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.
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|