Resolution of high vibration on a Generator

Case StudyThis is a synchronous generator driven by a GT through a speed reduction gearbox with a rated power of 25 MW(3600 rpm). Generator bearing high vibration levels resulted in several machine trips during the startup attempt followed by a unit shutdown caused by high lube oil temperature. Generator bearings were replaced, exciter misalignment was rectified and insitu balancing of generator rotor was attempted by plant maintenance personnel but did not yield desirable results preventing machine from attaining FSNL speed with acceptable vibration levels.Data indicated dominant 1X amplitudes up to 90 mm/sec Pk at generator inboard bearing confirming generator rotor unbalance coupled with high degree of anisotropic stiffness between horizontal and vertical planes. This case intends to detail how the high vibration issue was successfully diagnosed using various plots from different machine states and resolved by correct insitu balancing approach coupled with bump test technique to identify and eliminate structural resonance

Resolving High Vibration On a Vertical Pump

Case StudyHigh vibration were observed on the motor, pump,structure for more than 2 years with 1X dominant motor vibration. Assuming that the issue is of complete structural issue even though this motor was running well in the past, some structural modifications have been carried out at site which includes a welding a mass of 100 Kg on the structure in addition to the installation of braces to the structure which did not yield any positive results. Structural measurement along with the ODS carried out at site did not reveal a significant issue with the structure itself except for the structural natural frequency slightly closer to the running frequency of the motor. The decision to carry out an onsite balancing on the motor which was intended to remove the excitation force yielded good results which exposed additionally a mistake in the balancing activities carried out by a local vendor at work shop

The Intensity of Social Networks Group Use among the Students of Jordanian Universities

The paper investigates the intensity of (Social Networking Sites) SNSs use among the students of Jordanian universities. Four universities were involved in this study, while 727 undergraduate students respond to a questionnaire that measured their intensity of SNSs use. To answer research questions, the researchers used descriptive statistics, ANCOVA, Chi-Square, and T-test. The data analyses revealed significant differences among students' uses of SNSs. The variables consisted of university, faculty, gender, and year level. The study recommendation was the focus on integrating SNSs within learning management systems

Resolution of Non Repeatable Synchronous Rotor Response of a Power Generator Due to Sand Ingress

Case Studie

Resolution of high vibration on a Generator

Case StudyThis is a synchronous generator driven by a GT through a speed reduction gearbox with a rated power of 25 MW(3600 rpm). Generator bearing high vibration levels resulted in several machine trips during the startup attempt followed by a unit shutdown caused by high lube oil temperature. Generator bearings were replaced, exciter misalignment was rectified and insitu balancing of generator rotor was attempted by plant maintenance personnel but did not yield desirable results preventing machine from attaining FSNL speed with acceptable vibration levels.Data indicated dominant 1X amplitudes up to 90 mm/sec Pk at generator inboard bearing confirming generator rotor unbalance coupled with high degree of anisotropic stiffness between horizontal and vertical planes. This case intends to detail how the high vibration issue was successfully diagnosed using various plots from different machine states and resolved by correct insitu balancing approach coupled with bump test technique to identify and eliminate structural resonance

Resolving High Vibration On a Vertical Pump

Case StudiesThere is a single stage vertical pump installed in Acetic Acid area in a petrochemical plant. The unit is vertical high pressure (HP) reactor feed pump (High speed single stage, 230 kW, 12338 rpm & 3.444 gear ratio) driven by induction motor through a flexible shim pack coupling. High vibration levels were observed on the motor, pump and structure for more than 2 years with 1X dominant vibration (1X motor dominant frequency). Assuming that the issue is completely structural as this motor was running well in the past, there were some structural modifications have been carried out at site with inadequate engineering calculations. The modifications were welding a total mass of 100 kg onto the structure and the installation of braces to the structure which did not yield any positive results. A systematic structural measurement along with the Operating Deflection Shape carried out at site with the help of experts did not reveal a significant issue with the structure itself except for the structural natural frequency being slightly closer to the running frequency of the motor. The timely right decision by the experts to carry out an onsite balancing on the motor, which was intended to remove the excitation force, yielded good results which exposed a mistake in the balancing activities carried out by a local vendor at work shop. This case study is designed to outline how the high vibration issue was successfully diagnosed using various tests on site including the operating deflection shape, the root cause for the high vibration and finally how it was mitigated

Resolving High Vibration On a Vertical Pump

Case StudyHigh vibration were observed on the motor, pump,structure for more than 2 years with 1X dominant motor vibration. Assuming that the issue is of complete structural issue even though this motor was running well in the past, some structural modifications have been carried out at site which includes a welding a mass of 100 Kg on the structure in addition to the installation of braces to the structure which did not yield any positive results. Structural measurement along with the ODS carried out at site did not reveal a significant issue with the structure itself except for the structural natural frequency slightly closer to the running frequency of the motor. The decision to carry out an onsite balancing on the motor which was intended to remove the excitation force yielded good results which exposed additionally a mistake in the balancing activities carried out by a local vendor at work shop

Acquisition of Arabic Students with Hybrid and Receptive Learning Models

This study aimed to analyze the ability to acquire Arabic as a second language for students of the Islamic Economics and Business Faculty at IAIN Ponorogo through hybrid and sensory learning activities. This research is qualitative with a case study type. The research population totaled 176 students, with a sample of 20 students. The sampling technique was done by non-probability sampling with the snowball sampling method because the samples were taken based on the needs of this study. The research data is in the form of pronunciation of vocabulary sounds, Arabic spelling of letters, verbs, and nouns, the ability to understand the material being listened to, and the ability to read Arabic texts for FEBI IAIN Ponorogo students in odd semesters of 2022/2023 academic year. The student reading source used as research data is the book "Al-'Arabiyyah fī Dirāsah al-Mu'āmalāt." A book taught in the course "Arabic for Economics." Observation, interviews, and documentation carry out data collection techniques. Data analysis techniques with data reduction, data presentation, concluding, and verification. The results of the study show that the acquisition of Arabic as a second language by students of the Islamic Faculty of Economics and Business at IAIN Ponorogo in attending "Arabic for Economics" courses tends to differ from one another. They are entering the pre-production language acquisition phase. That is, they have not mastered many foreign vocabulary. This is due to the educational background taken before they entered university. Another influencing factor is the environment in which students live

Resolving High Vibration On a Vertical Pump

Case StudiesThere is a single stage vertical pump installed in Acetic Acid area in a petrochemical plant. The unit is vertical high pressure (HP) reactor feed pump (High speed single stage, 230 kW, 12338 rpm & 3.444 gear ratio) driven by induction motor through a flexible shim pack coupling. High vibration levels were observed on the motor, pump and structure for more than 2 years with 1X dominant vibration (1X motor dominant frequency). Assuming that the issue is completely structural as this motor was running well in the past, there were some structural modifications have been carried out at site with inadequate engineering calculations. The modifications were welding a total mass of 100 kg onto the structure and the installation of braces to the structure which did not yield any positive results. A systematic structural measurement along with the Operating Deflection Shape carried out at site with the help of experts did not reveal a significant issue with the structure itself except for the structural natural frequency being slightly closer to the running frequency of the motor. The timely right decision by the experts to carry out an onsite balancing on the motor, which was intended to remove the excitation force, yielded good results which exposed a mistake in the balancing activities carried out by a local vendor at work shop. This case study is designed to outline how the high vibration issue was successfully diagnosed using various tests on site including the operating deflection shape, the root cause for the high vibration and finally how it was mitigated