Appendix B: Wiring Diagrams¶
3-Phase 4-Wire (3P4W) — Primary Configuration¶
This is the default and most common configuration for commercial/industrial installations with a neutral conductor.
Connections¶
| Terminal | Connection | Description |
|---|---|---|
| 1 | Phase L1 | Voltage measurement |
| 2 | Phase L2 | Voltage measurement |
| 3 | Phase L3 | Voltage measurement |
| 4 | Neutral N | Voltage reference |
| 5 | Auxiliary Live | Meter power supply |
| 6 | Auxiliary Neutral | Meter power supply |
| 15–16 | CT1 on L1 | Rogowski coil Phase 1 |
| 17–18 | CT2 on L2 | Rogowski coil Phase 2 |
| 19–20 | CT3 on L3 | Rogowski coil Phase 3 |
Notes¶
- All 4 voltage terminals connected (L1, L2, L3, N)
- 3 Rogowski coils required (one per phase)
- Measures: V, A, W, VA, VAr, PF, kWh per phase + totals
3-Phase 3-Wire (3P3W)¶
Used in systems without a neutral conductor (delta configuration).
Connections¶
| Terminal | Connection | Description |
|---|---|---|
| 1 | Phase L1 | Voltage measurement |
| 2 | Phase L2 | Voltage measurement |
| 3 | Phase L3 | Voltage measurement |
| 4 | Not connected | — |
| 5 | Auxiliary Live | Meter power supply |
| 6 | Auxiliary Neutral | Meter power supply |
| 15–16 | CT1 on L1 | Rogowski coil Phase 1 |
| 17–18 | CT2 on L2 | Rogowski coil Phase 2 |
| 19–20 | Not connected | — |
Notes¶
- Only 3 voltage terminals connected (L1, L2, L3)
- 2 Rogowski coils required (CT1 + CT2)
- CT3 not used
- Set system type to 3P3W in meter configuration
1-Phase 2-Wire (1P2W)¶
For single-phase installations.
Connections¶
| Terminal | Connection | Description |
|---|---|---|
| 1 | Phase L | Voltage measurement |
| 2 | Not connected | — |
| 3 | Not connected | — |
| 4 | Neutral N | Voltage reference |
| 5 | Auxiliary Live | Meter power supply |
| 6 | Auxiliary Neutral | Meter power supply |
| 15–16 | CT1 on L | Rogowski coil |
| 17–18 | Not connected | — |
| 19–20 | Not connected | — |
Notes¶
- Only terminal 1 (L) and terminal 4 (N) connected
- 1 Rogowski coil required (CT1 only)
- Set system type to 1P2W in meter configuration
Auxiliary Power Wiring¶
The meter requires auxiliary power independent of voltage measurement inputs.
| Terminal | Connection |
|---|---|
| 5 | Live (85–277V AC, 50/60Hz) |
| 6 | Neutral |
Note: Auxiliary power can be sourced from any phase or a dedicated supply. The meter starts up within 3 seconds of power application.
RS485 Daisy-Chain Wiring¶
For installations with multiple meters on the same Modbus bus:
Master ────[D+ D-]──── Meter 1 ────[D+ D-]──── Meter 2 ────[D+ D-]──── Meter N
| |
└── 120Ω ────────────────────────────────────────────────────────────── 120Ω ──┘
Requirements¶
- Cable: Twisted pair (minimum 22 AWG), shielded for industrial environments
- Topology: Linear daisy-chain (no star or T-taps)
- Termination: 120Ω resistor at each physical end of the bus
- Max length: 1200 meters total bus length
- Max devices: 32 meters per bus segment
- Addresses: Each meter must have a unique Modbus address (register 40071)
General Wiring Notes¶
- Wire gauge: Use appropriately rated wire for the current being measured. For voltage inputs and auxiliary power, minimum 1.5mm² (14 AWG) is recommended.
- Cable glands: Use appropriately sized cable glands on the HT-8WAY enclosure to maintain IP rating.
- CT polarity: Rogowski coil arrow must point in the direction of current flow (source → load).
- Isolation: RS485 is galvanically isolated from voltage/current inputs.
- Grounding: Connect RS485 shield (terminal 11) to ground at one point only to avoid ground loops.