Technical Guide P92x/EN CT/E11
IEC 60870-5-103
MiCOM P921-P922-P923 Page 117/118
7. RELAY RE-INITIALIZATION
In case of relay re-initialization, the relay send to the master station :
- A message indicating relay start (INF <5>; TYP <5> COT <6>)
- An identification message of the relay (ASDU 5), which contains the
manufacturer name in 8 ASCII characters et 4 free characters containing :
« P921 » or « P922 » or « P923 ».
8. CYCLIC MESSAGES (ASDU 9 AND ASDU 77)
Only measurands can be stored in these messages.
The measurands values are stored in lower levels of communication, before polling
by master station.
Several of the fields in the ASDU 9 (INF <148>) are unused in the P921/P922/P923
relay (Current and Power values), so they are set to 0 : Only RMS Ua, Ub, Uc values
and frequency are stored (with a rate such as : 2,4 * nominal value = 4096).
Another ASDU, ASDU 77 (INF <149>), which is a private ASDU, contains 3 other
measurands : V0 value, V1 (V direct) and V2 (Vinverse) values, in Volts, and in «short
floating-point » format (IEEE 32 bits floating-point format). These values are not
rated.
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