Embedded Energy

HEMS — Genset Monitoring & Remote Cut-off

IoT monitoring and remote cut-off board for 3-phase gensets (400/230 V, 25–200 kVA). One ATM90E36A metering IC reads the full electrical picture — voltage, current, power, power factor, frequency, energy, and power quality — streamed over ESP32-S3 Wi-Fi to the cloud. Remote cut-off disconnects non-paying rental units, with an energize-to-block fail-safe that keeps paying customers running even if the board loses power. A single board runs on 12 V or 24 V batteries with 3 kV galvanic isolation, and an engine-sensor expansion bus extends it to fuel, vibration, oil, and RPM. First device on the HEMS platform.

Domain
Embedded Energy
Technology
ATM90E36A · ESP32-S3 · HEMS Platform · 3-Phase Metering · Remote Cut-off · IoT Telemetry · Energy Monitoring
The HEMS Platform

HEMS — the Heavy Equipment Monitoring System — is Avenxor’s platform for putting mission-critical machines online. The genset monitor is its first device: one board that turns any rented or owned genset into a connected, billable, remotely controllable asset. The same cloud, dashboard, and engine-sensor bus extend to the wider fleet next.

System Capabilities
01
Full Electrical Metering
One ATM90E36A IC reads voltage and current per phase plus neutral, active/reactive/apparent power, power factor, and frequency — the complete 3-phase picture from a single chip, no external meter.
02
Energy Accounting (kWh)
Four-quadrant energy: active import/export (kWh), reactive (kvarh), and apparent (kVAh). Billing-ready totals per unit, ideal for genset rental and pay-per-use models.
03
Power Quality & Protection
THD and harmonics (orders 2–42), plus SAG detection, phase loss, reversed phase sequence, and over/under conditions — surfaced as alerts before they damage the load.
04
Remote Cut-off
Disconnect a genset over the air for overdue rentals. Energize-to-block logic is fail-safe: if the board loses power, the paying customer’s genset stays running.
05
Engine-Sensor Expansion
A spare I/O bus extends the board to battery voltage, fuel level, MEMS vibration, oil temperature/pressure, and RPM — the bridge from genset to wider heavy-equipment monitoring.
06
Wi-Fi Cloud + OTA
ESP32-S3 streams telemetry to the cloud over Wi-Fi and accepts over-the-air firmware updates. Programmable over USB-C — even with no battery connected.
07
3 kV Galvanic Isolation
The mains-referenced metering side and the battery-referenced logic side are fully isolated through a certified digital barrier and isolated DC-DC — safe by design.
08
Universal 12 V / 24 V
A single PCB runs on both 12 V and 24 V genset batteries — the mode is selected by fuse position, no separate SKU, no jumper guesswork.
09
Non-Invasive Current Sensing
A 333 mV Rogowski coil clamps onto the existing cable — no panel rewiring, anti-saturation, and one design covers the full 100–200 kVA range via software calibration.
What One IC Reads

The ATM90E36A metering IC delivers the entire 3-phase electrical picture over SPI — no separate transducers, no per-parameter modules. The firmware reads these registers, calibrates in software, and streams the result to the cloud.

Voltage & Current
RMS per phase (A/B/C) + neutral current
Power
Active (W) · Reactive (var) · Apparent (VA), per phase & total
Power Factor
PF per phase & total, plus voltage–current phase angle
Frequency
Grid frequency (Hz) from the voltage channel
Energy
Active import/export (kWh) · reactive 4-quadrant (kvarh) · apparent (kVAh)
Power Quality
Voltage & current THD and harmonics (orders 2–42)
Protection
SAG · phase loss · reversed sequence · over/under · start-up surge
Fleet Dashboard
HEMSGenset Fleet · 6 Units
▲ 1 Alarm⏻ 1 Cut-off● 5/6 Online
MQTT · TLS · OTA09:41:22
GEN-01150 kVA● RUNNING
Tower A · Jakarta
LOAD98kW
VOLT398V
FREQ50.0Hz
PF0.89cos φ
FUEL72%
1,240 kWh
GEN-02200 kVA● ALARM
Mall B · Bekasi
LOAD186kW
VOLT392V
FREQ49.6Hz
PF0.82cos φ
FUEL8%
2,110 kWh
⚠ LOW FUEL 8% · OVERLOAD 93% · UNDER-FREQ 49.6 Hz
GEN-03100 kVA● RUNNING
Site C · Karawang
LOAD54kW
VOLT401V
FREQ50.0Hz
PF0.91cos φ
FUEL45%
760 kWh
GEN-04125 kVA● CUT-OFF
Rental D · Cikarang
⏻
Disconnected — overdue payment
GEN-05150 kVA● IDLE
Plant E · Serang
LOAD4kW
VOLT399V
FREQ50.1Hz
PF0.70cos φ
FUEL88%
1,530 kWh
GEN-0680 kVA● OFFLINE
Depot F · Tangerang
No signal
Hardware
Genset Range
25–200 kVA
3-phase 4-wire · 400/230 V · 50 Hz
Metering Core
ATM90E36A
32-bit SPI · poly-phase energy metering IC
Compute
ESP32-S3
Wi-Fi · Cloud · OTA · USB-C native flash
Battery Input
12 V / 24 V
Single PCB · fuse-selectable mode
Isolation
3 kV
Galvanic barrier between metering & logic
Current Sensor
333 mV
Non-invasive Rogowski coil, clamp-on
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[email protected]Jakarta, Indonesia
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