What are the types of switchgear temperature measurement devices? Difference between online monitoring and handheld temperature measurement
Date: March 28, 2026 08:52:02
- Switchgear temperature measurement is a key means of preventing electrical fires and equipment failures, and contact overheating is one of the primary causes of switchgear accidents.
- Temperature measurement is mainly divided into handheld temperature measurement, wired online monitoring, wireless online monitoring of three categories, each applicable scenarios.
- Online monitoring is capable of collecting data 24 hours a day with automatic alarms, making it the preferred solution for unattended and critical sites.
- RFID wireless passive temperature measurement is currently the most popular new temperature measurement method, the sensor without batteries, maintenance-free, life expectancy of more than 10 years.
- Inotera provides a complete set of solutions for on-line monitoring of switchgear, including wireless passive temperature measurement and inductive temperature measurement.
I. Why does the switchgear need temperature measurement?
Switchgear is the core hub equipment of the power distribution system, with a large number of current-carrying components such as circuit breakers, bus bars, cable joints, knife gate contacts, etc. concentrated inside. These components in the long-term current-carrying process, due to increased contact resistance, contact pressure drop, oxidation and corrosion, etc., is very easy to produce abnormal heat in the local.
Contact overheating is one of the most common fault types in switchgear accidents. Initially, it is characterized by elevated contact resistance and slowly rising temperature. If it is not detected in time, the continuous accumulation of temperature will accelerate the aging of insulating materials, which may ultimately lead to insulation breakdown, short-circuit or even electrical fire, resulting in large-scale power outage and serious property loss.
What's more tricky is that the internal structure of the switchgear is closed, contacts, busbars and other hot parts can't be directly observed during normal operation, and the traditional manual inspection can't find any early temperature rise abnormality at all. This is exactly where the core value of the switchgear temperature measurement device lies - in places invisible to the naked eye, continuously guarding equipment safety.
Second, what are the common types of switchgear temperature measurement devices?
Switchgear temperature measurement solutions currently on the market can be divided into the following categories based on the measurement principle and usage:
| typology | Measuring principle | Whether or not a power outage is required for installation | Is monitored in real time | typical example |
|---|---|---|---|---|
| Handheld infrared thermometer | Non-contact infrared radiometric thermometry | unnecessary | ❌ Periodic manual measurements only | Handheld thermal imaging cameras, spot temperature guns |
| Fixed infrared temperature measurement | Fixed mounting of infrared sensors | Need a blackout. | ✅ Continuous monitoring | Fixed infrared probe + collector |
| Wired contact temperature measurement | Thermocouple/PT100 contact temperature measurement | Need a blackout. | ✅ Continuous monitoring | Wired Temperature Sensor + Acquisition Module |
| RFID wireless passive temperature measurement | Passive radio frequency sensing temperature measurement | Power outage required (for sensor installation) | ✅ Continuous monitoring | Inotera RFID passive wireless temperature measurement device |
| Induction pickup wireless temperature measurement | Current Sensing + Wireless Transmission | Need a blackout. | ✅ Continuous monitoring | Inotera Induction Temperature Monitoring System |
| fiber optic temperature measurement | Fiber optic sensing for temperature measurement | Need a blackout. | ✅ Continuous monitoring | Fluorescent Fiber Optic Temperature Measurement System |
In practical engineering.RFID wireless passive temperature measurementrespond in singingInduction pickup wireless temperature measurementBecause of its convenient installation and maintenance-free features, it is rapidly replacing the traditional wired program and becoming the mainstream choice for temperature measurement in low and medium voltage switchgear.
Third, what is the difference between online monitoring and handheld temperature measurement?
Handheld temperature measurement and online monitoring are currently the two most widely used temperature measurement modes, and many users are confused about how to choose at the beginning of the project. There is a fundamental difference between the two in the logic of use, coverage and operation and maintenance costs.
