Troubleshooting of distribution transformer

Troubleshooting of distribution transformer

Transformers plays a very important role in the power system. Though they are some of the most reliable component of the electrical grid they are also prone to failure due to many factors both internal or external. There could be many initiators which cause a transformer failure, but those which can potentially lead to catastrophic failure are the following :.

In both cases, the transformer is no longer able to perform its intended function of carrying load and stepping down or up the voltage. The main point of concern in ageing and the life expectancy of transformers is the condition of the insulation system, which is typically based on organic products.

The organic products in a transformer degrade over time and finally they lose the capability to withstand the stresses a transformer might see in daily life. The following graph describes the relative failure rate of a whole group of similar products like transformers. Some modes of failure can occur regardless of construction type.

These might include tap changer failures, bushing failures, tank failures, moisture ingress, and other forms of dielectric fluid contamination. And sometimes it could be due to natural causes like lightning which causes electrical surge in the power lines. In more interesting fashion it sometime also happens due to snakes, squirrels etc. Mechanical failures can be the result of shipping damage, seismic activity, and thru-faults.

The obvious result of a mechanical failure is the displacement of winding turns or damage of the turns by the forces exerted during the damaging event.

Moreover change in low voltage excitation current, a change in impedance, and sometimes, the presence of partial discharge PD during an induce voltage test can also give valuable indications about a mechanical failure in the transformer.

Mechanical failure is often discovered by electrical failures which are the result of mechanical deformation. Electrical failures are the result of insulation degradation. This can be caused by thermal degradation over the life of the transformer, by thermal degradation due to excessive or frequent fault current, or by dielectric breakdown due to high voltage stress. A dielectric breakdown can also be the result of mechanical forces tearing the insulation. The result of a electrical failure can be a turn to turn failure.

The consequences can be arc from the energized winding to an adjacent winding or to ground. It is important to note that overloads rarely result in transformer failures, but do cause thermal aging of winding insulation. Because of this exponential relationship, transformer overloads can result in rapid transformer aging.

Troubleshooting of distribution transformer

When thermal aging has caused insulation to become sufficiently brittle, the next fault current that passes through the transformer will mechanically shake the windings, a crack will form in the insulation, and an internal transformer fault will result. Shell form construction is resistant to winding deformation due to thru-faults.

The exposure to conductor bending is limited by many support spacers to avoid beam bending. Form fit tank and core prevent movement of the core and winding groups.

troubleshooting of distribution transformer

Failure can be prevented by adequate support of the outer turns. Core form construction can exhibit failure in several ways. Radial tension failure, also known as hoop tension failure, can occur;conversely, radial compression failure can also occur. Radial failure can collapse the inner winding unless the winding support structure is strong. Axial failures can occur in both compression and tension.Failure of transformer in power substation is not a sudden phenomenonfor that matter each and every failure will take place only after alerting through some pre-signs.

If they went unnoticed or unattended will results into a failure. Therefore it is wise on the part of the maintenance personnel to act upon the pre failure signs noticed well in advance to keep the transformer failure free and serviceable at all times. If new transformer is installed for which there is no past experience, it will be difficult to forecast the defects and probable failures. In most cases the causes of the fault can be surmised by careful observation of the condition of windingse.

This is characterized by break down of the end turns close to the line terminal.

How to Troubleshoot a Low-Voltage Transformer

There may be a break in the turns or end lead, and also flash marks on the end coil and earthed parts close to it, but the rest of the coils will be found to be healthy. The windings in one or all phases would show signs of overheating and charring. The insulation would be very brittle and would have lost all its elasticity.

troubleshooting of distribution transformer

The same signs as for indicated for sustained overload would be noticed, but only on affected coils, the rest of the coils being intact. This can be identified by the unmistakable, lateral or axial displacement of the coils. The coils may be loose on the core, some turns on the outermost layer may have burst outwards and broken as if under tension. If, in addition to these signs, the windings are also completely charred, it is conclusive evidence that the short circuit has continued for an appreciable period, not having been cleared quickly by the protective relays.

If the upper chamber of the Buchholz relay alone has tripped, check the insulation of core bolts, by applying a voltage of V to V between the core and each bolt.

