Distribution Feeder Protection & Control Unit Reference Design
An illustrative distribution feeder protection & control unit design for switchgear, ring main units and distribution substations: AC/DC 110 / 220V universal supply, dual 100M Ethernet ports (station bus A / B networks, IEC 61850 / Modbus TCP), isolated RS-485 (Modbus RTU), IRIG-B time sync, synchronous AC voltage / current sampling, binary inputs and trip relay outputs. This page covers the function, selection notes and VOOHU part numbers for 32 component positions.
Illustrative PCB ⇄ Schematic
The schematic layout shows placement and component positions; click any position for selection notes, recommended parts and package. The board is a schematic arranged by functional zone (not the actual layout), with the CPU, AC input, binary I/O and power modules drawn on one board; Ethernet ports, communication and time-sync terminals, sampling terminals, binary I/O terminals and the power terminal sit on the bottom edge, while PT / CT and the circuit breaker are external nodes.
The station-bus network A and B ports are identical; only 1 port and 1 differential pair are drawn (the other 100M pair is the same). RJ45 J1 / J2 are plain jacks without magnetics, followed by discrete VOOHU 100M LAN transformers T1 / T2 (WHSH16F01D4, 4800 Vrms isolation); on the PHY side the ESD arrays D1 / D2 (WHALD03G4U) clamp the lines before the JL1101BR 100M PHYs, whose RMII links go to the two MACs of the main processor for IEC 61850 / Modbus TCP traffic. Follow the PHY datasheet for center-tap connection, termination and crystal load capacitors.
Board bill of materials
Click any row to jump to that position and view its selection notes
| No. | Zone | Position | Ref. | VOOHU category | Recommended part | Availability |
|---|---|---|---|---|---|---|
| 01 | A Ethernet ×2 | RJ45 port ×2 (station bus A / B) | J1 J2 | RJ45 Connectors | SYT561188AB1A1DB4 | VOOHU |
| 02 | A Ethernet ×2 | 10/100 LAN transformer ×2 | T1 T2 | 10/100 LAN Transformers | WHSH16F01D4 | VOOHU |
| 03 | A Ethernet ×2 | Ethernet ESD array ×2 | D1 D2 | TVS / ESD | WHALD03G4U | VOOHU |
| 04 | A Ethernet ×2 | 100M PHY ×2 (RMII) | U1 U2 | Ethernet PHY | JL1101BR-NI | VOOHU |
| 05 | A Ethernet ×2 | PHY 25MHz crystal ×2 | Y1 Y2 | — | — | Non-VOOHU |
| 06 | B RS-485 · Time Sync | RS-485 communication terminal | J3 | — | — | Non-VOOHU |
| 07 | B RS-485 · Time Sync | Gas discharge tube (stage 1) | G1 | GDT | WHGT090V1P0A | VOOHU |
| 08 | B RS-485 · Time Sync | Bus TVS (stage-2 clamp) | D3 | TVS / ESD | WHALD30E2B | VOOHU |
| 09 | B RS-485 · Time Sync | Bus differential-line common-mode choke | L1 | Signal Line CMC | WHAC-4532A-601T0 | VOOHU |
| 10 | B RS-485 · Time Sync | Isolated RS-485 transceiver | U3 | — | — | Non-VOOHU |
| 11 | B RS-485 · Time Sync | IRIG-B time-sync terminal | J4 | — | — | Non-VOOHU |
| 12 | B RS-485 · Time Sync | Time-sync line TVS | D4 | TVS / ESD | WHALD30E2B | VOOHU |
| 13 | B RS-485 · Time Sync | IRIG-B isolated receiver | U4 | — | — | Non-VOOHU |
| 14 | B RS-485 · Time Sync | Push-pull isolated power transformer ×2 | T3 T4 | Push-Pull Transformers | WHST06K14A0 | VOOHU |
| 15 | B RS-485 · Time Sync | Push-pull driver ×2 | U5 U6 | — | — | Non-VOOHU |
| 16 | C Sampling · Binary I/O | AC sampling terminal | J5 | — | — | Non-VOOHU |
| 17 | C Sampling · Binary I/O | Miniature PT / CT (power frequency) | T5 T6 | — | — | Non-VOOHU |
| 18 | C Sampling · Binary I/O | Simultaneous-sampling ADC | U7 | — | — | Non-VOOHU |
| 19 | C Sampling · Binary I/O | Binary input terminal | J6 | — | — | Non-VOOHU |
| 20 | C Sampling · Binary I/O | BI optocoupler | U8 | — | — | Non-VOOHU |
| 21 | C Sampling · Binary I/O | Trip relay ×2 | K1 K2 | — | — | Non-VOOHU |
| 22 | C Sampling · Binary I/O | Binary output terminal | J7 | — | — | Non-VOOHU |
| 23 | D Core | Main processor (dual MAC) | U9 | — | — | Non-VOOHU |
| 24 | D Core | Memory (DDR / Flash) | U10 | — | — | Non-VOOHU |
| 25 | D Core | MCU crystal | Y3 | — | — | Non-VOOHU |
| 26 | D Core | Core supply filter molded inductor ×2 | L2 L3 | Molded Inductors | WHYTA0420 Series | VOOHU |
| 27 | E Device Power | Device power input terminal | J8 | — | — | Non-VOOHU |
| 28 | E Device Power | Input protection (fuse · MOV · X capacitor) | RV1 | — | — | Non-VOOHU |
| 29 | E Device Power | Isolated AC/DC power module | PS1 | — | — | Non-VOOHU |
| 30 | E Device Power | +24V output power-line CMC | L4 | Power Line CMC | WHAL-7060A-102T0 | VOOHU |
| 31 | E Device Power | Synchronous buck ×2 (24V→5V→3.3V) | U11 U12 | — | — | Non-VOOHU |
| 32 | E Device Power | DC-DC molded inductor ×2 | L5 L6 | Molded Inductors | WHYT0630 Series | VOOHU |
Resources & downloads
Board bill of materials
Reference designators, zones, VOOHU categories, recommended parts and availability for all 32 positions. Opens directly in Excel.
Datasheet collection
Datasheet PDFs for the VOOHU parts recommended on this board.
Design files & footprint library
Schematic, PCB, and VOOHU part footprints and 3D models.
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Includes the BOM, datasheets of recommended VOOHU parts and per-position selection notes. For advice on your port count, communication protocols or isolation requirements, describe them in the request. We reply within 24 hours on working days.
