BWY2-804 / BWY2-806 Transformer Oil Temperature Indicator, Controller and Thermometer Buying Guide-INNO

BWY2 is a transformer oil temperature indicator, controller and thermometer used for oil-immersed transformers.
It is also called an OTI gauge, oil temperature thermometer or transformer oil temperature controller.
The instrument is used for transformer oil temperature indication, cooling system control and over-temperature alarm.
BWY2 oil temperature instruments can provide adjustable switch contacts and Pt100 output according to model configuration.
4-20mA output and digital temperature display options are available for remote temperature indication and signal transmission.
Common model terms include BWY2-804A(TH), BWY2-804J(TH), BWY2-804AJ(TH), BWY2-804AA(TH), BWY2-804JJ(TH), BWY2-804BJ(TH) and BWY2-806AJ(TH).
For procurement, buyers should confirm model code, switch contact quantity, output type, capillary length, installation structure and digital display requirement.
For replacement projects, the old product label, wiring diagram and installation photo should be checked before ordering.

Selecting a BWY2 transformer oil temperature indicator, controller and thermometer is not only about choosing a similar-looking temperature gauge. In oil-immersed transformer applications, the OTI gauge is connected with oil temperature indication, cooling control, alarm output, remote signal transmission and panel display. A wrong selection may cause wiring mismatch, output signal mismatch, incorrect installation or unsuitable switch contact configuration.

This guide explains how to understand and purchase BWY2 oil temperature instruments from a buyer’s point of view. It covers the difference between indicator, controller and thermometer, OTI gauge working logic, model selection, output options, technical parameters, installation points, procurement checklist and FAQ. It is suitable for transformer manufacturers, substation users, EPC contractors, maintenance teams and buyers who need to replace or purchase transformer oil temperature gauges.

What Is a BWY2 Transformer Oil Temperature Indicator?

A BWY2 transformer oil temperature indicator is an OTI gauge used on oil-immersed transformers to indicate transformer oil temperature. It helps operators monitor transformer oil thermal condition and provides basic control signals for cooling and alarm circuits.

In practical transformer projects, the BWY2 instrument is more than a simple dial thermometer. It can work as a transformer oil temperature controller because it includes adjustable switch contacts. These contacts can be used to start cooling equipment or send over-temperature alarm signals according to the transformer control design.

For procurement, the important point is to understand that BWY2 is an oil temperature instrument. It is different from a winding temperature indicator. An oil temperature indicator focuses on transformer oil temperature, while a winding temperature indicator reflects simulated winding temperature.

Why Is BWY2 Called an Indicator, Controller and Thermometer?

Different buyers may use different names when searching for the same type of transformer oil temperature product. Some search for an oil temperature indicator, some search for an oil temperature controller, and some search for an oil thermometer. For BWY2, all three descriptions can be relevant depending on the function being emphasized.

Name Used by Buyers	Meaning	Typical Search Intent
Transformer Oil Temperature Indicator	Indicates transformer oil temperature	Looking for OTI gauge or replacement oil indicator
Transformer Oil Temperature Controller	Provides switch contacts for cooling and alarm circuits	Looking for control function and terminal output
Transformer Oil Thermometer	Pointer-type thermometer for transformer oil temperature	Looking for mechanical oil temperature gauge
OTI Gauge	Abbreviation of oil temperature indicator	Looking for transformer oil temperature product

How Does a BWY2 Oil Temperature Thermometer Work?

The BWY2 oil temperature thermometer is designed for transformer oil surface temperature detection and control. The temperature bulb is inserted into the transformer thermometer pocket filled with transformer oil. When the oil temperature changes, the instrument responds and indicates the oil temperature condition.

The BWY2 instrument also includes adjustable control switches. These switches allow the oil temperature controller to participate in transformer cooling control and over-temperature alarm circuits. For example, when oil temperature reaches a set point, the corresponding contact can be used by the transformer control system.

