SAI ELECTRICALS: ON-LINE CONDITION MONITORING OF TRANSFORMER

Necessity of Online Conditioning & Monitoring of Transformer:

Since we know due to various stresses like electrical, mechanical, chemical and environmental factors effect the insulation of transformer.This deterioration will affect the performance of transformer. The environmental factors that effect the reliability of transformer.

System Voltage Variations : Voltage Variation of 8KV to 12.5KV in 11KV System and 28KV to 36Kv in 33KV System.

Frequency Variations : Variation in frequency from 48Hz to 51Hz.

Short Circuit Forces :Because of poor protection system short circuit are more frequent

Over Fluxing : Generation of over fluxing due variation in system voltage & frequency

Harmonics : Harmonics generation due to increase electronic usages(non ohmic appliances)

Inrush Current : Generation of inrush current during switching ON of transformer/ capacitors

Loading patterns that are variable : Unbalance loading patterns due to unbalance load.

Study the environmental factors in detail which are responsible for abnormal PPM level of Hydrogen

1)VARYING VOLTAGES & OVER FLUXING:

Over fluxing generally occurs at high voltages. At over fluxing voltages recording PPM level of H2 is important. If high voltages are very frequent than it is very likely that insulation failure may occur. So monitoring of PPM level of H2 gives us insight into deterioration. To avoid high voltage, voltage control becomes must by using OLTC etc. Below table showing some typical condition which are showing the change in H2 PPM level w.r.t change in voltage.

2) LOADING PATTERNS:

IS 6600 provides the guidelines for loading of transformers. In practice because of non availability of data it is impossible to follow these guidelines. With online monitoring system these guidelines can be followed accurately as software calculates and automatically informs any discrepancies.

In above representations we can record the data for oil temperature & winding temperature v/s. time.These all parameters are available on our dashboard and stored in our system. By analyzing the same we can take appropriate action if any abnormal condition has occurred.

3) SHORT CIRCUIT FORCES & INRUSH CURRENT:

We can collect the information about the event of short circuit current due to which temperature rise of transformer will increased Further during switching ON the transformer inrush current will drawn through the transformer, with the help of this graphical representation we can also collect the information about switching events and the effect on PPM levels of H2 and we can also take the necessary preventive & maintenance action.

ENERGY & POWER CHARGES SAVING

Energy (KVAH, KWH & Demand) Vs Time:In this graphical representationwe can analyze the time bound data for Energy (KVAH, KWH & Demand).We can also get the graphical representation in various combinations which will be helpful in condition monitoring and also help us to use maximum energy in lean period to save the energy & power charges.Some of the combinations are as below: