The interchangeable part of the IEC 60870-5-103 standard defines that only five Class 2 measurands frames exist. Measurands transmitted in these five Class 2 frames relates to current and voltage values only. The allowed scale factors, actually meaning |max values| of per unit coded measurands, are 1.2 or 2.4. The IEDs support all five interchangeable Class 2 measurand frames defined by the standard.
| Frame number | ASDU | FUN | INF | Num of data | Data in the Class 2 frame |
|---|---|---|---|---|---|
| 1 | 3 | 0 | 144 | 1 | IL2 |
| 2 | 3 | 0 | 145 | 2 | IL2, U12 |
| 3 | 3 | 0 | 146 | 4 | IL2, U12, P3, Q3 |
| 4 | 3 | 0 | 147 | 2 | Io, Uo |
| 5 | 9 | 0 | 148 | 9 | IL1, IL2, IL3, UL1, UL2, UL3, P3, Q3, f |
1 FUN = 0 means that the Function type is coded as the Device function type which in turn is defined by the setting parameter DevFunType n.