A Comparative Study of the Voltage Sag Propagation under Un-Symmetrical Faults through Distribution Transformer on Low Voltage Power Network

In this paper, the characterization of the voltage sag propagation under unsymmetrical faults through distribution transformer for low voltage power network is tested with the help of a power analyzer, which is based on sequence components. The voltage sag is a big issue of the power quality (PQ) for the power system networks, which must be analyzed and characterized for the suitable protection schemes and the control strategy, separately. In this study, the voltage sag characterization is fully examined under the unsymmetrical faults through the delta-star with ground (D-Yg) connection, which is commonly imlemented in the distribution power transformers. The MATLAB/Simulink and power analyzer tools are used to characterize the voltage sag propagation. The power analyzer works on the symmetrical sequence component’s method of the voltage. Moreover, the phasor diagram of the voltage sag is also given in this paper for better understanding. The obtained results would help in the design of the protection schemes for low-voltage and controlling the impact of voltage sag through filters.

Non-Directional Earth Fault Passage Indication in Isolated Neutral Distribution Networks

In this paper, two new methods for locating single-phase to ground faults in isolated neutral distribution networks are proposed. The methods are based on the analysis of symmetrical sequence currents. They are solely based on currents, not requiring voltage measurement. The first method employs only the zero sequence current and the second one utilizes the negative sequence current in combination with the zero sequence current. It is revealed why using only zero sequence current with a simple threshold is insufficient and may lead to false results. Using the proposed methods, earth faults with high resistances can be located in isolated neutral distribution networks with overhead lines or cables.

Dual functions of a cis-acting element within the rat prolactin gene promoter

Within the promoter region of the rat prolactin gene lies a TA-rich imperfect palindrome. The possible functions of the 18-base-pair symmetrical sequence were investigated by using an in vitro transcription system. Prolactin templates with and without the palindrome were transcriptionally assayed in both pituitary and nonpituitary extracts. Our results indicated that the palindromic sequence has at least two functions in the regulation of prolactin transcription.

Dual functions of a cis-acting element within the rat prolactin gene promoter.

Within the promoter region of the rat prolactin gene lies a TA-rich imperfect palindrome. The possible functions of the 18-base-pair symmetrical sequence were investigated by using an in vitro transcription system. Prolactin templates with and without the palindrome were transcriptionally assayed in both pituitary and nonpituitary extracts. Our results indicated that the palindromic sequence has at least two functions in the regulation of prolactin transcription.

Conformation takes precedence over sequence in adeno-associated virus DNA replication

Deletion of an 11-base symmetrical sequence in the inverted terminal repetition of the adeno-associated virus 2 genome inhibits DNA replication. Substitution of either an 8- or a 12-base symmetrical sequence unrelated to the original 11-base sequence restores DNA replication.