Complete range of transformer monitor products — PT100 winding temperature controllers (BWDK-326 series) for dry-type transformers, fluorescent fiber optic hot spot measurement systems for oil-immersed power transformers, and intelligent multi-parameter condition monitoring devices.
A transformer monitor is an electronic device or integrated system that continuously measures, displays, and logs the critical operating parameters of a power transformer — most importantly winding temperature and oil temperature — and automatically controls cooling fans while triggering alarm and trip outputs whenever safe limits are exceeded.
Modern transformer monitor devices fall into two main technology families:
1. PT100 Resistance Temperature Controllers — the industry-standard solution for dry-type transformers. Sensors are embedded in the A, B, C phase windings and the controller (such as the INNO BWDK-326 series) provides winding temperature display, cooling fan control, over-temperature alarm, and trip relay output.
2. Fluorescent Fiber Optic Hot Spot Systems — the advanced solution for high-voltage oil-immersed power transformers. Armored fiber optic sensors directly measure winding hot spot temperature with 100% EMI immunity, 140 kV high-voltage isolation, and 25+ year calibration-free operation.
Both types connect to SCADA, BMS, and DCS platforms via RS485 Modbus RTU, 4-20mA analog, or IEC 61850 communication protocols. A properly specified transformer monitor extends asset life by 20–30%, prevents catastrophic insulation failure, and enables condition-based maintenance in place of costly time-based inspection.
Overheating is the single leading cause of transformer failure and shortened service life. Once winding insulation begins to degrade thermally, the damage is irreversible — yet it builds silently, invisible to periodic inspection until a costly failure occurs.
Thermal defects between scheduled checks can evolve into catastrophic failure. A continuous transformer monitor provides real-time visibility with instant alarm output.
Winding hot spots can exceed average oil temperature by 20–30°C. Without direct measurement via PT100 or fiber optic transformer monitor sensors, hot spots remain undetected.
Condition-based maintenance guided by real-time transformer monitor data reduces emergency repairs and significantly extends transformer asset life.
INNO dry-type transformer monitor devices use embedded PT100 platinum resistance sensors to continuously measure three-phase winding temperatures. The controller displays real-time maximum temperature, automatically controls cooling fans, and triggers alarm and trip outputs to protect transformer insulation from overheating.
Oil-immersed transformers require both winding hot spot temperature measurement (WTI) and top oil temperature monitoring (OTI). INNO provides traditional oil-filled winding temperature indicators, digital oil thermometers, and advanced fiber optic direct hot-spot measurement systems — all with SCADA integration and relay alarm outputs.
Both sensing technologies serve distinct transformer monitor applications. Understanding their strengths helps you select the optimal device for your transformer type and installation environment.
| Monitoring Criterion | PT100 RTD Sensor | Fluorescent Fiber Optic | Best For |
|---|---|---|---|
| Primary Application | Dry-type transformer winding monitoring | Oil-immersed transformer hot spot | Application-specific |
| Temperature Range | −30°C ~ 240°C | −40°C ~ 260°C | Fiber optic for extreme ranges |
| Measurement Accuracy | ±1% FS (Class B) | ±1°C absolute | Fiber optic for critical hot spots |
| EMI Immunity | ⚠ Susceptible in high-field environments | ✔ 100% EMI Immune | Fiber optic in high-voltage environments |
| High-Voltage Isolation | ⚠ Requires isolation barrier | ✔ 140 kV withstand (glass fiber) | Fiber optic for HV transformer windings |
| Installation in Oil | ⚠ Not suitable inside oil-filled windings | ✔ Armored probes for direct winding embed | Fiber optic for oil-immersed windings |
| INNO Recommendation | BWDK-326 Series — Dry-type transformer monitor | Fiber Optic System — Oil-immersed transformer monitor | Contact us for assessment |
| Communication Output | RS485 Modbus, 4-20mA, Relay | RS485 Modbus, IEC 61850, 4-20mA | Both support SCADA/BMS integration |
| Sensor Lifetime | 10–15 years (recalibration needed) | 25+ years (calibration-free) | Fiber optic for long-term TCO |
| Cost | More economical | Higher initial investment | PT100 for large dry-type fleets |
Full-range transformer monitor devices engineered for utility substations, industrial facilities, OEM transformer manufacturers, and project buyers. Factory-direct pricing, bulk order support, private-label OEM available.
