According to IEC 61869 standard, ENMU belongs to a class of Stand-Alone Merging Units. 

ENMU analog inputs are connected to electromagnetic instrument transformers. ENMU digitizes analog signals and broadcasts streams of IEC 61850-9-2LE sampled values (SV) over Ethernet. 

ENMU is connected with optical fiber to the process bus and time synchronization source. The SV streams are broadcasted to intelligent electronic devices (IEDs): digital protective relays, power meters, revenue and power quality meters, phasor measuring units. ENMU publishes up to 4 SV streams. 

ENMU complies with IEC 60870-5-104 and IEEE C37.118.2 communication protocols. In other words, ENMU can act as a phasor measurement unit (PMU). Moreover, ENMU archives synchrophasor data and records oscillographic fault data.

ENMU is equipped with three 100Base-FX ports, two of which can provide redundancy using PRP as of IEC 62439. Third Ethernet port can be implemented as a 100Base-FX or 100Base-T.

Time synchronization is carried out from ENCS-2 time sync module. ENMU receives time synchronization signals via PTPv2 (IEEE 1588 v.2) over Ethernet, or from a 1 PPS/ IRIG-A/ IRIG-B time source through dedicated interface implemented as a 100Base-FX, or RS-485 port.

ENMU is a unique three-in-one device that combines merging unit, phasor measurement unit, and fault recorder functionality. 

ENMU can be implemented upon request with different types of analog inputs.


Connection instrument transformers and protection circuits, 4 measurement (M) and 3 protection (P) current inputs, 4 voltage inputs
Rated values/operating range current (M): 1 or 5 A / 1–200 %, current (P): 1 or 5 A / 10-4000 %, line voltage: 100 V / 5–200 %, frequency: 50 Hz / 40–60 Hz
Synchronization source IEEE 1588v2 PTP or IRIG-A/IRIG-B/PPS through ST fiber optic
Accuracy 0.2 DR 1–200, 2TPS, 0.2
Sampling rate 4800 and 12800 Hz (80 and 256 samples per nominal period)
Digital inputs 16 isolated high-voltage (3.75 kV) binary inputs, with programmable upper and lower input thresholds
Digital outputs 10 relays of which 7 are form A relays (6 A 250 VAC, 10 ms operate, 5 ms release) and 3 are solid state relays (3.5 A 250 VDC, 5 ms operate, 0.2 ms release)
Interfaces up to 4 × Ethernet 100Base-FX LC, up to 2 × Ethernet 100Base-T 2 × RS-485, 1 × CAN
Redundancy IEC 62439-3 PRP
Communication protocols IEC 61850-9-2 LE streaming, IEEE C37.118.2, IEC 60870-5-104, FTP, IEC 61850-8-1 (MMS, GOOSE)
Extension modules analog inputs and digital inputs/outputs: up to 240 external I/O units; up to 8192 analog values, 4096 binary signals, 2048 commands
Power supply 120–370 V DC / 100–240 V AC (45–55 Hz), 15 VA
Operating conditions & mounting from −40 to +70 °C / 303 х 254 х 94 mm, IP40