About Transformer Oil

Transformer oil is a fractionation product of petroleum. Its main components are alkanes and naphthenes. It is a light yellow transparent liquid. It is a kind of insulating oil. In oil-immersed transformers, transformer oil mainly plays the role of insulation and cooling.

Why is Transformer Oil Level Indicator so important?

The abnormal oil level of the transformer is mainly due to the oil level being too high and too low.

Oil level too high

When the transformer oil level is higher than the maximum oil level line. Depending on the cause, different methods should be used to deal with it.

If it is caused by overload, the load should be reduced.

If the three-phase current is seriously unbalanced and the current of a certain phase exceeds the rated value. The load should be adjusted to achieve a basic balance.

If the cooler is abnormal, the temperature of the transformer oil rises. Oil expands when heated. cause the oil level to rise. Then check whether the cooler is blocked by dust accumulation, and whether the upper and lower valves of the oil pipe are open. Whether the fan and submersible pump are running normally. Whether the temperature of the cooling medium is appropriate, etc. Prompt treatment returns the cooler to normal operation.

If the oil level is too high due to excessive oiling of the transformer, the oil should be drained to an appropriate height.

Oil level too low

When the transformer oil level is significantly lower than the oil level corresponding to the oil temperature at that time. The oil level is too low when the oil level is below the minimum oil level line or is not visible.

When the transformer leaks oil. The oil was not replenished in time after the oil was drained due to work, or the original oil level of the transformer was not high. When the transformer load suddenly drops or the external ambient temperature drops significantly, the oil level will be too low.

Too low oil level will cause gas protection action. When there is a severe shortage of oil, the transformer core and windings will be exposed to the air. It is easy to get wet and reduce the insulation ability, and may even cause insulation breakdown.

Therefore, when the transformer oil level is found to be too low. The reason should be found and dealt with.

If the oil level is low and no oil leaks are found. The operator should report and replenish qualified transformer oil of the same type as soon as possible.

If it is because of an oil leak, the oil level has dropped significantly. Measures should be taken to eliminate the oil spill and refuel immediately to bring the oil level back to normal.

If a lot of oil leaks. When the oil level drops too much, it endangers the safe operation of the transformer. A dispatch application should be reported to deactivate the transformer.

Transformers for large-scale strong oil circulating water cooling. If the oil level is found to be low. Check the water for oily flowers. To prevent water seepage in the oil from endangering the transformer insulation. Replenish the oil after finding out the cause.

On the other hand, the transformer oil level rises or falls due to seasonal changes. is a normal phenomenon.

If the oil level is too high in summer, try to drain the oil. When the oil level is too low in winter, try to refuel. In order to maintain the normal oil level and ensure the safe operation of the transformer.

Therefore, the normal oil level should be maintained when the transformer is running. In order to monitor the oil level of the transformer, the oil pillow of the transformer is equipped with a glass tube oil level gauge or a magnetic needle oil level gauge.

When the transformer is running, under normal circumstances, the oil level of the transformer changes with the change of the transformer oil temperature.

When checking the oil level, pay attention to whether it is a fake oil level.

When the oil pillow respirator is blocked, the vent of the explosion-proof pipe is blocked, the oil gauge pipe is blocked or the oil level gauge is damaged, the false oil level will appear.

At this time, although the changes of transformer oil temperature, ambient temperature, load, etc. are normal. But the oil level does not change or changes abnormally.

Extended reading: Ultrasonic Oil Level Sensor-External Paste-Truck Fuel Tank

Oil level indicator types for transformers

transformer oil level sight glass

An oil pillow is an oil storage device used in transformers.

Its function is that when the transformer increases the load, the oil temperature rises, and the oil in the oil tank expands, and then too much oil will flow into the oil pillow.

Conversely, when the temperature drops, the oil in the oil pillow will flow into the oil tank again. It can automatically adjust the oil level. That is, the oil pillow plays the role of oil storage and oil replenishment. Make sure the tank is full of oil.

At the same time due to the equipped oil pillow. Reduce the contact area between the transformer and the air. And the moisture, dust and oxidized grease absorbed from the air are deposited in the depositor at the bottom of the oil pillow. Thereby greatly slowing down the deterioration rate of transformer oil.

There is a glass oil level gauge (or oil level gauge) on the side of the oil pillow. The change of the oil level in the oil pillow can be observed at any time.

Pointer Type Oil Level Gauge

In power systems, oil-immersed transformers above 35 kV usually adopt a hermetic design. And equipped with oil conservator and oil level gauge with capsule bag.