The PHM online monitoring system delivers comprehensive real-time health assessment for dry-type transformers in power substations and rail transit. It integrates temperature, partial discharge, vibration, arc detection, humidity, and smoke monitoring — communicating via IEC 61850 fiber optic network to station-level SCADA systems.
Three-channel winding temperature monitor controller with automatic fan control, over-temperature alarm, and trip protection. Available with RS485, 4-20mA, and ambient/core temperature sensor options.
Advanced microcontroller-based temperature monitor for dry-type transformer winding protection. Features digital display, self-diagnostic function, and flexible communication interfaces.
Comprehensive state monitor for dry-type transformers. Tracks temperature, load current, and operating status in real time to provide a complete health picture for condition-based maintenance.
Panel-mounted temperature control box for dry-type transformers. Integrates winding temperature detection, cooling fan management, and alarm relay in a compact enclosure.
Specially designed temperature monitor for rectifier transformers, furnace transformers, and other non-standard transformer types requiring customized monitoring configurations.
Compact and cost-effective winding temperature controller for standard dry-type distribution transformers. Reliable PT100-based monitor with essential alarm and fan control functions.
Complete INNO dry-type transformer monitor catalog — BWDK-326 series, BWDK-S3206, BWDK-PQ201, BWD-3KR control boxes, state monitors, and intelligent PHM systems. Factory-direct with OEM support for bulk orders and transformer manufacturers.
Traditional winding temperature indicator with oil temperature sensor for oil-immersed power transformers. Monitors winding hot spot temperature rise, controls cooling fans, and triggers alarm and trip relay outputs.
Standard top-layer oil temperature indicator (OTI) for oil-immersed transformers. Analog pointer display with built-in alarm contacts for over-temperature protection.
Digital version of the oil temperature indicator with LCD display, 4-20mA analog output, and RS485 communication. Combines oil level and temperature measurement in a single instrument.
Integrated monitor device that simultaneously tracks top oil temperature, oil level, and oil pressure in oil-immersed transformers with SCADA integration.
Complete INNO oil-immersed transformer monitor catalog — WTI winding temperature indicators, OTI oil temperature indicators, digital BWY-D804 thermometers, and multi-parameter oil condition monitoring systems for utility and industrial project buyers.
Direct winding hot spot measurement using fluorescent fiber optic probes pre-embedded in dry-type transformer windings.
High-precision fiber optic hot spot monitor for oil-immersed power transformers — armored probes withstanding 140 kV and long-term oil immersion.
Purpose-designed armored probe sensor for permanent installation inside oil-immersed transformer windings. Withstands full submersion in transformer oil at high voltage.
End-to-end fiber optic temperature measurement solution including sensors, multi-channel transmitters, software and communication for both transformer types.
Temperature monitoring is the foundation of transformer health assessment. For critical power transformers, INNO also provides supplementary online monitoring systems for complete condition visibility.
Detects and continuously tracks partial discharge activity within transformer insulation. Early identification of insulation defects before they develop into dielectric failure.
Continuously analyzes dissolved gases in transformer oil to detect thermal faults, partial discharge, and arcing in real time. Triggers alarm when gas levels exceed IEEE/IEC thresholds.
Online monitoring of bushing capacitance and tan delta values to detect moisture ingress, insulation degradation, and mechanical defects before failure.
INNO's comprehensive transformer monitoring solution integrates temperature, DGA, partial discharge, bushing, OLTC, and oil condition monitoring into a unified online platform.
