Description
Product Overview
1MRK002122-ABr03 is the revision-03 build of the short-range optical line data communication module used inside ABB Relion 670 terminals, the board the product guide lists as “Optical short range LDCM” and the factory marks 670LDCM02 SHORT. Mechanically it is a plug-in card for a remote-communication position in a RED670, REG670, REL670, RET670 or REC670 chassis; functionally it is the physical layer of a line differential scheme, exchanging sampled currents between two ends across a single duplex multimode fiber pair.
The payload explains the design. Each 5 ms the module emits a telegram carrying three-phase current samples, the time reference that keeps the two terminals aligned, trip and block flags, alarms, and eight binary signals that can be assigned to transfer trip or interlocking. Because the differential algorithm compares samples taken at the same instant, framing continuity and clock discipline on this board determine whether the protection remains stable through a fault — a fact that turns an optical link into a protection setting.
Reach is a property of the glass and the budget, not of the terminal. With 62.5/125 µm graded-index fiber the board carries 13 dB of optical budget and roughly 3 km; on 50/125 µm it offers 9 dB and about 2 km. Minimum launch is −17 dBm, receiver sensitivity −30 dBm, and a high-power setting adds approximately 3 dB where the route approaches its limit. Used against those figures, the documented loss assumptions of 3 dB/km, 1.5 dB per ST connector and 0.5 dB per repair splice let an engineer decide feasibility from a route survey rather than from a trial installation.
Technical Specifications
表格
| Parameter | Value |
|---|---|
| Model | 1MRK002122-ABr03 |
| Hardware revision | r03 (board type identical to r05 and r09) |
| Manufacturer | ABB, Sweden |
| Product type | Line data communication module, optical short range, IED plug-in board |
| Optical interface | ST duplex, separate transmit and receive fibers |
| Fiber | Graded-index multimode 62.5/125 µm standard; 50/125 µm supported |
| Wavelength | 820 nm peak emission, 865 nm nominal, 792 nm minimum |
| Optical budget | 13 dB on 62.5/125 µm, 9 dB on 50/125 µm |
| Distance capability | Approximately 3 km and 2 km, subject to link calculation |
| Output and sensitivity | −17 dBm minimum launch on 62.5/125 µm; −30 dBm receiver sensitivity |
| Protocol | IEEE C37.94 synchronous with HDLC framing |
| Data rate | 64 kbit/s standard, 2 Mbit/s mode selectable |
| Channel capacity | Up to four LDCM channels per IED |
| Telegram content | Three-phase currents each 5 ms, time reference, trip/block/alarm, eight binary signals |
| Power supply | Derived from the IED backplane; no external feed |
| Slot assignment | P30:5, P30:6, P31:3, P32:2 or P32:3 depending on case configuration |
| Standards | IEC 60255-26 EMC, IEC 60255-1 and IEC 60255-27 for the parent IED |
1MRK002122-ABr03
Key Features and Advantages
Reach is set by the fiber, not by adding hardware
Where both ends of a protected line sit inside one compound or one industrial site, 1MRK002122-ABr03 closes the loop with multimode glass alone. No single-mode transceivers, no FC/PC fusion splicing, no telecom lease, and no optical attenuators on short spans once the low-power setting is applied — the accessories that usually inflate a short-haul differential project simply do not appear in the bill.
One pair of fibers carries currents, trips and interlocking
The eight binary signals travelling inside the current telegram replace the separate teleprotection channel that older schemes required. Transfer trip, busbar-to-line interlocking and status exchange all inherit the same supervision, the same alarm handling and the same route documentation, which also halves the number of fiber pairs to be maintained and tested.
Topology is a matter of module count
Four remote-communication positions per chassis mean a three-ended line can terminate two channels at each end, and a redundant arrangement can run a main and standby path that the signal matrix fails over automatically. 1MRK002122-ABr03 supports those topologies without a second communication processor, an external changeover unit, or a separate cabinet.
