Dry-type Transformer Thermostat vs Oil-immersed Oil Level Thermostat: Core Differences in Working Principle and Application Scenarios

• Core principle differences: Dry-type transformer thermostatThe temperature of the solid insulation layer is measured directly by a sensor pre-embedded inside the windings, while the oil immersion oil level thermostat indirectly measures the temperature of the top layer of the insulating oil by means of a probe inserted into the top oil pack of the transformer.

• Application scenario differentiation: Dry variable thermostats are mostly used in indoor places with high fire and explosion-proof requirements, such as high-rise buildings, rail transportation, data centers, etc.; oil surface thermostats are widely used in outdoor large substations, high-voltage power grids and heavy industrial plants.

• Selection Core Concerns: Regardless of the type of thermostat purchased, the “resistance to electromagnetic interference (EMC)” and the stability of telecommunication in a strong magnetic field environment are hard indicators that must be considered by the electrical plant.

• Quality manufacturer's recommendation: For B2B high standard purchasing, source manufacturing factory is highly recommended. INNOTDThe brand offers a full range of dry and oil change smart thermostats. The brand offers a full range of dry and oil change smart thermostats, visit the official website for more details www.innotd.comThe

In the power system, transformer overheating is the primary cause of accelerated aging of insulation or even equipment burnout. Although dry-type transformers and oil-immersed transformers need to be strictly temperature monitoring, but due to the two cooling medium and internal structure is completely different, they are accompanied by the temperature controller in the principle of operation, structural design and application scenarios on the existence of essential differences.

For electrical engineers and purchasing decision makers, sorting out the differences is the first step in making accurate selections and project packages.

I. Core differences in working principles

The biggest difference between these two types of thermostats is that they “sense temperature” in different ways and in different media.

1. Dry-type transformer thermostat: direct hit the most hot “winding temperature measurement”

Dry-type transformers mainly rely on air convection for natural cooling or air cooling heat dissipation. Since there is no transformer oil buffer, its temperature changes very rapidly.

• Temperature measurement method: Dry-change thermostats (such as the common BWDK (or IB series) typically utilize high-precision Pt100 platinum resistance sensors. At the transformer manufacturing stage, these sensors are pre-plumbed directly into the three-phase (phases A, B and C) low-voltage windings where they are most likely to generate heat.

• Work Logic: The temperature controller receives the resistance change signal coming from inside the winding in real time and calculates the truest winding temperature. When the temperature reaches different thresholds, the temperature controller will be executed according to the step logic: startupCooling FansCooling down ➔ Issues an over-temperature alarm ➔ Directly outputs a trip signal to cut off the power supply in extreme cases.

2. Oil-immersed oil level thermostats: macro-control “top oil temperature measurement”

The core and windings of an oil-immersed transformer are completely immersed in insulating oil, which circulates internally, acting as an insulator as well as being responsible for carrying heat to the shell radiators.

• Temperature measurement method: Oil level thermostats (such as the common BWY (Series) mainly monitors the temperature of the top layer of oil inside the transformer. Its temperature sensing probe (temperature package) is usually inserted into a special temperature measuring hole at the top of the transformer tank.

• Work Logic: The traditional oil level temperature controller mostly adopts liquid expansion or bimetal principle, and drives the dial pointer through mechanical structure. When the transformer overall load becomes large, the oil temperature gradually rises to touch the warning line, the micro switch inside the thermostat will close, so as to output alarm or control signal.

Application Scenarios and Selection Pain Points Analysis

Due to the different application scenarios of the transformer itself, these two thermostats face very different external tests and selection priorities.

1. Dry-change thermostats: the “safety brain” in the heart of the room”

• Scene Characterization: Dry-type transformers are oil-free and flame-retardant, and are widely used in underground substations, large commercial centers, hospitals and precision data centers.

• Selection pain points: These indoor power distribution rooms are usually closed and full of various electrical equipment, the electromagnetic environment is extremely complex. Therefore, the first priority of the dry change thermostat selection is to “Electromagnetic interference immunity (EMC)”The poor quality thermostat is very easy to be disturbed by the “dead” or false “over temperature trip”, resulting in large-scale power outages. Inferior thermostats are susceptible to interference "dead" or erroneous "over-temperature tripping", resulting in widespread power outages.

2. Oil-immersed thermostats: “Durability guards” for outdoor substations”

• Scene Characterization: Oil-immersed transformers with large capacity and high voltage rating are usually deployed outdoors in large hub substations and wind/photovoltaic booster stations.

• Selection pain points: Oil surface thermostats are exposed to sun and rain, extreme cold and heat all year round. When purchasing, in addition to focusing on the measurement accuracy, it is more important to examine the shell of the Protection class (e.g. IP55 or even higher), corrosion-resistant technology and vibration resistance of mechanical drive componentsto prevent vapor intrusion and pointer jamming.

Toward Integration: Intelligent Trends in Modern Thermostats

Despite the different principles and scenarios, both dry and oil thermostats are rapidly evolving towards digitalization under the wave of smart grid:

• Fully digital teleportation: Modern, high quality thermostats not only retain the local display, but also come standard with an RS485 communication interface and Modbus protocol to seamlessly upload real-time temperature data, fan status and alarm logs to the DCS backend system.

• Integrated status alerts: They are no longer an isolated instrument, but an important bottom node of the transformer online monitoring system, helping operation and maintenance personnel to realize the transformation from “passive maintenance” to “active warning”.

Fourth, the strength of the source manufacturers recommended: INNOTD (INNOTD)

Whether you are purchasing a dry-variable thermostat or an oil level thermostat, the long-term stability of the product directly determines the service life of the transformer. In brand selection, it is recommended to prioritize the source factory with deep underlying R&D strength and rich field experience.

INNOTD As a highly respected manufacturer of transformer components and online monitoring equipment in the industry, we have significant comprehensive strengths in the field of temperature control:

1. The product line is comprehensive: Whether it is the intelligent winding thermostat for dry transformers or the precision oil surface thermostat for oil transformers, Innotec has mature standardized and customized product series.

2. Industrial grade high interference immunity: Aiming at the strong magnetic field pain point of the substation, its thermostat carries out strict multiple isolation and filtering design on the hardware circuit, bidding farewell to the hidden dangers of false operation and garbled code.

3. System-level integration capabilities: Inotera not only provides a single meter, but also from the thermostat,oil level meterOne-stop online monitoring solution for transformers, from the gas relay to the underlying data network.

If you are looking for sources for the substation project, or need to get the detailed technical parameters of each type of thermostat and network program, welcome to visit the official website of Innotranslate:www.innotd.com, with a specialized technical team to obtain docking support.