Key specifications for INNO's primary transformer monitor products. Custom specifications, channel counts, and communication interfaces available on request.
| Product Series | BWDK-326 Series |
| Temperature Range | −30.0°C ~ 240.0°C |
| Ambient Temperature | −20°C ~ +55°C |
| Ambient Humidity | <95% (at 25°C) |
| Working Voltage | AC 220V (+10%, −15%) |
| Working Frequency | 50Hz or 60Hz (±2Hz) |
| Measurement Accuracy | ±1% FS (Class 0.5 thermostat / Class B sensor) |
| Resolution | 0.1°C |
| Sensor Type | PT100 Platinum Resistance Temperature Sensor |
| Fan Output Capacity | 5A / 250VAC |
| Control Output Capacity | 5A / 250VAC; 5A / 30VDC (resistive) |
| Power Consumption | ≤8W |
| Housing Dimensions | 160mm × 80mm × 120mm (W × H × D) |
| Communication (Optional) | RS485 Modbus RTU / 4-20mA / IEC 61850 |
| Production Standard | JB/T 7631 |
| Certifications | CE · RoHS · ISO 9001 · EMC IEC 61000-4 |
| Product Type | Fluorescent Fiber Optic Transformer Temperature Measurement System |
| Temperature Range | −40°C to +260°C (customizable to +300°C) |
| Measurement Accuracy | ±1°C (±0.5°C high-accuracy version available) |
| Resolution | 0.1°C |
| Response Time | <1 second |
| Sensor HV Insulation | 140 kV withstand voltage |
| Channel Options | 1 / 3 / 4 / 6 / 9 / 16 / up to 64 channels |
| Communication | RS485 Modbus RTU / 4-20mA / IEC 61850 |
| Sensor Lifetime | 25+ years, calibration-free |
| EMI Immunity | 100% immune — glass fiber, no electronics at probe tip |
| Oil Submersion | Armored versions rated for permanent transformer oil immersion |
| Certifications | CE · RoHS · ISO 9001 · ISO 14001 · ISO 45001 |
INNO transformer monitor devices are deployed globally across every industry where reliable transformer operation is critical to safety and productivity.
110kV and above power transformers requiring continuous online monitoring in grid substations.
Zero-downtime dry-type transformer monitoring for critical IT infrastructure power supply.
PHM intelligent monitoring for traction substations in urban metro and rail transit systems.
Dry-type transformer monitor devices protecting electrical systems in large buildings.
Step-up transformer monitoring for wind farms and solar power plant substations.
Heavy-duty transformer protection for manufacturing plants, steel works, and refineries.
Dry-type transformer temperature monitoring for airport power distribution systems.
Life-safety grade transformer monitoring where any power interruption has immediate consequences.
INNO designs, manufactures and calibrates every transformer monitor, sensor, and transmitter at our own facility in Fuzhou, Fujian, China — giving you full product traceability, OEM flexibility, and factory-direct competitive pricing with no distributor markup.
Every BWDK controller, PT100 sensor, fiber optic system, and intelligent monitoring device is manufactured in-house at our Fuzhou factory. Full quality control and no distributor markup on every order.
INNO holds expertise in both PT100 resistance-based temperature controllers for dry-type transformers and patented fluorescent fiber optic measurement for oil-immersed transformer hot spot monitoring.
Products certified to CE, RoHS, ISO 9001, ISO 14001, ISO 45001, EMC IEC 61000-4, and Chinese industry standard JB/T 7631. Full documentation available on request.
Private-label branding, custom firmware, tailored probe geometries, special communication protocols, and application-specific monitoring configurations — all supported.
INNO transformer monitor devices are field-deployed in substations, airports, metro systems, and industrial facilities across more than 50 countries.
Fluorescent fiber optic transformer monitor installed on power transformers in a major substation, delivering real-time winding hot spot data.
INNO dry-type transformer monitor controllers deployed across airport power distribution dry-type transformers.
Comprehensive dry-type transformer monitor solution deployed across multiple traction substations.
Fluorescent fiber optic hot spot monitor system installed on dry-type transformer winding at an industrial facility.
Integrated oil condition monitor for comprehensive oil-immersed transformer condition assessment.
Fiber optic transformer monitor controllers deployed for winding temperature monitoring in a rail transit power supply system.
Answers to the most common questions about dry-type and oil-immersed transformer monitor products and applications.
Looking for an end-to-end solution rather than individual monitor devices? Explore our dedicated transformer and substation monitoring solution pages.
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