| comparison dimension | Handheld temperature measurement (thermal imaging camera) | Online monitoring (wireless/wired) |
|---|---|---|
| Monitoring continuity | Data only available during inspection hours, with significant blind time | 24-hour uninterrupted continuous acquisition without time blindness |
| Whether or not you need to open a cabinet | Safety risk due to need to open cabinet door or measure through viewing window | Sensors are fixedly mounted in the cabinet, no need to open the cabinet |
| Exception Response Speed | It will not be discovered until the next inspection, and may miss the rapid warming process | Temperature exceeds the limit immediately automatic alarm, timely response |
| Data logging and traceability | Reliance on manual recording, fragmented data, difficult to develop trend analysis | Automatic recording of historical data, traceable temperature trends |
| Degree of personnel dependency | Highly dependent on inspector experience and frequency | Automatic system operation, reducing manual intervention |
| Applicable places | Manned premises with good inspection conditions | Unattended stations, critical loads, dense distribution sites |
| Initial cost | Low equipment costs (thermal imaging cameras can be shared across multiple cabinets) | Higher initial installation costs |
| Long-term operation and maintenance costs | Continuous investment in manual inspection costs and high labor costs | Automatic system operation, low long-term operation and maintenance costs |
| remote access | unsupported | Support remote view data and alarm push |
Taken together, handheld thermometry is better suited as aAuxiliary means or transition programs for limited budget scenarios; online monitoring is a safer and more cost-effective long-term option for sites with high power supply reliability requirements, insufficient O&M staff or unattended sites.
Fourth, RFID wireless passive temperature measurement is what principle? What are the advantages?
RFID wireless passive temperature measurement is a new type of technology that has been rapidly popularized in the field of switchgear temperature measurement in recent years, and its core innovations areSensors are completely passive--No need for built-in batteries or external power supply lines, completely solving the problems of battery maintenance and wiring in the traditional temperature measurement program.
Working Principle
Passive temperature sensor adopts energy harvesting technology, through the collector antenna installed in the switchgear cabinet to transmit RF energy to the sensor, the sensor uses this part of the energy to complete the temperature measurement, and the temperature data will be transmitted back to the collector in a wireless way. The collector then uploads the data to the monitoring system or display instrument through the RS485 interface. The whole process does not require any power supply from the sensor itself.
Key Benefits
The sensor does not require batteries means that it is truly maintenance-free, with a service life of more than 10 years, without the hidden danger of failure due to battery aging. The small size of the sensor, tuning fork type, snap type, nut type packaging options, can be flexibly installed in the circuit breaker contacts, busbar lap joints, cable joints and other different forms of temperature measurement parts. Sensor protection level up to IP65, temperature range -40 ℃ to +250 ℃, can be adapted to the switchgear cabinet within the harsh environment of high temperature.
System Configuration
A single set of collector supports up to 12 temperature measurement points, and the standard configuration of 6 temperature measurement points is suitable for covering 6 key positions above and below the three-phase contacts on one side of the switchgear. The collector supports 35mm rail mounting, and the longest transmission distance of RS485 communication can reach 1000 meters, which has good system expandability.
V. What are the key parts of the switchgear temperature measurement?
The choice of temperature measurement points directly affects the monitoring effect. The following are the parts of the switchgear cabinet that are most prone to overheating and must be monitored:
Circuit Breaker Dynamic and Static Contacts
Contacts are the most concentrated part of the switchgear cabinet that generates heat. Frequent opening and closing operations over a long period of time will lead to contact surface wear, reduced contact pressure, and consequently increased contact resistance, making it a high incidence area for overheating faults. The tuning fork or snap-on passive sensors can be mounted directly on the contact fingers of the movable contacts to realize precise monitoring.
Female Connection Points
Loose bolts or oxidized contact surfaces at the busbar lap connection will significantly increase the contact resistance, especially under high-current conditions. The tuning fork sensor can be installed at the bolt position of the busbar connection to effectively capture the contact surface heat signal.
cable gland
The point where the incoming and outgoing cables are connected to the equipment is another high risk area for overheating, especially in older switchgear cabinets or distribution systems that have been retrofitted several times, where the quality of the cable joints varies and the risk of overheating is higher. Nut sensors are designed for such installation scenarios.
knife-gate contact
The contact surfaces of isolation knife gates also need to be monitored, especially when they have not been operated for a long period of time, the oxidation of the contacts is particularly prominent, and once they need to be operated they are prone to accidents caused by overheating.