The commonly used oil level gauges for transformers are divided into pointer oil level gauges and tube oil level gauges.

The working principle of the pointer oil level gauge is when the oil level of the oil conservator changes. Cause the change of the diaphragm, causing the linkage rod to move up and down. Through the action of magnetic torque, the driven magnet pointer is driven to indicate the oil level.

The working principle of the pointer oil level gauge is when the oil level of the oil conservator changes. Drive the oil float up and down, and use the pressure relief valve to adjust the oil level to indicate the oil level.

Extended reading: High Temperature Flow Meter

Monitoring Transformer Oil Conservator Oil Levels with Pressure Sensors

Pressure sensors are widely used in liquid height measurement. The liquid height can be obtained by measuring and converting the liquid pressure value. In the transformer conservator, an oil drain is usually connected to the bottom of the conservator for oil draining.

To eliminate the harsh requirements of mechanical transmission and fully enclosed conditions. At the same time, it can meet the precise measurement of the oil level of the oil conservator. By installing a pressure sensor at the end of the oil drain pipe. The oil level height of the oil conservator is calculated by the two-point pressure difference algorithm.

In liquid height measurement, it can be calculated by pressure, and the calculation formula of liquid pressure is:

P = ρgh

where:
ρ is the density of the liquid;
g is the acceleration of gravity, which is 9.8 m/s2;
h is the liquid level height.

Through the two pressure sensors installed in the oil level detection device, two pressure values P1 and P2 can be obtained,
in:
P1 = ρ1 gh1
P2 = ρ2 gh2
h3 = h1 – h2

For small objects in the transformer oil conservator, the oil temperature difference between the two points of the oil drain pipe is negligible, so it can be considered that ρ1 = ρ2, h1 can be obtained by calculation, and then the oil level can be calculated.

h1 = P1 h3 P1 – P2

where:
P1 and P2 are the pressure values of two points;
h3 is the height difference between two points (this value is a definite value).

By this method, the influence of the change of the insulation temperature of the oil conservator on the measurement results can be eliminated.

Extended Reading: Mechanical flow meter for diesel

Online Oil Level Monitor for Non-contact Transformer Conservator

The transformer oil pillows are all closed. The maintenance and replacement of the existing oil level gauges require power outages, openings, and oil draining, which is very complicated. Therefore, a non-contact transformer oil pillow oil level is installed in
Line monitor is very necessary.

Sonar ranging principle:

The probe is adsorbed on the bottom of the oil pillow by a magnet. The sonar wave (mechanical wave) emitted by the probe can penetrate the steel wall and propagate upward in the oil. It will be reflected back when it encounters the oil-gas interface, and detected by the probe.

The oil level height h.h=V×t/2 is calculated by detecting the time difference t between the transmitted wave and the returning wave combined with the sound velocity value V. of the oil.

The principle of sonar distance measurement is the best solution for non-contact measurement of oil level in the oil pillow.

It only needs to attach the probe to the outer wall of the bottom of the oil pillow through the magnet to measure the internal oil level height. The probe does not touch the internal medium. Real non-contact measurement is realized.

There is no need to open holes on the oil pillow, which is very convenient for installation and maintenance.

Extended reading: RF Admittance Level Sensor

Featured oil level indicator types

• Manual Oil Tank Level Measurement
• Magnetic flip level gauge for Tank Level Sensing
• Buoyancy Method for Oil Level Measurement
• Hydrostatic level gauge for Oil Level Measurement
• Ultrasonic method for Oil Level Measurement
• Electrical method for Oil Level Measurement
• Radar Level Sensors for Oil Level Measurement
• Magnetoelectric method for Tank Level Sensing

Related Blogs

Sino-Inst offers over 10 Solutions for Transformer Oil Level Indicator. About 50% of these are float liquid level meters, 40% are the level switches.

A wide variety of Solutions for Transformer Oil Level Indicator options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Solutions for Transformer Oil Level Indicator instrumentation, located in China.

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Featured External Tank Level Indicators for Sale

Difficulties Existing in Liquid Level Measurement in Industrial Storage Tank Industry

Most liquid fuels used in industry, such as liquefied petroleum gas, gasoline, diesel, lubricating oil and other refined oils, as well as liquid chemical gases. For example: liquid ammonia, liquid chlorine, are stored in a high-pressure airtight container. In the production process, in order to ensure the safety of production, it is necessary to regularly measure the liquid level of the remaining liquid in the closed container.

