alternative transients program atp rule book

MOSA has dynamic characteristics that are significant for overvoltages coordination studies regarding fast front surges.

Several models with acceptable accuracy have been proposed to study the frequency-dependent behaviour of MOSA.

These models differ in calculation and adjustment of the model parameters, some models needs iterative procedure and o the r models the necessary data are not reported in the manufacturers data sheets.

A simplified model by Pinceti has been used to study protection of overhead transmission line against direct lightning strike.

In this paper, simulations have been performed using the Alternative Transients Program version of Electromagnetic Transient Program (ATP-EMTP) and the results were compared with the ones of manufacturers data sheet and found to be satisfactory.

Pinceti model has a small relative error of 2.26 for fast transient surge (12s) and of 1.05 for slow transient lightning surge (820s) respectively when compared our results with the results from manufacturers data sheet.

The simulations were performed for a 3kV TRANQUELL MOSA and its effective protection when applied to the end of 1km line and lightning strike of 0.1120s a typical subsequent return stroke current was injected at the middle of the line.

It has been observed that, the significant dynamic characteristics of MOSA are that the peak of the voltage wave occurs before the peak of the current wave and that the residual voltage across the MOSA increases as the time to crest of the MOSA discharge current decreases.

INTRODUCTION Recently, the re has been growing concern over lightning caused damages, and disturbances on the consumer operated equipments utilizing a telecommunication line.

Voltage and current surges generated by lightning in modern electronic environment can cause failure, permanent degradation or temporary malfunction of electronic devices and telephone network system.

To minimize the threat imposed by surges, various transient protection models have been developed 3, 5, 6, 8.

Metal Oxide Surge Arrester (MOSA) is widely used as protective device against switching and lightning overvoltages in electronics and electrical systems.

They exhibit an extremely high resistance during normal operation and a very low resistance during transient overvoltages.

That is the voltage-current (V-I) characteristics of the MOSA is non-linear 1, 3, 5, 6, 8.

For fast front surges shorter than 8s, the dynamic effects play an important part.

In fact, the residual voltage increases as the time to crest of the current pulse decreases and the residual voltage peak anticipate the discharge current crest as well.

It is very of ten difficult to identify the dynamic model parameters from the available manufacturers data sheet.

Pinceti model 8 among o the rs mentioned models has a straight forward parameters computation method where all necessary data are reported on the manufacturers data sheets with no iteration correction procedure is required compared to Institute of Electronics and Electrical Engineers Working Group 3.4.11 (IEEE W.

G. 3.4.11) model 5.

The comparison of residual voltage calculated with the Pinceti model and the residual voltage reported in the manufacturers data sheet for a given current pulse show fair accuracy.

Simulation tools, such as the Alternative Transients Program version of Electromagnetic Transient Program (ATP-EMTP), are nowadays of standard application to evaluate overvoltages and insulation coordination in the power and telecommunication systems.

ATP-EMTP package has been used to study the effectiveness protection of the 3kV TRANQUELL MOSA when applied to the load end of the telephone line using Pinceti model.

Direct lightning strike is assumed to be terminated at the center of the 1km overhead transmission line which is 7m above ground.

Page 2 and 3: It should also be noted that for MO Page 4 and 5: 3 SIMULATION RESULTS The simulation Page 6: 4 General Electric Company, TRANQ.

Alternative Transients Program Atp Rule Book