If it fails, renew the insulating bush. If the oil shows a low break down voltage BDVit does not necessarily mean it has caused the breakdown. At high voltage ratings, excessive moisture content in the oil may result an internal flashover between the live parts and earth, which all leave corresponding tell tale marks.

Search for:. Premium Membership. More Information. Transformer Failure Failure of transformer in power substation is not a sudden phenomenonfor that matter each and every failure will take place only after alerting through some pre-signs.

Further if a failure occurred even though all the known precautions were observed, then it is necessary and more advantageous to investigate into the failure in such a manner to pull out the actual reasons of failure so that action shall be initiated to avoid recurrence.During these challenging times, we guarantee we will work tirelessly to support you.

We will continue to give you accurate and timely information throughout the crisis, and we will deliver on our mission — to help everyone in the world learn how to do anything — no matter what. Thank you to our community and to all of our readers who are working to aid others in this time of crisis, and to all of those who are making personal sacrifices for the good of their communities.

We will get through this together. Updated: March 29, Reader-Approved References. Transformers are an electrical component that transmit electrical energy between at least two circuits. Transformers regulate the voltage in circuits, but in some cases these can go bad and cause a circuit to not work. You'll need to identify key information about your transformer, like whether it's suffered visible damage and what its inputs and outputs are. After that, it should be relatively simple to test the transformer with a digital multimeter DMM.

Should you continue having problems with the transformer, you'll need to troubleshoot it. To test a transformer with a digital multimeter DMMfirst turn off power to the circuit.

Next, attach the leads of your DMM to the input lines. Otherwise, use the DC scale to determine what the issue is. To learn how to troubleshoot your transformer, keep reading! Did this summary help you? Yes No.

troubleshooting of distribution transformer

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Article Edit. Learn why people trust wikiHow. This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness.

Together, they cited information from 11 references. Learn more Testing a Transformer with a DMM. Troubleshooting Your Transformer. Tips and Warnings. Things You'll Need. Related Articles. Article Summary.

Part 1 of Inspect the transformer visually. Overheating, which causes the internal wiring of the transformer to run at elevated temperatures, is a common cause of transformer failure.This course describes methods that can be used to troubleshoot two types of problems that may affect URD systems: transformer faults and cable faults.

Toggle navigation. Breadcrumb Home Courses Underground. Course ID. Describe methods that can be used to troubleshoot transformer faults. Describe methods that can be used to troubleshoot cable faults.

How to Troubleshoot Electrical Transformers

Identify equipment used in the troubleshooting process. Describe how to troubleshoot a transformer fault in which only the transformer primary fuse is blown. Describe how to troubleshoot a transformer fault in which the rise pole fuse is blown, but the transformer primary fuse is intact.

Isolating Cable Faults — Part 1 Describe how to troubleshoot a cable fault in a system equipped with cable fault indicators. Identify three common types of cable fault indicators. Describe how to troubleshoot a cable fault by isolating and testing one section of cable at a time starting at the normally open point in the loop.

Describe how to troubleshoot a cable fault by isolating and testing one section of cable at a time starting at a blown riser pole fuse.

Isolating Cable Faults — Part 2 Describe how to troubleshoot a cable fault by re-energizing one section of cable at a time. Describe how the area to be isolated and tested for a cable fault in a URD system can be reduced. Describe the major difference between troubleshooting a transformer fault or a cable fault in a three-phase system and troubleshooting a transformer fault or a cable fault in a single-phase system. Describe how to troubleshoot a cable fault using a radar fault locator.

Specialty Package. Electrical Cable Installer Training. Troubleman Training. Search Search.Violin string replacement near me Automatic email reply machine learning. Erase detox total eclipse Li ziqi cooking. How to update eu4 mods. Fundamentals of Power Electronics Chapter Transformer design13 2. Evaluate peak ac flux density At this point, one should check whether the saturation flux density is exceeded. Gibson accessories.

What are the requirement of utilities and overheads for Low-voltage transformers do not wear out.

troubleshooting of distribution transformer

A technician should troubleshoot the transformer and find the reason it failed before replacing it. Usually, a transformer fails only after another part in the electrical circuit shorts to ground or draws an unusually high amperage.

