Tag Archives: regeneration

The schedule of transformer oil maintenance oil type transformer maintenance

oil type transformer maintenance

The frequency of transformers maintenance depends on the importance, design features and durability of transformers. The first step towards a preventive maintenance program is testing. Testing helps us to determine when a treatment is necessary.

WHY DO WE NEED TO CHECK TRANSFORMER OIL?

Transformer oil is an insulator between the metal parts of the transformer and the wiring within the tank. Over time, the oil can be contaminated with moisture or create combustible gases. By sampling and testing that oil, we can plan repairing or replacing the transformer before a failure occurs.

Maintenance Schedule for Oil Filled Power Transformers

Maintenance or Test

Recommended Interval

 

Reference

Transformer physical inspection

 

Annually

Leakage of oil and reading of MOG (Magnetic Oil Gage) of tanks

Daily

In case of unsatisfactory oil level in the MOG, oil to be filled in transformer and also the transformer tank to be checked for oil leakage. If oil leakage is found take required action to plug the leakage. If silica gel becomes pinkish, it should be replaced.

 

Dielectric strength test (BDV) and moisture content (PPM).

 

Annually

A dielectric strength is a measure of the voltage which is conducted by the transformer oil. At times it is the presence of contaminants which conduct electricity faster than the oil which in turn lowers the dielectric breakdown voltage

Neutralization test

 

Annually

This test which is carried out to ascertain the level of acid which is present in the oil. When oxidation occurs in the transformer oil, it leads to build-up of acid.

Dissolved Gas Analysis Test (DGA)

Annually for 132 KV transformer, once in 2 years for the transformer below 132 KV transformer and in 2 years interval for the transformer above 132 KV transformer.

 

It helps to analyze the gases which are present in the transformer oil.

Bushings– check of oil level

 

Weekly

If it is required, the oil to be filled in the bushing up to correct level. Oil filling to be done under shutdown condition.

 

Bushings –visual inspection

 

Annually

Bushings – visual inspection and cleaning

 

5 years

Interfacial tension test

This is a test which is carried out to detect the presence of polar compounds such as paint, varnish and paper.

Tan & delta test

One in two years

Finally the presence of water too is measured as water can decrease the dielectric breakdown voltage of the transformer oil

Colour test

This test indicates aging, quality and the presence of contaminants in the transformer oil.

Transformer excitation current test

 

5 years

Insulating oil   – DGA, physical,

and chemical tests

 

Anually

Top oil and winding thermometer

Inspection

 

Anually

Oil level indicator operation

 

5 years

Sudden pressure relay

5 years

oil type transformer maintenance

oil type transformer maintenance

So, for getting high performance and long functional life of the transformer, it is desired to perform various maintenance activities. GlobeCores’s oil reclamation equipment will keep your transformer oil in the best condition, providing with oil degassing, water and solids removal as well as acids reducing. It’s a fantastic transformer life!

Reliability of Low Voltage Power Transformers

GlоbeCоre’s oil reclamation technology has been proven to cost effectively regenerate transformer oil thereby increasing the operational reliability of electric transmission equipment.

Before electric grid restructuring started, units with a voltage of between 110 and 500 kV (kilovolt) had constituted the greatest part of the fleet of transformers.  But the things have recently changed, today power companies routinely use transformers with voltage that is less than 110 kV with the majority of the transformers having a capacity of  less than 35 kV.

Table 1 analysis of the reasons for equipment damage depending on the point of fault.

Table 1

Damage Sources for Transformers with Voltage up to 35 kV

No.

Type of Fault

Rate of the total % of faults

1 Winding faults

19

2 Bushing insulator

3

3 Insulation faults

21

4 Insulation moistening

8

5 Oil

5

6 Voltage regulators

23

7 Contacts in windings

15

9 Other

6

As we can see, the greatest amount of damage is the result of insulation faults. That is why the condition of transformer oil is of such importance.  The efficiency of the entire insulation system (both solid and liquid) largely depends on the quality and condition of the dielectric transformer oil.  Such factors as temperature extremes, interaction with the atmospheric oxygen, and the accumulation of emulsion water have a negative impact not only on the performance characteristics of oil, but also on the condition of the solid insulation.  As a result, transformers break down prematurely even though their service life should be much longer.

