Description
Product Overview
1MRK002122-ABr12 is a late-build revision of the short-range optical line data communication module used in ABB Relion 670 terminals — catalogued as “Optical short range LDCM”, marked 670LDCM02 SHORT at the factory, and distinguished from the medium and long range variants by its -AB suffix. It is a plug-in card for a remote-communication position in a RED670, REG670, REL670, RET670 or REC670 chassis, and it exists for one purpose: to carry the sampled currents of a line differential function between two terminals over a single duplex multimode fiber pair.
Its output every 5 ms is a telegram containing three-phase current samples, the time reference that aligns the two ends, trip and block indications, alarms and eight binary signals that can be assigned to interlocking or transfer trip. Because the differential algorithm compares values taken at the same instant, the framing and clock behaviour of this card sit directly inside the protection performance envelope — the reason it is documented as protection hardware rather than as a communication accessory.
Where the board can be used, and where it cannot, is an arithmetic question. Graded-index 62.5/125 µm glass yields 13 dB of budget and roughly 3 km of reach; 50/125 µm yields 9 dB and about 2 km. Launch is −17 dBm minimum, receiver sensitivity −30 dBm, and a high-power setting contributes about 3 dB. Against the standard assumptions of 3 dB/km, 1.5 dB per ST mating and 0.5 dB per repair splice, those figures settle feasibility for a given station pair before any hardware is released.
Technical Specifications
表格
| Parameter | Value |
|---|---|
| Model | 1MRK002122-ABr12 |
| Hardware revision | r12, latest-level build in the sequence observed in service |
| Manufacturer | ABB, Sweden |
| Product type | Optical short range line data communication module, IED plug-in board |
| Optical interface | ST duplex, transmit and receive pair |
| Fiber specification | Graded-index multimode 62.5/125 µm standard; 50/125 µm accepted |
| 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 |
| Reach | Approximately 3 km and 2 km respectively, by link calculation |
| Launch and sensitivity | −17 dBm minimum output on 62.5/125 µm; −30 dBm receiver sensitivity |
| Protocol | IEEE C37.94 synchronous, HDLC framing |
| Data rate | 64 kbit/s default, 2 Mbit/s mode selectable |
| Telegram payload | Three-phase currents each 5 ms, time reference, trip/block/alarm, eight binary signals |
| Channels per terminal | Up to four remote communication interfaces |
| Power supply | From the IED backplane, no separate feed |
| Slot positions | P30:5, P30:6, P31:3, P32:2, P32:3 by chassis variant |
| Compliance | IEC 60255-26 EMC, IEC 60255-1 and IEC 60255-27 for the parent IED |
1MRK002122-ABr12
Key Features and Advantages
A build level changes the supply chain, not the signal
Nothing in the r12 marking alters modulation, framing, optical budget or the 5 ms telegram — those are properties of the -AB type. What a later build affects is component sourcing and process maturity, which is the part that matters when a chassis built fifteen years ago needs a working module rather than a museum piece. Treating 1MRK002122-ABr12 as the same product, with a different date, keeps specification documents and protection settings unchanged through a replacement.
One fiber pair with two jobs to do
The eight binary signals travel inside the current telegram, so transfer trip, busbar-to-line interlocking and status exchange come free of any second channel. In a station where the fiber distribution panel is already congested, that consolidation removes a pair of ports and a pair of terminations from the change scope, and it removes a second set of failure modes from the scheme.
Budget arithmetic that keeps multimode viable
Thirteen decibels is enough for most intra-site and adjacent-substation routes, and knowing that number precisely is what prevents an unnecessary migration to single-mode optics with FC/PC terminations and fusion splicing. 1MRK002122-ABr12 is therefore selected on a measured route loss and a documented aging margin, not on a nominal distance figure copied from a datasheet.
Instrumentation built into the module
Launch power is adjustable in two steps, the receiver reports its level, and the channel exposes supervision counters through the terminal. A maintenance team can therefore distinguish a dirty connector from a failing card from a disturbed clock relationship without pulling the module — the diagnostics that shorten a fault-finding visit on a channel nobody can see.
