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Generators & Motors

Thermography

Thermography is the use of Infrared photography to measure thermal energy from an object. Thermal energy shows us a new picture to us- the one which is not visible with naked eye

Benefits of Infrared Thermography

• Prevent -  In one step you can increase equipment efficiency and the safety of your facility- a potentially save your company cost of a major electrical malfunction
• Diagnose – by using thermographic photography, we can look inside at the performance of many different systems and make recommendations that will increase the performance of your business
• Repair – NDL has been providing electrical maintenance and repair since 1990. Safety is our no. 1 priority, so you can assure your elitrical work is completed with all the safety standards

Vibration Analysis

Partial Discharge

The electrical stress within the insulation system is never uniform. Material with low dielectric current is more stressed. If the stress increases beyond a limit then a partial insulation failure occurs. Since the discharges occur partially in the insulation system, they are known as partial discharge. Partial Discharge can occur due to the improper design, manufacturing and also the various service conditions.

So we can say when discharges occur not directly between the electrodes but in the part of insulation system, they are called partial Discharge.

The transformer insulation is a combination of oil and paper. Occurrence of PD in the transformer produces various problems. In solid insulation, it can create discharge trees, which reduces the insulation strength. In liquid insulation like oil it creates gas bubbles.

Signature Analysis

Harmonic Measurement

Tan Delta & Capacitance

Every Power electrical appliances in use, undergo stress from Operating Voltage, Mechanical Vibration, Temperature, Gaseous and Solid Metallic Impurities. Under these stress, the degradation of the insulation takes place, in the Electrical equipment. This  stress lead to the continuous ageing of the appliance, with regard to its Electrical Properties. Sometimes there will be an avalanche of Insulation breakdown.  In the total complex network of Power Generation, Transmission, Distribution System ageing of a simple insulation may lead to a disastrous breakdown of the system, causing heavy loss.

To avoid such unexpected breakdowns and for the un-interrupted service, from electrical power  it is very essential to know the insulation quality of the equipment that is going to be used in the power system. And it is also essential to periodically monitor the Insulation property of equipment, that in use in this Power Network.

In Electrical AC System the Dissipation Factor Tan ? or Power Factor Cos ø is considered as the indicator of quality of insulation.

Applications of Tan delta

• Transformers
• Generators
• CT/CVT
• Motors
• Breakers
• Cables

Insulation Resistance

It is desirable to have Insulation Resistance as high as possible consistent with acceptable mechanical, chemical and heat resisting properties.

This test is to detect the conductive impurities or mechanical imperfections in the dielectric which affect the quality of insulation which may be developed in the dielectric during the manufacturing process.

The insulation resistance test can detect if this connection is loose. It can also detect whether there are other, undesired and inadvertent, grounds. If the intentional core ground is intact, the resultant resistance should be very low. To check for unintentional core grounds, remove the intentional ground and Megger between the core and the grounded transformer tank. This test should produce very high resistance indicating that an unintentional ground is not present. This test is to supplement DGA that shows generation of hot metal gases (methane, ethane, and ethylene) and to indicate if a spurious, unintentional core ground is the problem. Experience can help locate the source of the problem.

Polarization Index

Polarization Index test that it can provide an indication of insulation quality in ten minutes for very large equipment that might take very long time to get fully charged.

DC resistance

Leakage Current

The Leakage Current Test helps us in prediction of Break Down Voltage so as to take the preventive steps well in advance at an early stage of development

DC Absorption

DC Absorption Test indicates the insulation Condition of the Winding and Supplements to to various other Insulation measurements, therefore, if analyzed, based upon its trend over a period of Time, helps in making decisions better.

Surge Comparison Test

HI-POT Test