Timestamped mains outages
Every outage and restore is logged with its duration, ~3 s debounce.
Power Monitor
Mains and temperature monitor – outages and climate in real time
Cabinet and room surveillance: Timestamped mains outages · Temperature and humidity under alarm · 0.42" OLED display · web portal · MQTT publishing (SCADA) · 3D-printed enclosure · UPS power
Key features
What you see, what you keep
The Power Monitor shows power and climate status on site and pushes every event to your supervision.
Temperature and humidity under alarm
Min/max thresholds with hysteresis: the alarm goes out over MQTT the moment a limit is crossed — no nuisance trips at the setpoint.
0.42-inch OLED display
Time, network, message, humidity and temperature at a glance — readable even while the sensor is warming up.
Web configuration portal
WiFi, MQTT, thresholds and timezone set from your phone: automatic hotspot or .local address, nothing to install.
MQTT publishing for SCADA
Status, climate, events and alarms published under SCADA/<device>/… : your supervision consumes the readings as they are.
3D-printed enclosure, ready to mount
Ventilated shell, sprung battery bay and clip rail: it sits on UPS in minutes.
Specifications
Power Monitor technical specifications
| Processor | ESP32 |
|---|---|
| Display | 0.42-inch OLED |
| Climate sensor | Temperature and humidity sensor (auto-detected) |
| Clock | Battery-backed RTC (optional) or NTP |
| Mains detection | Optocoupler on GPIO — never a direct connection |
| Debounce | ~3 s — micro-outages are filtered |
| Log | Outages in non-volatile memory + RTC timestamps |
| Connectivity | WiFi + MQTT — topics SCADA/<device>/… |
| Configuration | Web portal — 192.168.4.1 or <device>.local |
| Power | 5 V USB-C from the UPS — keeps running through outages |
| Enclosure | 3D-printed — vented, battery bay, clip rail |
Outage log
Every outage found again — even after a total blackout
Every outage and every restore is timestamped, with the event duration and a counter: you know exactly when the power went out and how long it was gone.
The event is written to non-volatile memory: even a total power loss of the unit cannot lose the incident.
When the network returns, the whole log is published over MQTT — your supervision picks up the events with no manual step.
UPS power
Sitting on UPS, it keeps watch when everything stops
Powered by UPS, the Power Monitor keeps monitoring during the outage — it is the device that tells you how long it lasted.
The sprung battery bay takes the supplied cell: open in one gesture, replace with no tools and no enclosure disassembly.
The vented shell clips onto the cabinet rail — logic-side opto isolation, never a direct connection to the mains.
Benefits
Why choose the Power Monitor?
You will know when the power went out
Timestamps, durations and counters: no more “we had no idea” when a machine wakes up wrong the next morning.
Alarms arrive on their own
Temperature and humidity thresholds, hysteresis against nuisance alarms, immediate MQTT publication — nobody has to chase anything.
Installed in minutes
Opto isolation on the GPIO, clip rail and web portal: the installation stays simple and isolated, with no programmer.
Built for the shop floor
Tough box, BOOT button = portal in one press, readable display — the unit lives right among the machines.
FAQ
Frequently asked questions
Mains presence is measured on a GPIO through an optocoupler: never a direct connection between the mains and the logic. A debounce of about 3 s filters micro-outages.
The event is written to non-volatile memory and the RTC keeps the time: on reboot, the unit finalizes the interruption with its exact duration.
Yes. The auto-detected temperature sensor reads temperature and humidity: min/max thresholds with hysteresis, alarm published over MQTT, readings every 60 s — the first 5 minutes stay hidden while the sensor warms up.
Everything is published over MQTT under SCADA/<device>/…: status, climate, events and alarms — your SCADA tools consume the readings as they are.
Through the web portal: automatic hotspot (192.168.4.1) or existing network, then WiFi, MQTT, thresholds and timezone configured via .local. A long press on BOOT reopens the portal.
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Cabinet, server room or generator: we size the Power Monitor and the MQTT pipeline within 24 hours.