Applications
Station pairs inside a compound remain the largest application group: an EHV yard and its lower-voltage counterpart sharing a fence line, a generating station switchyard adjacent to the grid substation, or two bays protecting a short tie feeder. The fiber distance is trivial, the protection duty is identical to a long line, and 1MRK002122-ABr12 supplies unit protection without introducing single-mode components into the project.
Fleet sustainment is the second and increasingly common use. Terminals commissioned a decade or more ago still run differential schemes, and a late-build module is what keeps a channel in service when the original card fails — with the protection settings, signal matrix and clock roles restored from the stored parameter set rather than re-engineered.
Industrial plants with a captive HV network use the board where two nodes sit within a few kilometers: a smelter tied to its own substation, a refinery with an outlying distribution point, a port or data-centre campus with a dedicated HV ring. Cascade hydro stations apply it between successive REG670 terminals along the same river reach, and urban cable networks between adjacent distribution substations.
Schemes that carry binary signals only also specify it — interlocking, remote trip from external protection, or status exchange for a sequential black-start — as do test departments proving a differential pair back to back on the bench.
Related Products
1MRK002311-AA — medium range LDCM, single-mode 9/125 µm at 1310 nm, FC/PC connectors, 22 dB budget for roughly 60 to 80 km; a distance tier, not a successor. 1MRK002311-BA — long range LDCM at 1550 nm with 26 dB budget, for 110 to 130 km routes; the upper tier of the same family. 1MRK005500-AA — Ethernet SFP module, optical LC connector, serving IEC 61850 station bus traffic. 1MRK005500-BA — Ethernet SFP module, RJ45 connector, the copper station-bus option. 1MRK002266-EA — optical Ethernet module for station communication on the same platform. 1MRK001608-AB / 1MRK001608-BB / 1MRK001608-CB — serial SPA, LON, DNP and IEC 60870-5-103 modules in plastic, plastic-glass and glass versions. 1MRK002309-AA — galvanic RS485 module for short copper links inside a station. 1MRK007002-AA — GPS time module where the differential function is clocked globally rather than from the channel. 1MRK002282-AB — IRIG-B synchronization module, the alternative external time base. RED670 / REG670 / REL670 — terminals hosting 1MRK002122-ABr12 in line differential, generator and distance protection.
Installation and Maintenance
Before installation: verify that the free position is a remote-communication slot at P30:5, P30:6, P31:3, P32:2 or P32:3 for the chassis variant in question, then count modules against the scheme — one for a two-ended line, two per end for a three-ended line, a main and standby pair for redundancy. Take an optical time-domain reflectometer survey of the route rather than trusting as-built drawings, compare the loss with the 13 dB budget, and choose the power setting from the resulting margin. Isolate the IED, record the revision marking of the outgoing and incoming 1MRK002122-ABr12 in the asset file, and keep patch cords on the same glass specification as the route.
Maintenance practice: clean ST ferrules at each mating and after every intervention at the fiber panel. Log launch and received levels at commissioning, re-measure annually, and treat a 2 to 3 dB decline as connector or splice degradation rather than a card fault. After a substitution, restore the channel configuration, verify clock master and slave roles at the two ends, run a loop-back test and read the supervision counters before release. Because late builds are the ones most likely to remain obtainable, holding one spare 1MRK002122-ABr12 against critical channels avoids a redesign caused by a single failed card.
Warranty and Quality
1MRK002122-ABr12 is supplied as a plug-in module with the revision level printed on the label and repeated in the packing documentation, so the position it fills is recorded from the moment it arrives. Each unit passes a fiber loop-back verification covering launch power, received level, frame lock and channel status, and the measurement sheet ships with it. A 12-month warranty applies under standard substation-automation practice, covering repair or replacement for quality-related failures. Where a scheme spans several modules, sets are checked for revision consistency before dispatch. Technical support covers slot mapping, clock role configuration, budget review from survey data and the low or high power decision, and it can advise on spares holding for a mixed-age terminal fleet.