Clock roles and power level fixed at commissioning
One terminal generates the timing and the other derives it from the incoming signal; the high or low optical power level is chosen from the measured route loss. Both decisions are made once, recorded in the commissioning file, and remain stable — which is why a channel that behaves correctly on the day it is set up usually stays correct until a connector or a patch cord changes.
Applications
Two-substation schemes within a single fence are the everyday case: a 400 kV yard paired with its 110 kV counterpart, a hydro station switchyard tied to the adjacent grid node, or two bays protecting a short interconnecting feeder. The span is short, the fault current is not, and 1MRK002122-ABr03 delivers unit protection over glass that costs a fraction of a single-mode route.
Cascade hydro plants along one river often sit a kilometer or two apart, and each successive pair of REG670 terminals can be linked with this board rather than with a leased circuit. Urban distribution networks use the same approach between neighboring substations on cable circuits, where the physical run is short but an uncleared fault translates directly into customer minutes lost.
Industrial captive systems form another group — mine feeder lines, steel plant interties, refinery internal transmission, airport and data-centre HV distribution — where a private network spanning a few kilometers needs the same unit protection a utility applies to a transmission line. Teleprotection-only schemes also specify the board: interlocking between busbar and line protection, transfer trip from external relays, or status exchange for a sequential black-start, all travelling on the supervised pair.
Test bays and training installations complete the picture, connecting two terminals back to back over a short multimode patch cord to prove the differential function end to end before the scheme is energized.
Related Products
1MRK002311-AA — medium range LDCM, single-mode 9/125 µm at 1310 nm with FC/PC connector, 22 dB budget covering the 60 to 80 km class. 1MRK002311-BA — long range LDCM at 1550 nm on single-mode fiber, 26 dB budget for 110 to 130 km links. 1MRK005500-AA — Ethernet SFP module, optical LC connector, for station bus traffic rather than the protection channel. 1MRK005500-BA — Ethernet SFP module with RJ45 connector, the copper version of the same station-bus option. 1MRK002266-EA — optical Ethernet module for IEC 61850 station communication. 1MRK001608-AB / 1MRK001608-BB / 1MRK001608-CB — serial SPA, LON, DNP and IEC 60870-5-103 modules in plastic, plastic-glass and glass variants. 1MRK002309-AA — galvanic RS485 module for short copper links within a station. 1MRK007002-AA — GPS time module where the differential function is synchronized from a global reference instead of the channel. 1MRK002282-AB — IRIG-B synchronization module, the alternative external time base. RED670 / REG670 / REL670 — terminals in which 1MRK002122-ABr03 is installed.
Installation and Maintenance
Before installation: read the revision marking on the board label and record it, because 1MRK002122-ABr03 is an earlier build than the r05 and r09 units generally found in newer chassis, and a maintenance file that does not distinguish them loses traceability after the first swap. Confirm the chassis offers a free remote-communication position at P30:5, P30:6, P31:3, P32:2 or P32:3, count the channels the scheme requires, sweep the route with an optical time-domain reflectometer, and compare the measured loss against the 13 dB budget before deciding the power setting. Isolate the IED, then fit the board and keep patch cords to the installed fiber specification.
Maintenance practice: clean every ST ferrule before mating and after any work at the distribution panel, since a single dirty end face can absorb more budget than the entire aging allowance. Log launch power and received level at commissioning and re-measure annually — a 2 to 3 dB shift points to connector wear rather than to a failing module. After any board change, confirm the clock master and slave roles between the two ends, run a loop-back test, and read the channel supervision counters before releasing the protection. Store spare 1MRK002122-ABr03 units with optical port caps fitted and the revision level visible.
Warranty and Quality
1MRK002122-ABr03 ships as a plug-in module with its revision level stated on the label and repeated in the packing documentation, so the receiving engineer knows exactly which build is going into which position. Each unit is verified on a fiber loop-back bench for launch power, received level, frame lock and channel status before dispatch, and the measurement record accompanies the shipment. A 12-month warranty applies under standard substation-automation practice, covering repair or replacement for quality-related failure. Technical support covers slot assignment, master and slave clock configuration, budget review against route survey data, and the choice between low and high optical power settings.