For buyers, this means the product should be selected according to both temperature indication needs and control output requirements. If the transformer only needs local indication, the configuration may be simpler. If the transformer control panel needs cooling control, alarm signal, remote display or analog output, the model and wiring configuration should be checked carefully.

When Should You Choose a BWY2 Transformer Oil Temperature Controller?

A BWY2 transformer oil temperature controller is suitable when an oil-immersed transformer requires oil temperature indication and temperature-related control output. It is commonly used on transformer bodies, control cabinets, substation panels and replacement projects.

Buyers usually choose BWY2 when they need a mechanical OTI gauge with switch contacts, signal output or optional digital display. It is also selected when an old oil temperature gauge needs replacement and the transformer still uses a traditional oil temperature indication structure.

Application Situation	Why BWY2 Is Used	Buyer Should Confirm
Oil-immersed transformer oil temperature indication	Provides local oil temperature reading	Temperature range, installation position and model code
Transformer cooling control	Provides adjustable switch contacts	Switch contact quantity and contact setting requirement
Over-temperature alarm	Supports alarm output according to temperature setting	Alarm circuit and terminal wiring
Remote temperature indication	Can be configured with signal output or digital display	Pt100, 4-20mA, display and communication requirement
Replacement of old OTI gauge	Can match traditional transformer oil temperature monitoring structure	Old model label, capillary length and installation photo

How to Read a BWY2 Oil Temperature Indicator Model Code

The BWY2 model code normally reflects the product series, scale form, control switch quantity, output function and special environment requirement. For procurement, the model code is very important because different suffixes may represent different signal output or application configurations.

When sending an inquiry, do not only write “BWY2 oil thermometer.” It is better to provide the full model code from the product label, such as BWY2-804A(TH), BWY2-804J(TH), BWY2-804AJ(TH) or BWY2-806AJ(TH), together with photos of the instrument and wiring terminals.

Code Item	Example Code	Meaning for Procurement
Product Series	BWY2	Transformer oil temperature indicator / controller series
Scale Code	80	Linear scale
Switch Contact Quantity	Configured by requirement	Used for cooling control and alarm circuits
Function Code	A	Pt100 output
Function Code	J	4-20mA output, two-wire type
Special Environment Code	TH / TA / T	Used for different tropical environment requirements

Common BWY2 Oil Temperature Indicator and Controller Models

Common BWY2 model names are often used in replacement projects and transformer product lists. The final configuration should still be confirmed by the full model label, output signal and wiring requirement.

Common Model	Product Type	Buyer Should Confirm
BWY2-804AJ(TH)	Transformer oil temperature indicator / OTI gauge	Output signal, switch contacts and wiring
BWY2-804AA(TH)	Transformer oil temperature controller	Pt100 configuration and contact setting
BWY2-804JJ(TH)	Oil temperature thermometer with output options	4-20mA configuration and terminal wiring
BWY2-804A(TH)	Transformer OTI gauge with Pt100 output	Remote display or monitoring requirement
BWY2-804J(TH)	Oil temperature controller with 4-20mA option	Analog output and panel connection
BWY2-804BJ(TH)	Transformer oil temperature instrument	Complete model suffix and output type
BWY2-806AJ(TH)	Transformer oil temperature indicator and controller	Switch contact configuration and site installation

Technical Parameters for BWY2 Oil Temperature Indicator, Controller and Thermometer

The following technical table is useful for buyers comparing transformer oil temperature indicators. Final values should be confirmed according to the actual ordered model, project requirement and product drawing.

Product Name	Transformer Oil Temperature Indicator / Controller / Thermometer
Product Series	BWY2 Series
Application	Oil-immersed transformer oil temperature indication and control
Operating Ambient Temperature	-40°C to +80°C
Relative Humidity	≤95% at 25°C
Measuring Range	-20°C to 140°C
Accuracy	Class 1.5; maximum allowable error at detection point ±2.4°C
Switch Contacts	2-4 adjustable switch contacts
Switch Rated Power	AC220V / 5A
Temperature Bulb Size	Φ14 × 150 mm
Mounting Thread	M27 × 2 mm
Capillary Length	According to the last group of digits in the instrument number
Protection Grade	IP55

Output Options for BWY2 Transformer Oil Temperature Controller

For transformer monitoring panels, buyers often require more than local pointer indication. The BWY2 oil temperature controller can be selected with different output options according to the monitoring and control system.