Because these liquids are flammable and explosive. Using the traditional liquid level measurement method will cause damage to the tightness of the container. Safety accidents such as liquid leakage are prone to occur. In particular, after the storage tank has been built and put into service. It is hoped that another principle that is different from the existing level gauge will be added, and a level gauge with a different principle will be used. It’s hard for businesses to choose.

Extended reading: What is a capacitive liquid level sensor?

No holes – No damage the tank – External Tank Level Indicator

In response to the above problems, we designed and produced a new type of non-intrusive ultrasonic liquid level measurement system – externally attached liquid level gauge. This enables a truly non-invasive, non-contact measurement method.

Simply mount the measuring probe on the outer wall of the tank or container bottom. The reflection and transmission properties of ultrasonic waves are utilized. Realize the measurement of the liquid level inside the storage tank. The calculated liquid level value is displayed locally and a remote signal is output.

The meter can output measurement results to the control system via 4-20 mA analog signal, HART, RS-485 and other interfaces. At the same time, the data can also be sent to the Internet through wireless transmission via WIFI, GPRS and NBIOT.

Extended reading: Diesel Tank Level Monitoring System

External Tank Level Indicator Applications

External Tank Level Indicator has a wide range of applications. Especially the liquid level measurement application of flammable, explosive, strong corrosive, toxic and harmful pressure vessel storage tanks is more prominent.

Medium:
Liquid chlorine, liquefied gas, liquid ammonia, hydrofluoric acid, propylene, vinyl chloride, ethylene oil, butane, chlorosilane, butadiene, C5, C4, ethylene oxide, butylene oil, silicon tetrachloride, refrigerant , liquid Australia, xylene, hydrochloric acid, nitric acid, lye, isopropanol, ethylene glycol, other media.

Industry :
Chlor-alkali, storage and transportation, petrochemical, refrigeration, coal chemical industry, oil refining, chlorination industry, fertilizer, pesticide, electric power, military, oil depot, liquid storage, and other industries.

Extended reading: level sensors for fuel tanks

Externally Attached Ultrasonic Oil Level Sensor – Trucks

Ultrasonic oil level sensor is an external sensor used to measure the liquid level height in tanks and containers.
The sensor uses the ultrasonic detection principle to measure the oil level（liquid level）, and then converts the measured height value into the oil volume value through intelligent processing, and then transmits the fuel volume data to the background supervision system through GPS to achieve the purpose of real-time monitoring of vehicle fuel consumption.

At present, the products are mainly used in the field of the Internet of Vehicles to monitor the changes in the internal oil level of the tank in real time, so as to realize the detection of fuel volume. It can be used to prevent oil theft, optimize operating costs, optimize driver driving behavior, assist statistical decision-making, etc. At the same time, this product can also be used in fields such as chemical industry, water conservancy, storage tanks and other fields with liquid level detection needs.

Extended reading: Ultrasonic Oil Level Sensor-External Paste-Truck Fuel Tank

Related Blogs

Read more about: Common River Water Level Measurement Methods

Sino-Inst offers over 10 External Tank Level Indicators and transmitters for level measurement. About 50% of these are ultrasonic liquid level meters, 40% is the level switches.

A wide variety of External Tank Level Indicators and transmitters options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of External Tank Level Indicators and transmitters instrumentation, located in China.

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Unique Technical Advantages of 80GHZ Radar Level Transmitter

80GHZ Radar Level Transmitter refers to frequency modulated continuous wave (FMCW) radar products operating at 76-81GHz. Four-wire and two-wire applications are supported. There are multiple models, the maximum range of the product can reach 120m, and the blind area can reach 8 cm.

Because the 80GHZ Radar Level Transmitter operates at a higher frequency. shorter wavelengths. So it is especially suitable for solid applications. The working method of transmitting and receiving electromagnetic waves through a lens. It has unique advantages in high dust and harsh temperature environment (+200℃).

80GHZ Radar Level Transmitter provides flange or threaded fixing, which makes installation convenient and easy.

The main advantages of 80GHZ Radar Level Transmitter are as follows:

• Based on self-developed CMOS millimeter-wave radio frequency chip. Enables a more compact RF architecture. Higher signal-to-noise ratio, smaller dead zone.
• The 5GHz operating bandwidth enables the product to have higher measurement resolution and measurement accuracy.
• The narrowest 3° antenna beam angle. Disturbances in the installation environment have less impact on the meter. Installation is more convenient.
• Shorter wavelengths and better reflection properties on solid surfaces. Therefore, there is no need for special use of universal flanges for aiming.
• Support remote debugging and remote upgrade. Reduce waiting time. Improve work efficiency.
• Support mobile phone Bluetooth debugging. It is convenient for on-site personnel to maintain work.