Unfortunately, once the transformer has experienced a catastrophic failure,  there is only one solution to this problem.   The failed transformer willl have to be replaced by a new one.  But, such a strategy requires significant capital expenditures and leads to reduced profits and inefficient operations.

The solution to this problem is to call GlоbeCоre who is in the business of designing and producing equipment for purification and regeneration of transformer oils.

GlobeCore promotes and adheres to the principle of “preventive maintenance.”  That means that the causes of transformer damage are prevented in the first place during transformer servicing.  It is transformer oil purification that helps insulting oil maintain its performance characteristics at the proper level and slows down the process of its aging.

GlоbeCоre produces equipment that allows for complete processing of transformer oil (purification, dehydration, and degasifying) to restore the original performance characteristics of the dielectric oil.

GlоbeCоre equipment is also very eco-friendly: there are no harmful discharges into the air since it uses the sorbent that can be reactivated to prevent the penetration of oil residues into water and soil.  The service life of transformers with a voltage up to 35 kV may be extended by 10 years if negative impacts are reduced.

Directory of Intellectual Property – Regeneration of Sorbent Materials

Sorbent:   A solid substance with properties to absorb and retain water and other contaminants found in oils and hydraulic fluids.  It is used in modern equipment for industrial oil purification and regeneration.  These materials have high absorbent properties that are greatly valued when used in cleaning systems.  Another advantage of the sorbent is its ability to be recovered and be re-used.  Sorbent regeneration therefore, was a major factor that firmly cemented its place as part of modern high-tech oil purification equipment.

Methods for sorbent reactivation are classified as follows:  (1) Thermal (temperature <500°C/932°F), (2) heated (temperature 100°C/212°F-1400°C/2552°F), (3) chemical, (4) electrochemical granulation and (5) biological.  Heated, chemical and biological sorbent regeneration is performed without removing the sorbent from the sorbent blocks while thermal is performed without the use of adsorbers.

There are separate units that make automatic sorbent reactivation possible.  The most logical and cost effective thing to do is to use equipment that includes an automatic sorbent reactivation procedure as a part of the regeneration process for the used oils and hydraulic fluids.  Automatic, sorbent reactivation does not interrupt the regeneration operation and allows for a single independent closed cycle that is more efficient and cost effective.

GlobeCore’s wide range of models were created specifically to regenerate waste oil based on the the most advanced adsorption methods.  The GlobeCore CMM-R line of equipment is capable of returning used oils and hydraulic fluids back to their original new like condition.  Much to the joy of our clients, GlobeCore equipment that uses multiple units of sorbent cartridges can accomplish sorbent reactivation the following way:

The cleaning and purification process of waste oil depends on the connection between the oil-filled unit and the degassing, regeneration, and inhibitor blocks that make up the regeneration system of the CMM-R equipment line.  During the regeneration process, the oil is heated and filtered in a decontamination unit and is then fed to a regeneration block.  Regenerated oil is returned to the vacuum column in the degassing block, where under the influence of strong vacuum pressure and temperature, the gas is removed and the oil passes through the final filtration stage.

After the oil passes through the regeneration unit, the CMM-R unit then goes into the automatic sorbent reactivation mode.  Sorbent reactivation does not interrupt the oil regeneration process and the oil is purified in a degassing unit.  Automatic sorbent reactivation allows for high quality and cost efficient oil purification due to the constant reactivation of the sorbent materials.

The Regeneration Unit has several a containers that are half filled with sorbent material.  The lower part of the module consists of a rubber sleeve and bottom cover, through which the vacuum process, regenerated oil selection, and feeding of waste sorbent all take place.

Sorbent regeneration belongs in the category of modern patented technologies.  The exact formula of the sorbent cleaner process is a trade secret, but the whole process of regeneration utilizing sorbent reactivation can demonstrated and viewed at the GlobeCore facility upon request.