Output / Control Option	Purpose	Selection Note
Switch Contacts	Cooling control and over-temperature alarm	Confirm contact quantity and control circuit function
Pt100 Output	Remote resistance temperature signal output	Confirm receiving device compatibility
4-20mA Output	Analog signal transmission	Confirm whether current output is required
Digital Temperature Display	Remote display and signal control	Confirm input signal and power supply
RS485 Communication	Connection with monitoring or control systems	Confirm communication requirement before ordering

Digital Temperature Display Options for BWY2 Oil Temperature Thermometer

The optional digital temperature display can be used together with the BWY2 oil temperature thermometer for remote temperature indication, signal transmission and control output. This is useful when the transformer temperature signal needs to be displayed in a control panel or transmitted to a monitoring system.

Accessory	Digital Temperature Display
Operating Ambient Temperature	-10°C to +50°C
Relative Humidity	≤85%
Power Supply	AC/DC100–265V, 50–60Hz
Output Signal	4-20mA analog current, RS485 communication
Display Type	Digital tube display
Accuracy	Class 1.0
Panel Opening Size	153 × 77 mm
Overall Dimensions	160 × 80 × 120 mm

How to Select the Right BWY2 Transformer Oil Temperature Thermometer

For a new transformer project, selection should start from the transformer temperature monitoring design. For a replacement project, selection should start from the existing model code and wiring information. In both cases, the complete configuration should be confirmed before ordering.

Step 1: Confirm the Temperature Type

First confirm that the required instrument is for oil temperature indication, not winding temperature indication. If the project needs transformer oil temperature display, cooling control and oil temperature alarm, BWY2 OTI gauge is the correct product category.

Step 2: Confirm the Full Model Code

The full model code helps identify output type, contact configuration and environmental code. For replacement projects, take a clear photo of the old product nameplate before sending an inquiry.

Step 3: Confirm Switch Contact Requirement

The number and function of switch contacts should match the transformer cooling and alarm circuit design. Contact function should be confirmed before production or replacement.

Step 4: Confirm Output and Remote Display Requirement

Check whether the project needs Pt100 output, 4-20mA output, digital temperature display or RS485 communication. Different output requirements may change the model suffix and wiring configuration.

Step 5: Confirm Installation Conditions

Before ordering, confirm the thermometer pocket, mounting thread, capillary tube length, wiring position and control panel layout. This helps avoid installation mismatch after delivery.

Procurement Checklist for BWY2 Oil Temperature Indicator, Controller and Thermometer

Use the following checklist before sending an inquiry for a BWY2 transformer oil temperature indicator, controller or thermometer.

Information to Confirm	Why It Matters
Transformer type	Confirms whether the product is suitable for oil-immersed transformer use
Existing model code	Helps match replacement configuration
Switch contact quantity	Affects cooling and alarm circuit wiring
Output signal	Determines Pt100, 4-20mA or digital display requirement
Temperature bulb and mounting thread	Affects thermometer pocket compatibility
Capillary length	Affects field installation and routing
Installation photo	Helps confirm mounting and replacement details
Wiring diagram	Avoids terminal and output mismatch

Installation Notes for BWY2 Transformer Oil Thermometer

The BWY2 transformer oil thermometer should be installed vertically. Before inserting the temperature bulb, the transformer thermometer pocket should be filled with transformer oil. The temperature bulb should be inserted slowly and fixed properly to ensure correct oil temperature sensing.

The capillary tube should be protected during installation. It should not be excessively bent, stretched or compressed. For replacement projects, the existing capillary routing and installation space should be checked before ordering.

