MiCOM C264 Bay Controller and GE D25

What it is and where it is used

The MiCOM C264 is a modular bay controller (BCU) for digital substation control systems. It originated in the MiCOM line and is now offered by two manufacturers. GE Vernova also sells it as the DS Agile C264 within its substation control system. Schneider Electric includes it in its PowerLogic line. In that line it is a bay and substation controller, a Smart RTU and a compact solution for medium voltage. It is sometimes called Easergy C264. The GE D25 is an earlier bay controller, from the same period as the D20 RTUs, which is still found in substations.

A bay controller receives the positions of breakers and disconnectors, executes open and close commands, applies interlocks and supervises the bay. GE Vernova highlights it for retrofit projects in existing installations. For the general concept, see the guide to the bay controller.

Variants: C264, DS Agile C264 and D25

Since GE Vernova and Schneider Electric develop the C264 separately, the order number, the software version and the configuration tool are confirmed with the documentation of the corresponding manufacturer.

Main functions

Synchronism check and other functions depend on the version and the cards ordered; confirm them in the datasheet of the installed unit.

Communications and IEC 61850

• IEC 61850-8-1 (MMS and GOOSE) and, in the DS Agile version, IEC 61850-9-2 for sampled values; see IEC 61850 digital substation.
• Dual redundant fiber Ethernet ports.
• Legacy and current communication interfaces to talk to existing equipment and to the control center; as an RTU, the Schneider version integrates through protocols such as IEC 60870-5-104 or DNP3, depending on the configuration.

What the DS Agile C264 brochure says

The following data come from the GE Vernova brochure for the DS Agile C264 (in English, 2025 edition). They correspond to the DS Agile version with the 64-bit CPU4v2; an older C264 with a different CPU may have different limits.

• Roles: the same unit can work as a bay control unit (BCU), as a BCU with protection functions (BCPU), as an RTU, as a switchgear control unit (SCU), as a protocol converter and as a substation gateway.
• RTU capacity: up to 10,000 digital inputs, 1,200 digital outputs, 1,024 analog inputs, 128 counters, 128 setpoints, 128 tap position indications, 8 CTs and 10 VTs. It supports up to 15 independent acquisition racks communicating over Ethernet, up to four simultaneous SCADA connections and up to 16 IEDs per RS-485 serial interface.
• Digital inputs: five types (single, double, multiple, system and logic combination), all with 1 ms time stamping and filters for debounce, persistence, motion and undefined state. An input can be suppressed, substituted or manually forced to invalid, something that must be recorded and reviewed before the installation is handed over.
• Commands: select-before-operate once (SBO once), select-before-operate many (SBO many) and direct execute. SBO many is used for transformers (tap raise and lower). It is covered in select-before-operate.
• Interlocks: two methods, by logic equations or by topology with predefined rules; the conditions are shown on screen so the operator can see what prevents an operation.
• Trip circuit supervision: two- or four-wire options; with four wires, continuity is supervised both with the breaker closed and open.
• Reclosing: one reclosing function per bay, single-phase or three-phase, up to four cycles with independent timing, initiated internally or by an external protection (79 auto-reclosing).
• Voltage regulation: the AVR function governs one transformer or up to four in parallel, with compensation at a remote point, ratio adjustment before connecting to a busbar and, for parallel operation, circulating current minimization or master-follower.
• Programmable logic: PSL, event-oriented with no cycle time, for fast automation, and an optional IEC 61131-3 PLC for complex sequences. It applies to automatic transfers, system integrity protection schemes and load shedding.
• Recording: sequence of events of up to 2,048 events with 1 ms resolution, of which 200 are shown on the local display; fast and slow waveform records in binary COMTRADE 2001 (COMTRADE files).
• Measurement: RMS values, frequency, angle, powers, power factor, sequence components, derivatives and harmonic distortion up to the 15th harmonic.