Oil-Filled Transformer Inspections continued 4. Transformers either increases or decreases AC voltage. Transformers are used to meet a wide variety of needs.

Some transformers can be several stories high, like the type found at a generating station or small enough to hold in your hand, which might be used with the charging cradle for a video camera.

All transformers produce sound due to the vibration generated in its core by alternating flux. Determine the value of the coefficient of coupling k for the transformer of Example 4. For the ideal transformer circuit of Fig. If anda determine the turns ratio a, b the source voltageand c the input power factor. Therefore if the unit is defective or is damaged, the entire three-phase transformer has to be shut down.

Cost of repair: The cost to repair a 3-phase transformer is higher since changing each individual component is expensive. Hence, to restore the service, the spare unit Power Substation Services is the nation's leader in the installation and servicing of substation transformers.

Our expert crews travel across the country to provide oil and electrical testing services, as well as transformer maintenance and repair. Maximum contribution of distribution transformer is restricted by rated capacity of each phase.

When distribution transformer operates under the condition of three-phase load imbalance, one-phase with small load will have bigger capacity than needed, thus reducing contribution of distribution transformer. The fast, durable repair of oil and gas leaks with PowerPatch is an economical and effective means to protect essential electrical grid assets.

Rcs 3d design. Project manager Strategic commercial departmentBuchholz relay for transformer protection is only applicable for oil immersed transformer- used mostly for transformers with ratings above KVA, it provides protection from all kinds of faults.

It is positioned between transformer oil reservoir and transformer oil tank - in the piping system where the piping is inclined by 9.Use this link to find the product you need.

Skip to content Hot transformer. Possible Cause Suggested Remedy High ambient temperature Improve ventilation or relocate unit to cooler location.

Overload Reduce load; reduce amperes by improving power factor with capacitors; check for circulating currents for paralleled transformers — different ratios or impedances; check for open phase in delta bank.

High voltage Change circuit voltage, taps. Insufficient cooling If other than naturally cooled, check fans, pumps, valves and other units in cooling systems. Short-circuited core Test for exciting current and no-load loss; if high, inspect core, remove and repair; check core bolt, clamps and tighten; check insulation between laminations; if welded together, return to factory for repair or replacement.

High harmonic loads Measure neutral current — replace with K-rated transformer. Noisy transformer. Metal part ungrounded, loose connection Determine part and reason; check clamps, cores and parts normally grounded for loose or broken connections, missing bolts or nuts, etc.

External parts and accessories in resonant vibration Tighten items as above; in some cases, loosen to relieve pressure causing resonance and install shims. No or unsteady voltage.

Possible Cause Suggested Remedy Winding failure — lightning; overload; short-circuit from foreign object or low strength dielectric Check winding; remove foreign object or damaged material; repair or replace parts of insulation materials. Rust and paint deterioration. Possible Cause Suggested Remedy Weather, pollution, corrosive or salt atmosphere; overloads Remove rust and deteriorated paint; clean surfaces; repaint with proper paints and sufficient coatings.

Excessive heating discoloration If excessive heating discoloration occurs, check sizing, input voltage, or loading amps. Hot neutral line. Severe unbalance between phase: rebalance and equalize loads. One leg of wye bank open Check associated fuse. If blown, remove cause and replace.Thanks for sharing good information.

Hi boss You are mentioned Action shall be same as internal fault procedures what is that. Stop of transformer. Except OLTC. Internal fault of. Operation of differntial relay and buchholz relay or pressure relief device operate simultaneously. Action shall be same as internal. Operation of buchholz relay and pressure relief device. Operation of. Operation of buchholz relay trip only. Operation of pressure device Only.

Winding temp. Operation of relays such as overcurrent relay, ground relay, arrestor etc. In the system. Heavy current. Abnormality is found in recording devices. Period required to Reach the maximum temperature and ambient temperatureLoad factor or type of load. Connection diagram of bank and internal connection tap voltage. Burned coil. Date and time of burning. Installation site. Perod of use immediately after operation period.

Cause of failure:.


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