VI. Which temperature measurement program should be chosen for different scenarios?
There are obvious differences in the requirements of temperature measurement programs for different use scenarios, the following selection recommendations for reference.
| application scenario | Recommended Programs | Recommended Reasons |
|---|---|---|
| Unattended substations | RFID wireless passive online monitoring | No manual inspection, automatic alarm, maintenance-free |
| Data Center Distribution Room | RFID wireless passive online monitoring | The power supply cannot be interrupted and needs to be constantly monitored in real time |
| Hospital, railroad distribution | RFID wireless passive online monitoring | Critical loads, requiring high fault response speeds |
| Plant electrical distribution room (with duty personnel) | Online monitoring, supplemented by handheld cameras | Online monitoring for continuity, thermal imaging cameras for in-depth inspections |
| Retrofit of old switchgear | RFID Wireless Passive Temperature Measurement (no need for major modifications) | No need to rewire, easy to install, suitable for stock remodeling |
| Small distribution rooms with limited budgets | Handheld thermal imaging camera + periodic inspections | Low initial cost for non-critical load locations |
| Ring main unit, cable joints key monitoring | Nutshell passive sensors for online monitoring | Exclusive packaging for cable glands for tight installation and accurate measurements |
Seven, the installation of switchgear temperature measurement device need to pay attention to what?
The quality of the installation of the temperature measurement device directly determines the accuracy of the monitoring data and the long-term reliability of the system, the following are a few key considerations.
Sensor installation must be operated without power
Regardless of the type of sensor selected, installation on circuit breaker contacts, busbars, or cable connector locations must be done under power failure. Snap-on sensors mounted on the moving contacts of the transfer switchgear need to be installed after swinging the trolley circuit breaker; sensors mounted on the incoming and outgoing busbar need to be operated only after confirming that the busbar is de-energized.
The sensor and the measured surface need to be in close contact with each other
The bottom of the sensor is the temperature sensing part, and must maintain good contact with the measured contact surface. If the contact surface is not flat, it is recommended to evenly apply thermally conductive silicone grease between the sensor and the measured surface to improve heat transfer efficiency and ensure accurate measurement.
Antenna arrangement to avoid strong power lines
RFID system collector transceiver antenna should be arranged in the sensor installation location near the switchgear cabinet wall, the antenna leads need to be introduced into the instrumentation room through the wire channel, the whole avoid touching and close to the strong power lines, to prevent electromagnetic interference affecting the signal quality.
RS485 communication line specification wiring
Communication cable should be shielded twisted pair, and power cables are laid separately to avoid parallel routing. When more than one collector is grouped into a network, it should be noted that the communication address setting should not be repeated, and the baud rate should be consistent to ensure that the data is uploaded normally.
Why choose Inotera switchgear temperature measurement solution?
Inotera is deeply engaged in the field of online monitoring of electric power equipment, providing a complete solution from sensor, collector to monitoring platform for switchgear temperature measurement, covering a wide range of equipment types, such as low and medium voltage switchgear, ring network cabinet, distribution cabinet, and so on.
RFID Wireless Passive Temperature Measurement - Truly Maintenance-Free!
Inotera RFID passive wireless temperature measurement system adopts innovative energy harvesting technology, the sensor does not need batteries, no power supply line, the service life of more than 10 years. Temperature measurement accuracy of ± 1 ℃, the temperature range covers -25 ℃ to +125 ℃, the sensor protection level IP65, temperature-resistant materials can withstand high temperatures of 250 ℃ without deformation. Stand-alone support for up to 12 temperature measurement points, RS485 interface communication distance up to 1000 meters, flexible access to various types of monitoring systems.
Multiple sensor packages for different mounting locations
Inotera provides three types of sensor packages: tuning fork, snap type and nut type, which correspond to different installation scenarios such as busbar bolts, circuit breaker movable contacts, cable joints, etc. One set of system can cover all the high-risk temperature measurement parts in the switchgear cabinet without the need for multiple sets of program superposition.
Complete switchgear online monitoring product line
In addition to temperature measurement devices, Inotera also provides a full range of switchgear partial discharge online monitoring, arc light online monitoring, circuit breaker operating characteristic monitoring, surge arrester online monitoring and so on.Switchgear monitoringThe product supports the integration of comprehensive monitoring system to meet the upgrade demand of users from single parameter monitoring to comprehensive state awareness.
If you are looking for a reliable temperature measurement or comprehensive online monitoring solution for your switchgear, please contact Innotranslate for professional selection advice and customized configuration.
statement denying or limiting responsibility
The content of this article is for general reference only, aims to introduce the basics of switchgear temperature measurement device and program comparison, does not constitute the only basis for any project implementation or procurement decisions. The technical parameters mentioned in this article are subject to the information on the official product page of InnoTech, and the actual specifications may vary due to the product model or customization requirements. Specific projects should be evaluated and confirmed by professional and technical personnel in conjunction with actual site conditions. The author and publisher of this article shall not be liable for any direct or indirect losses arising from reference to the contents of this article.
