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C&G Unit 302: Principles of electrical science
Published in Trevor Linsley, Advanced Electrical Installation Work, 2019
The three-phase windings of an a.c. generator may be star connected or delta connected, as shown in Fig. 3.28. The important relationship between phase and line currents and voltages is also shown. The square root of 3 (3) is simply a constant for three-phase circuits, and has a value of 1.732. The delta connection is used for electrical power transmission because only three conductors are required. Delta connection is also used to connect the windings of most three-phase motors because the phase windings are perfectly balanced and, therefore, do not require a neutral connection.
Electrical science and principles
Published in Trevor Linsley, Electrical Installation Work Level 2, 2019
The three-phase windings of an a.c. generator may be star connected or delta connected as shown in Fig. 2.79. The important relationship between phase and line currents and voltages is also shown. The square root of 3 (√3) is simply a constant for three-phase circuits, and has a value of 1.732. The delta connection is used for electrical power transmission because only three conductors are required. Delta connection is also used to connect the windings of most three-phase motors because the phase windings are perfectly balanced and, therefore, do not require a neutral connection.
C&G Unit 202: Principles of electrical science
Published in Trevor Linsley, Basic Electrical Installation Work, 2018
The three-phase windings of an a.c. generator may be star connected or delta connected as shown in Fig. 2.54. The important relationship between phase and line currents and voltages is also shown. The square root of 3 (√3) is simply a constant for three-phase circuits, and has a value of 1.732. The delta connection is used for electrical power transmission because only three conductors are required. Delta connection is also used to connect the windings of most three-phase motors because the phase windings are perfectly balanced and, therefore, do not require a neutral connection.
Lateral Stability Limits for RC Wall Boundary Zones Based on Axial Response of Idealized Prisms
Published in Journal of Earthquake Engineering, 2022
R. A. Gokhale, M. Tripathi, F. Dashti, R. P. Dhakal
To further explore the effect of slenderness on the response of prisms, results of prism tests conducted by other researchers are sourced from literature, as presented in Table 4. Only the experimental programs that had uniaxial cyclic loading protocol and two layers of longitudinal reinforcement are considered. Since these experimental programs involved different support conditions, considering the prism slenderness (Hprism/b) would not facilitate fair comparison. Therefore, effective prism slenderness (kHprism/b = Lo/b) was deemed appropriate to compare the test results with different support conditions. The coefficient “k” adopted for pinned-pinned, partially fixed, or fixed-fixed support conditions was 1.0, 0.85 or 0.6, respectively. Although current experimental campaign revealed that the coefficient “k” for the fixed boundary conditions varied between 0.5 and 0.6, using the upper bound (i.e., conservative) value of k = 0.6 was deemed appropriate. Haro, Kowalsky, and Chai (2017) also observed in their tests that the coefficient “k” for fixed-fixed support condition could be approximated by the inverse of square root of 3 (i.e., k ≈ 0.58).
Calibration of the Frame Rate of High-Speed Digital Video Recorders by Stationary Counting Method: Application of the Stroboscopic Effect
Published in NCSLI Measure, 2018
H. W. Lai, Michael W. K. Chow, C. K. Ma, Aaron Y. K. Yan
This section shows the evaluation of the measurement uncertainties in accordance with “Guide to the Expression of Uncertainty in Measurement” (GUM). The standard measurement uncertainty for the two components, u(fs) and u(Sc), are derived as follows. u(fS): It arises from the uncertainty in the output signal frequency of the signal generator which is phase locked to the SCL cesium frequency standard. The relative standard measurement uncertainty at 10 kHz is 2.9 × 10−11. It has a normal distribution and its degree of freedom is assigned to be infinity.u(SC): It arises from the resolution of the 10-LED C-display. The time difference between two LED positions equals to one period of the clock input which is 0.1 ms for a 10 kHz clock. The video is recorded for a duration of 2 s, therefore the C-display resolution is translated to that in relative frequency of 0.1 ms/2 s = 5 × 10−5. At a nominal frame rate of 1000 fps, this becomes 0.05 fps. It has a rectangular distribution and the standard measurement uncertainty equals to 0.05 fps divided by square root of 3, which gives u(SC) = 0.0289 fps. Its degree of freedom is assigned to be infinity.