Extended reading: Non contact level measurement

Communication and debugging

The instrument can be debugged through the LCD in the field. It can also be debugged on the PC side with the optional host computer software.

The communication between the 80GHZ Radar Level Transmitter and the PC is as follows:

80GHZ Radar Level Transmitter Measurement Principle

The general principle of the FM continuous wave radar level gauge is that the radar emits electromagnetic waves on the top of the tank. And the electromagnetic waves are received by the radar after being reflected by the medium.

The frequency difference δf between the received signal and the transmitted signal is proportional to the distance R from the surface of the medium:

R=C (speed)*δf (frequency difference)/2/K (frequency modulation slope).

Because the speed of light C and the frequency modulation slope K are known.

The frequency difference δf can be estimated to obtain the distance R from the radar installation position to the material surface.

And then through the known total height of the tank. Subtract the spatial distance from the radar to the material surface (referred to as Empty height) to get the height of the material level.

Extended reading: Magnetostrictive Level Transmitter Working Principle

Terminology

Beam angle:
Beamwidth bounded by 3dB below the maximum value. The minimum beam angle of 80GHZ Radar Level Transmitter is 3°, as shown in the figure.

Distance Resolution:
Range resolution refers to the radar’s ability to distinguish between two objects that are very close together.

If the separation between the two objects is less than the range resolution of the level radar. Then the radar can only measure one distance value. This distance value is not equal to the distance value of any of the objects. It is a combination of the distance values ​​of the two objects.

The FM bandwidth of the 80GHZ Radar Level Transmitter is B=5.1GHz. Minimum distance resolution=C/2B≈3cm.

Measurement accuracy (Accuracy):
If there is only one object and this object has moved a small distance. Whether the level radar can detect distance changes. The indicator of how far a single object has moved is called accuracy.

The IF signal of the 80GHZ Radar Level Transmitter is analyzed by its own algorithm, and the measurement accuracy is 0.1mm.

Ambient temperature:
The temperature of the surrounding air in contact with the device enclosure.

Blind spot:
Refers to the measurement limit of the near end of the instrument, and the instrument cannot measure in the blind area.

dB (decibel):
Indicates the unit of signal amplitude.

Dielectric Constant (DK):
The ability of a dielectric to store electrical energy under the induction of an electromagnetic field. Often referred to as the relative permittivity.

The increase in the permittivity is directly proportional to the increase in the echo amplitude. The relative vacuum/dry air dielectric constant is 1.

Echo:
The reflected signal received by the radar.

Emission cone:
The extension of the antenna beam angle.

False echo:
Any echoes that are not generated by the desired target. Generally, false echoes are generated by obstructions in the container.

Multiple echoes:
The multiple reflection echoes appearing at the target echo distance may be 2 or 3 times.

Polarization:
Emitted electromagnetic wave properties, describing the direction and magnitude of the electric field vector that changes over time.

Range:
(1) Refers to the farthest measurement limit of the instrument
(2) Special, refers to the artificially set maximum distance. Outside this distance, the meter does not consider it when processing data.

Repeatability:
In the same test environment, measure the same reflective target multiple times to measure the deviation of the results.

Speed ​​of light:
Symbol C, the speed of electromagnetic waves. Includes electromagnetic waves and light in free space. The speed of light is 299,792,458 meters per second.

Threshold curve:
A time-varying curve that serves as a threshold beyond which echoes are considered valid.

Extended reading: Amazing Solutions for Continuous Liquid Level Measurement

Beam Angle

The beam angle is the beam angle when the radar wave energy density reaches half of its maximum value (3dB width). Microwaves emit signals outside the beam range and can be reflected by interference objects.

Lens antenna diameter	Φ32mmLens antenna	Φ42mmLens antenna	Φ78mmLens antenna
Beam angle	8°	6°	3°

The larger the antenna size, the smaller the beam Angle alpha, the less the interference echo will be generated.

For more accurate measurements, avoid installing any internal devices (such as limit switches, temperature sensors, bases, vacuum rings, heating coils, baffles, etc.) within the signal beam range.

Linear

Extended Reading: What is level transmitter working principle?

80GHZ Radar Level Transmitter Applications

80G high frequency radar level meter has the characteristics of high measurement accuracy, wide application range, non-contact measurement, etc. It can be widely used in material level and liquid level measurement of various highly corrosive and high dust media.

The 80GHz radar level meter can not only measure the liquid level, but also measure the solid material level. Including powder materials. It has a good application in different storage tanks. Process storage tanks (silo), reaction tanks, static storage tanks , Dome tank, flat-top tank, spherical tank, horizontal tank, stilling pipe, bypass pipe, tank with agitator.

