance record end time (msec – LSB)
5th Word: Cause of frequency disturbance trigger :
Control Commande order for Starting frequency disturbance record
Specific logic input: Start disturbance record
Time delayed information of a logic equation
Closing of the tripping contact (RL1)
6th Word: Frequency at the beginning of Post-time
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