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Operation

Reading the LCD Display

The SDM630MCT-RC features a backlit LCD that cycles through measurement screens. Press the ↑/↓ buttons to navigate manually.

Voltage & Current Screens

Display Parameter Unit
L1-N voltage Phase 1 voltage V
L2-N voltage Phase 2 voltage V
L3-N voltage Phase 3 voltage V
L1 current Phase 1 current A
L2 current Phase 2 current A
L3 current Phase 3 current A

Energy Screens

Display Parameter Unit
Import active energy Total kWh consumed kWh
Export active energy Total kWh generated kWh
Import reactive energy Total kVArh consumed kVArh
Export reactive energy Total kVArh generated kVArh

Power & Power Factor Screens

Display Parameter Unit
Total active power Net power kW
Total reactive power Net reactive power kVAr
Total apparent power Net apparent power kVA
Power factor (per phase) PF L1, PF L2, PF L3 —
Total power factor Overall PF —
Frequency Line frequency Hz

Demand Screens

Display Parameter Unit
Maximum demand Peak power demand kW
Current demand Running demand kW

Interpreting MQTT Telemetry

The Tasmota firmware publishes measurement data via MQTT every TelePeriod seconds (default: 20s).

SENSOR Message

Topic: tele/RS-EMON3P_XXXXXX/SENSOR

{
  "Time": "2026-03-31T14:30:00",
  "ENERGY": {
    "TotalStartTime": "2026-01-01T00:00:00",
    "Total": 15432.56,
    "Yesterday": 123.45,
    "Today": 67.89,
    "Period": 15,
    "Power": 4523,
    "ApparentPower": 4810,
    "ReactivePower": 1187,
    "Factor": 0.94,
    "Voltage": 230.8,
    "Current": 19.6,
    "Frequency": 50.0
  }
}

Key Fields

Field Description Unit
Total Cumulative energy since last reset kWh
Yesterday Energy consumed yesterday kWh
Today Energy consumed today kWh
Period Energy in last TelePeriod interval Wh
Power Instantaneous active power W
ApparentPower Instantaneous apparent power VA
ReactivePower Instantaneous reactive power VAr
Factor Power factor (0.0–1.0) —
Voltage Line-to-neutral voltage (average) V
Current Total current (sum of phases) A
Frequency Line frequency Hz

Monitoring via Home Assistant

When Home Assistant auto-discovery is enabled, the following entities appear:

Sensor Entities

Entity Description Unit
sensor.rs_emon3p_energy_total Total energy kWh
sensor.rs_emon3p_energy_today Today's energy kWh
sensor.rs_emon3p_energy_yesterday Yesterday's energy kWh
sensor.rs_emon3p_power Current power W
sensor.rs_emon3p_voltage Voltage V
sensor.rs_emon3p_current Current A
sensor.rs_emon3p_power_factor Power factor —
sensor.rs_emon3p_frequency Frequency Hz

Creating Dashboards

In Home Assistant:

  1. Go to Settings → Dashboards → Edit
  2. Add cards for energy monitoring entities
  3. Recommended: Energy card, Gauge card for power, History graph for trends

Reading Energy Counters

The SDM630MCT-RC maintains separate counters:

Counter Modbus Register Description
Import active energy 30053–30054 Total kWh purchased from grid
Export active energy 30055–30056 Total kWh exported to grid
Import reactive energy 30057–30058 Total kVArh imported
Export reactive energy 30059–30060 Total kVArh exported
Total active energy 30061–30062 Import + Export

These counters persist through power outages and are stored in non-volatile memory.

Resetting Demand Values

Demand values can be reset via:

  • LCD menu: Navigate to demand screen → hold E button
  • Modbus: Write to register 40001 (value 1 = reset demand)

Power Factor Sign Convention

Power Factor Meaning
+0.0 to +1.0 Inductive load (current lags voltage)
-0.0 to -1.0 Capacitive load (current leads voltage)
1.0 Resistive load (unity power factor)

Most industrial loads are inductive (motors, transformers), resulting in positive PF values typically 0.7–0.95.