Network and process

The unit has six independent Ethernet ports for two separate LANs, for example the station bus and the remote SCADA, with a native switching application that manages VLANs. The ports can act as a RedBox to connect non-PRP devices to a redundant network, and optional switches with PRP and HSR (IEC 62439-3) are offered. The brochure also describes a dual access point to separate the station bus from the process bus. It also describes sampled value handling according to IEC 61850-9-2 and the transmission of binary signals in under a millisecond by GOOSE, with dynamic selection of the voltage reference. With embedded CTs and VTs, a single controller can manage two bays and publish sampled values.

For time synchronization it supports operator, IRIG-B, SNTP, IEEE 1588 PTPv2 and the remote SCADA through DNP3 or IEC 60870-5; it can also act as an SNTP server. On cybersecurity, GE Vernova announces role-based access control, local authentication, security event logging, a password policy and compliance with the BDEW whitepaper. It also announces a secure development lifecycle certified to IEC 62443-4-1:2018. It further states that the unit provides the capabilities needed to build a solution compliant with IEC 62443-3-3:2013. Whether the final solution complies depends on its complete design; see IEC 62443 in substations.

Commercial status

The C264 catalog page on the GE site indicates that the CPU4 remains available. It has more processing capacity and memory than the CPU3 and six Ethernet ports. It also indicates that orders for new projects with the earlier version were accepted until May 31, 2024, with the CPU4 as the alternative. The installed-base figures given by the manufacturer are commercial data that we have not independently verified. In a retrofit project, it is worth recording in writing the CPU and software version of the unit to be replaced.

Frequently asked technical questions

• MiCOM C264 technical manual in PDF: each manufacturer publishes its own; the GE Vernova one does not apply as is to a Schneider C264, or the other way round.
• Closing is blocked: almost always an interlock that is not met, an inconsistent disconnector position or a GOOSE message that does not arrive; the case is covered in GOOSE does not arrive or arrives late.
• System database: in DS Agile systems, the C264 configuration is part of a database for the whole substation; changing one controller in isolation without updating it creates inconsistencies.
• Replacing a D25: the replacement is not direct; the inputs and outputs, the logic and the integration change.

If your equipment is no longer manufactured

The GE D25 is no longer manufactured. GE Vernova points to the C30 or C60 for bay controller applications; a C264 or another controller can also be considered, depending on the substation architecture. In any case, the existing signals must be surveyed, the logic and interlocks redone and the new unit integrated into SCADA. We design the replacement and test it before energizing, as described in engineering design and studies. The fault recorders and PMUs from Qualitrol, GE Vernova and SEL are compared in Fault Recorders: Qualitrol BEN 6000 and Reason RPV311.

How we help

Our team configures MiCOM C264 bay controllers: control logic and interlocks, IEC 61850 integration or integration with SCADA through telecontrol protocols, and functional tests of the bay. We load and modify the logic, interlocks and signals remotely, worldwide, with the remote configuration of relays and controllers, without waiting for a site visit. The wider scope is in control, protection and communications configuration and IEC 61850 engineering. For a quote, write to us through contact.

Related guides

• Bay controller (BCU)
• Substation RTU and gateway
• GE Multilin UR feeder relays (F60, C60, C30)
• MiCOM P14x relay
• Substation SCADA and HMI system
• SEL-451 controller
• IEC 61850: overview
• SIPROTEC 6MD85, 6MD86 and 6MD6 bay controller
• ABB REC670, REC650 and REC615 bay controller
• GE Multilin D20, D400 and G500 RTU and gateway
• Ingeteam INGEPAC EF CD and ZIV IRF bay controller
• GOOSE interlocking with CILO and CSWI (IEC 61850)
• Control levels in substations and the local/remote selector
• Select-before-operate (SBO): how control works
• Fault Recorders: Qualitrol BEN 6000 and Reason RPV311

References

• GE Vernova, MiCOM C264 product page, DS Agile C264 brochure and legacy gateways and RTU catalog (D25).
• Schneider Electric, MiCOM C264 range page (PowerLogic).
• IEC 61850 (series), communication networks and systems for power utility automation.

Frequently asked questions