As described in the standard and user guide the ASDU 9 measures are stored with a rate such as: 2,4 * nominal value = 4096
It means that value is sent as 16 bit were 13 bits (from 3 to 15) corresponds to the analogue value and 3 bits are reserved (from 0 to 3). The full scale for measurement is 240 percent of the nominal equal to 4096.
Example with the relay setting
0104 Frequency 50Hz
0120 Line CT Primary 1A
0121 Line CT Sec 1A
0124 Line VT Primary 0.10kV
0126 Line VT Sec 100.0V
and injection of 0,5A and 98V.
MiCOM Px2 sends following ASDU 9 frame
68 1A 1A 68 08 01 09 09 02 01 A0 94 20 1A 00 00 00 00 30 34 00 00 30 34 50 15 00 00 50 35 3E 16
Where:
Injection – secondary value injected to the relay
Value max – nominal value in the primary or secondary units
Value from device – hexadecimal value send by the IED
Value in 13 bits – conversion from hex to binary with last 3 bits stripped out
It means that value is sent as 16 bit were 13 bits (from 3 to 15) corresponds to the analogue value and 3 bits are reserved (from 0 to 3). The full scale for measurement is 240 percent of the nominal equal to 4096.
Example with the relay setting
0104 Frequency 50Hz
0120 Line CT Primary 1A
0121 Line CT Sec 1A
0124 Line VT Primary 0.10kV
0126 Line VT Sec 100.0V
and injection of 0,5A and 98V.
MiCOM Px2 sends following ASDU 9 frame
68 1A 1A 68 08 01 09 09 02 01 A0 94 20 1A 00 00 00 00 30 34 00 00 30 34 50 15 00 00 50 35 3E 16
| Injection | Nominal value | Value max corresponding to 4096 (In/Un/Pn/Fn*2,4) | Value from device | Value in 13bits | Value of 13 bits (decimal) | Recalculated value as a part of full scale | |
| Ia | 0,5A | 1A | 2,4 | 201Ah | 0001101000100 | 836 | (836*2,4)/4096 = 0,4898A |
| Ua | 98V | 100V | 240 | 3034h | 0011010000110 | 1670 | (1670*240)/4096 = 97,85V |
| P | 40W | 1x100 = 100W | 240 | 5015h | 0001010101010 | 682 | (682*240)/4096 = 39,96W |
| F | 50Hz | 50Hz | 120 | 5035h | 0011010101010 | 1706 | (1706*120)/4096 = 49,98Hz |
Where:
Injection – secondary value injected to the relay
Value max – nominal value in the primary or secondary units
Value from device – hexadecimal value send by the IED
Value in 13 bits – conversion from hex to binary with last 3 bits stripped out