For panel-mounted digital display options, the display should match the reserved opening in the control cabinet. Buyers should confirm the panel opening size, power supply, input signal and communication requirement before selecting the digital display configuration.

Common Mistakes When Buying BWY2 Oil Temperature Controllers

Mistake 1: Treating OTI and WTI as the Same Product

OTI and WTI are different transformer temperature instruments. BWY2 is used for oil temperature indication, while winding temperature indicators are used for winding temperature indication. Buyers should not replace one with the other without checking the transformer design.

Mistake 2: Ordering Only by Product Picture

Many transformer thermometers look similar from the front. However, internal configuration, contacts, outputs, capillary length and wiring may be different. Always check the model code and terminals.

Mistake 3: Not Confirming Output Signal

Some projects require only local indication, while others require Pt100, 4-20mA, digital display or RS485 communication. Confirm the output requirement before ordering.

Mistake 4: Ignoring Installation Structure

For replacement projects, installation details are critical. Confirm the thermometer pocket, mounting thread, capillary routing and control cabinet layout before final selection.

Mistake 5: Ignoring the Switch Contact Function

Switch contacts may be used for different cooling or alarm circuits. The buyer should confirm how many contacts are required and what each contact controls.

BWY2 Oil Temperature Indicator vs BWR2 Winding Temperature Indicator

Buyers sometimes confuse oil temperature indicators with winding temperature indicators because both are used on oil-immersed transformers. However, their monitoring purpose is different.

Item	BWY2 Oil Temperature Indicator	BWR2 Winding Temperature Indicator
Temperature Type	Transformer oil temperature	Simulated transformer winding temperature
Common Name	OTI gauge / oil thermometer	WTI gauge / winding thermometer
Control Purpose	Cooling control and over-temperature alarm	Cooling control, alarm and trip protection
Selection Focus	Temperature bulb, oil pocket, output type and contact output	Composite transmitter, CT signal and contact output

FAQ About BWY2 Transformer Oil Temperature Indicator, Controller and Thermometer

What is the BWY2 transformer oil temperature indicator used for?

It is used for oil-immersed transformer oil temperature indication, cooling system control and over-temperature alarm.

Is BWY2 an oil temperature controller or thermometer?

It can be described as both. It indicates oil temperature like a thermometer and provides control contacts like a temperature controller.

What is the difference between BWY2 and BWR2?

BWY2 is used for transformer oil temperature indication, while BWR2 is used for transformer winding temperature indication.

Can BWY2 provide remote output?

Yes. Depending on the selected model, BWY2 can support Pt100 output, 4-20mA output or matched digital temperature display options.

Can BWY2 be used for transformer cooling control?

Yes. BWY2 oil temperature controller can provide adjustable switch contacts for transformer cooling control according to the project design.

What information should I provide before buying BWY2?

Provide the old model code, transformer type, switch contact requirement, output signal, capillary length, installation photo and wiring diagram.

Can BWY2 replace a winding temperature indicator?

No. BWY2 is for oil temperature indication. Winding temperature indication should use a WTI gauge or winding temperature indicator.

Is a digital display available for BWY2?

Yes. A digital temperature display can be selected for remote temperature indication, signal transmission and signal control.

Conclusion: How to Buy the Right BWY2 Transformer Oil Temperature Indicator, Controller and Thermometer

The BWY2 transformer oil temperature indicator, controller and thermometer is used for transformer oil temperature indication and control. It is suitable for oil-immersed transformers that require OTI indication, cooling control, over-temperature alarm and remote signal options.

For correct procurement, buyers should not select only by product appearance. The full model code, output type, switch contact quantity, capillary length, thermometer pocket, wiring diagram and digital display requirement should all be confirmed before ordering.

FJINNO can help select BWY2-804A(TH), BWY2-804J(TH), BWY2-804AJ(TH), BWY2-804AA(TH), BWY2-804JJ(TH), BWY2-804BJ(TH), BWY2-806AJ(TH) and related transformer oil temperature indicator models according to project requirements or replacement information.