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Switchgear Temperature Monitoring

temperature monitoringOSENSA’s cost-effective fiber optic temperature sensors provide continuous real-time monitoring of switchgear temperature at critical contact points to quickly detect overload and fault conditions. OSENSA’s FTX series temperature transmitters offer both analog output and RS-485 Modbus communication for simple integration with existing PLCs (Programmable Logic Controllers) and host monitoring software. OSENSA’s optical temperature sensors provide years of accurate sensing to ensure safe and efficient switchgear operation.

Utility companies around the world are implementing fiber optic sensors for smart grid temperature monitoring of critical medium and high-voltage switchgear. These sensors provide real-time temperature data, enabling operators to maximize load efficiency and balance thermal stresses that can lead to catastrophic failures. Over time, switchgear contacts, bus bars, and critical connection points develop hot spots that slowly corrode causing increased electrical resistance. If left unchecked, even minor increases in resistance can quickly grow out of control as higher resistance creates hotter conductors, which, in turn, creates higher resistance. Transmission and Distribution (T&D) companies therefore routinely specify the requirement for continuous switchgear temperature monitoring to optimize maintenance schedules and extend equipment lifetime.

One of the challenges, however, has been to find a cost-effective technology for high-voltage sensing applications. Various RF (radio frequency) wireless and IR (infrared) thermometer sensors have been used, but each has its deficiencies. The RF transmitter/receiver sensors suffer from the inherent noise & interference that exists in a high-voltage environment and can lose signal or show temperature spikes during switching operations that may lead to false alarms. Also, because these sensors use electronic components, their temperature range is typically limited to below 120°C for long-term use. Remote IR temperature sensors fare similarly because they require shielded electrical wiring and special mounting points with precise spatial alignment to the object surface being sensed. Infrared thermometers are known to report temperature shifts due to dust accumulation and emissivity changes caused by subtle surface corrosion, especially on shiny metallic surfaces such as copper bus bars. The reported temperature can be skewed by reflected infrared energy emitted by surrounding objects, and sudden changes in ambient temperatures can also introduce measurement error.

OSENSA’s fiber optic temperature sensors do not suffer any of the technical challenges associated with wireless and infrared thermometers. Fiber optic sensors can be routed directly to critical switchgear monitoring points. OSENSA’s low-cost optical temperature sensors are rigidly attached to hot-spot locations and are completely immune to electromagnetic interference and noise bursts caused by high-voltage switching. OSENSA’s fiber optic sensors are robust, can be manufactured to various lengths, and work like a conventional thermocouple. Best of all, each OSENSA optical temperature sensor transmitter can monitor three phases providing both analog output and digital RS-485 Modbus RTU communication. OSENSA’s fiber optic temperature probes are perfectly suited for smart grid switchgear temperature monitoring.