Galvanically Isolated Temperature Sensing for Power Distribution Systems
In high-voltage environments such as power distribution systems, temperature monitoring plays a critical role in ensuring system reliability and preventing thermal overloads. Components like bolted connections, copper busbars, and terminal blocks can develop hot spots over time due to resistive heating, poor connections, or environmental stress. To detect these issues early and maintain operational safety, localized temperature sensing is essential—yet measuring temperatures at different electrical potentials poses a significant challenge.
An additional advantage of using Pinier’s isolated sensor modules is that power only needs to be supplied on the low-voltage (SELV) side. No auxiliary power is required at the sensor (high-voltage) side, simplifying installation and improving system reliability.
The Role of Galvanic Isolation in Temperature Sensing
When monitoring temperatures on live components at different voltage levels (e.g., between phases or from ground), standard temperature sensing techniques cannot be used directly due to the risk of electrical shock or equipment damage. Galvanic isolation breaks the direct electrical path between the sensor side and the measurement side, allowing safe and accurate temperature monitoring, even across multiple potential domains.
NTC Thermistors: Simple, Robust, and Proven
A common and effective solution for temperature measurement in these scenarios is the use of Negative Temperature Coefficient (NTC) thermistors. NTCs are:
- Robust and compact, suitable for tight electrical enclosures and on-surface mounting
- Reliable, with predictable resistance-to-temperature behavior
- Cost-effective, making them ideal for large-scale deployment
These sensors can be embedded in ring lugs or thermally conductive epoxy and mounted directly to bolted joints or busbars, providing fast and responsive readings.
No External Signal Conditioning Required
Thanks to the integrated Wheatstone bridge and signal processing within the isolator, there is no need for external signal conditioning or linearization circuitry. This simplifies the overall system design and ensures consistent, calibrated output signals from the sensor module.
Application Examples
- Monitoring high-current bolted connections in LV/MV switchgear or inverter cabinets
- Temperature tracking of DC busbars in battery systems or UPS units
- Overheat protection for power distribution, where sensors are installed on critical joints
Each of these applications involves components at different voltages. By integrating a signal isolator between the thermistor signal and the data acquisition system, accurate readings can be transmitted safely to the control or monitoring system.
System Architecture
A typical setup includes:
- NTC thermistor mounted to a live component
- High-voltage signal isolator
- DAQ system or PLC input
This configuration ensures complete isolation between the sensing point and measurement electronics, preventing common-mode errors, signal interference, and potential safety hazards.
Why Use Pinier Signal Isolators
Pinier Engineering offers high-isolation, compact modules ideal for industrial temperature monitoring. Our isolators are designed to:
- Handle high common-mode voltages reliably
- Offer excellent accuracy and signal stability over time
- Integrate easily with standard 4–20 mA or voltage output sensing circuits
Conclusion
Monitoring temperature in high-voltage systems is critical—and achievable—when galvanic isolation is properly implemented. Paired with rugged NTC sensors, isolated temperature sensing provides an efficient and scalable way to detect thermal issues early in power distribution environments.