Sampled Values
IEC 61850-9-2 digital representation of voltage and current waveforms, multicast from merging units to subscribing IEDs at 4 kHz (protection) or 12.8 kHz (metering).
Also: SV, 9-2 LE, Sampled Values protocol
Sampled Values are the digital representation of voltage and current waveforms, transmitted from merging units at the process level to IEDs at the bay level over the substation process bus.
Sample rates
| Application | Samples per cycle | Rate at 50 Hz | Rate at 60 Hz |
|---|---|---|---|
| Protection (9-2 LE) | 80 | 4,000 Hz | 4,800 Hz |
| Power quality / metering | 256 | 12,800 Hz | 15,360 Hz |
Protection-grade SV at 50 Hz produces a frame every 250 µs. The receiving IED has microseconds, not milliseconds, to do anything meaningful.
Multicast and timing
SV is publish/subscribe Ethernet multicast on the substation LAN. Because the receiver consumes streams from multiple merging units and reconstructs current and voltage phasors from their relative timing, every merging unit on the bus has to share the same time reference — typically PTP under the IEC/IEEE 61850-9-3 Power Utility Profile, sub-microsecond accuracy.
SV is not synchrophasors
Both are timestamped electrical measurements but they operate at different scales for different purposes. SV is the local-protection digitisation of waveforms inside a substation; synchrophasors (IEEE C37.118) are wide-area phasor measurements at 30-120 frames per second for grid-level situational awareness.
Security
SV crosses the same authentication gap as GOOSE and is addressed by the same IEC 62351-6 embedded-HMAC mechanism. The per-frame budget is even tighter than for trip GOOSE — microseconds rather than milliseconds — which is why AES-GMAC was added in the 2020 edition specifically for this context.