siemens
Siemens SIPROTEC 7XA85 IEC 61850-9-2 Merging Unit
Model: 7XA8500-0BA00-0AA0
4-hour response · Pricing in SAR · Delivery across all KSA regions
7XA8500-0BA00-0AA0 — Siemens SIPROTEC 7XA85 IEC 61850-9-2 Merging Unit
The Siemens SIPROTEC 7XA85 is the process-bus merging unit that digitises the analogue output of conventional current and voltage instrument transformers and transmits instantaneous sample values over IEC 61850-9-2 to SIPROTEC and other IED protection relays, forming the foundation of a modern IEC 61850 process bus architecture that eliminates copper wiring between the primary apparatus bay and the protection relay cubicle. Each 7XA85 converts up to eight CT inputs and four VT inputs to 80 sampled values per cycle IEC 61850-9-2 LE streams — the digital equivalent of the conventional CT/VT wiring harness that traditionally runs from switchgear to protection relays.
Eliminating hardwired CT/VT wiring cables from the switchgear bay to the relay room delivers major project benefits in Saudi substations: cable reduction of 30–50% in a large 220/33 kV primary substation, elimination of CT circuit-resistance errors in long cable runs common in Saudi 380/220 kV outdoor substations, and complete elimination of CT open-circuit hazard during secondary testing. Multiple IEDs can simultaneously subscribe to a single merging unit's SV stream, allowing duplicate main protection, backup protection, metering, and recording IEDs to share a single set of instrument transformer measurements without additional CT/VT burdens — impossible with conventional hardwired systems.
In Saudi Arabia, the 7XA85 is specified by SEC for new 380/220/110/33 kV primary substations and major substation extensions under IEC 61850 process-bus architecture projects. The 2030 National Transformation Programme's acceleration of transmission and distribution capacity addition makes process bus architecture an increasing share of Saudi substation projects — NEOM, Red Sea Project, and Qiddiya substations are being designed as fully digital IEC 61850 substations where the 7XA85 process-bus architecture replaces conventional hardwired bay protection.
Razz Middle East supplies 7XA85 merging units with IEC 61850 configuration, GOOSE testing, and SIPROTEC 5 Digsi 5 engineering support for Saudi substation projects.
Technical Specifications
Full specifications for the 7XA8500-0BA00-0AA0
- Inputs
- 8× CT, 4× VT (analogue)
- Sampled Values
- IEC 61850-9-2 LE (80 samples/cycle at 50 Hz)
- Subscribers
- Unlimited IED simultaneous subscription
- Synchronisation
- IEEE 1588 PTP / GPS
- Communication
- 2× 100 Mbit Ethernet (process bus)
- Enclosure
- 1/6 19" rack or bay-mount
- Power Supply
- 24–250 V DC
- Standard
- IEC 61850-9-2, IEC 61869
Key Features & Benefits
- IEC 61850-9-2 LE sampled value streaming at 80 samples per cycle provides the digital equivalent of conventional CT/VT hardwiring, enabling subscription by protection, metering, and recording IEDs simultaneously.
- Cable reduction of 30–50% versus conventional CT/VT wiring in large 220/33 kV substations, reducing project material cost, installation time, and cable tray congestion in switchgear buildings.
- Elimination of CT open-circuit hazard during secondary testing and maintenance work removes a significant safety risk present in all conventional hardwired CT secondary circuits.
- Multiple IED subscription to a single SV stream allows main protection, backup protection, metering, and disturbance recording to share one physical CT/VT set without additional transformer burdens.
- IEEE 1588 PTP synchronisation maintains sub-microsecond time accuracy across the process bus, ensuring sampled value streams from multiple merging units remain time-coherent for differential protection calculations.
- IEC 62439-3 Parallel Redundancy Protocol (PRP) or RSTP ring redundancy provides fault-tolerant process bus communication with zero recovery time for IEC 61850 protection applications.
- Digsi 5 engineering tool integration provides unified configuration of the 7XA85 and connected SIPROTEC 5 IEDs within the same engineering environment, reducing configuration and testing time for process-bus projects.
Industrial Applications in Saudi Arabia
- SEC 380/220/110 kV primary substation new builds under IEC 61850 process-bus architecture, where 7XA85 merging units replace all conventional CT/VT wiring between switchgear bays and relay room.
- NEOM and Red Sea Project transmission and distribution substations designed as fully digital IEC 61850 substations, where process bus architecture satisfies the projects' smart infrastructure specifications.
- ARAMCO large industrial substation extensions, where process bus retrofitting with 7XA85 allows IEC 61850 protection relay upgrades without replacing the existing primary switchgear instrument transformers.
- Saudi desalination facility 115/13.8 kV substations at SWCC and MARAFIQ plants, where process bus architecture reduces protection relay wiring while simplifying protection relay replacement during future upgrades.
- Qiddiya and entertainment city utility substations, where fully digital IEC 61850 process-bus architecture eliminates future rewiring during protection system upgrades.
- SEC grid automation projects requiring centralised protection, where multiple protection IEDs subscribing to the same merging unit SV stream provides fault-tolerant redundant protection without additional primary measurement equipment.
- Industrial microgrid substations for Vision 2030 smart city projects, where the 7XA85 process bus architecture provides the digital foundation for microgrid protection and energy management integration.
Industrial Supplier in Saudi Arabia
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