Extended reading: Oil-water interface measurement-Magtech magnetic level indicator

Extended reading: Hydrostatic Level Measurement

More Featured Non-Contacting Radar Level Measurement

Read More about: List of Differences: Radar vs Ultrasonic Level Measurement

Related Blogs

Sino-Inst offers 80GHZ Radar Level Transmitters for level measurement.

A wide variety of 80GHZ Radar Level Transmitters options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of radar level measurement instrumentation, located in China.

Request a Quote

Material Level Monitoring

Level measuring instruments are industrial automation instruments that measure the liquid level and loading height of liquid and powdery materials. Measure the stacking height or surface position of solid materials such as lumps, granules and powders.

Material Level Monitoring is the measurement of the surface position of solid blocks or powders in a silo to understand the amount of material stored in the silo.

for example:
In thermal power plants, it is necessary to detect the position of coal lumps and pulverized coal in the raw coal hopper and pulverized coal bunker.

Featured Material Level Indicators

Cement Silo Level Measurement

Cement silo seems to be a simple supporting equipment for concrete mixing plant. In fact, it also contains many auxiliary devices. It is not just a simple silo. It also includes auxiliary devices such as dust collector, arch breaking device, pressure safety valve, Level meter, etc.

The material level meter is mainly used for automatic detection and control of the limit material level of various materials such as cement and fly ash. It is indispensable. What does it do?

The material level meter is a sensor used to sense the height change of the material in the container. It can continuously detect the height, volume and other values ​​of the material in real time and convey relevant information to the computer or display instrument.

In the concrete mixing plant, the cement silo is a closed material storage device. The user cannot intuitively understand the amount of powder in it. At this time, a material level meter is needed.

Simply put, the material level meter in the cement silo can accurately record the position of the material in the cement silo, which is convenient for management.

After understanding the function of the level meter, what are the characteristics of the level meter?

1. Anti-interference, ready to use:

Because there are no complicated electronic components and their amplifying circuit parts inside. Therefore, the level gauge is not subject to any electromagnetic wave interference. After installation, it can be used for a long time without any debugging and maintenance.

2. Super anti-shake performance design:

There are no false signals even when the material is flowing.

3. Shock resistance and anti-loosening structure design. Effectively avoid loosening and slipping of parts. High-quality stainless steel material is used to make it have excellent corrosion resistance and wear resistance.
4. The material level meter adopts contact measurement. The result is real, accurate and reliable. It can be installed horizontally, inclined and vertically. It is easy to install and use.
5. Material level display function:

Adopt long-life high-brightness indicator light. The material level display is intuitive and convenient.

6. Excellent measurement reproducibility and adaptability to environmental conditions:

That is, it is not affected by changes in material particle size, shape, specific gravity, medium, wall scale, adhesion, temperature, humidity, dust concentration, etc.

7. Double protection function:

The overload protection function prevents the blades from being damaged by excessive external force. The automatic protection function enables the material level device to be powered off when the rotation of the material blades is blocked in the silo, which protects the motor and effectively prolongs its service life.

Extended Reading: Silo/Bin material level measurement system

The Difference Between Material Level Indicator and Level Switch

First of all, the concept of Material Level Indicator and Level Switch is different.

Broadly speaking, Material Level Indicator is divided into two types: switch type and continuous type. It means that Material Level Indicator includes level switch.

In a narrow sense, the Material Level Indicator can detect the material level change in the container in real time, and can achieve continuous measurement. The material level switch only has the function of switching value, which can only monitor and control the point position, and cannot achieve continuous measurement.

Of course, in general, the instruments for continuous measurement use the naming method of Material Level Indicator. Most of the instruments for switching values use the naming method for level switches.

Secondly, the products covered by Level Switch and Material Level Indicator are different.

Divide from a narrow concept.

The material level switch mainly includes vibrating rod material level switch, resistance rotary material level switch, tuning fork material level switch, radio frequency admittance material level switch, etc.

Material Level Indicator mainly includes Ultrasonic Material Level Indicator, Radar Material Level Indicator, Ray Level Indicator, etc.

Related Blogs

Sino-Inst offers over 20 Material Level Indicators for level measurement. For detecting high, intermediate, or low levels of liquids, powders and free flowing granular solids stored in tanks, bins, silos or other containers. About 50% of these are Radar level meters, 40% is other tank level sensor.

A wide variety of Material Level Indicators options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Material Level Indicators instrumentation, located in China.

Request a Quote