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Amplifiers and Filters
Published in Clarence W. de Silva, Sensor Systems, 2016
Proper grounding practices are important to mitigate unnecessary electrical noise problems and, more importantly, to avoid electrical safety hazards. A standard single-phase AC outlet (120 V, 60 Hz) has three terminals, one carrying power (hot), the second neutral, and the third connected to earth ground (which is maintained at zero potential rather uniformly from point to point in the power network). Correspondingly, the power plug of an instrument should have three prongs. The shorter flat prong is connected to a black wire (hot), and the longer flat prong is connected to a white wire (neutral). The round prong is connected to a green wire (ground), which at the other end is connected to the chassis (or casing) of the instrument (chassis ground). By grounding the chassis in this manner, the instrument housing is maintained at zero potential, even in the presence of a fault in the power circuit (e.g., a leakage or a short). The power circuitry of an instrument also has a local ground (signal ground), with reference to which its power signal is measured. This is a sufficiently thick conductor within the instrument, and it provides a common and uniform reference of 0 V. Consider the sensor signal-conditioning example shown in Figure 3.4. The DC power supply can provide both positive (+) and negative (−) outputs. Its zero-voltage reference is denoted by common ground (COM), and it is the signal ground of the device. The COM of the DC power supply is not connected to the chassis ground but connected to the earth ground through the round prong of the power plug of the power supply. This is necessary to avoid the danger of an electric shock. Note that the COM of the power supply is connected to the signal ground of the signal-conditioning module. In this manner, a common 0 V reference is provided for the DC voltage that is supplied to the signal-conditioning module.
Cables, conductors and conduits
Published in Ray Tricker, Wiring Regulations in Brief, 2020
A fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby interrupting the current.
A method for suppressing respiratory noise in impedance cardiography and comprehensive assessment of noise reduction performance
Published in Journal of Medical Engineering & Technology, 2022
Phan Dang Hung, Chu Quang Dan, Vu Duy Hai
To collect the data, we used equipment specifically designed in the previous research for simultaneously recording ICG and ECG signals [26]. The equipment is validated to obtain a similar signal to the signal generated from the impedance simulator. The equipment used the technology of direct digitisation of the modulated signal at a high frequency with a much lower sampling rate. In this way, the ICG signal could be measured without attenuating oscillations due to respiratory activities. The equipment has a sampling rate of 200 samples per second, A-D converter resolution of 16-bit, the sine-wave alternating current with a current amplitude of 1.5 mA, and frequency of 85 kHz for the excitation. The measurement circuit ensures electrical safety for measuring objects by the DC-DC converter (JHM1524D12, XP Power, China) power supply with voltage isolation of 4 kV, specifically designed for medical application. A simplified block diagram of the acquisition equipment used to collect data is shown in Figure 2.
Solutions to Reduce Leakage Current and Extend the Operating Range of Power Factor for a Single-Phase Full-Bridge Inverter with DC Bypass
Published in Electric Power Components and Systems, 2019
Woei-Luen Chen, Wen-Tao Su, Kun-Feng Chen, Chia-Ting Lin, Ming-Sheng Xu
Although direct grid penetration of PV power averts power losses from multiple energy conversion stages, two urgent concerns arise: the first is the grid voltage fluctuation due to the changing PV power feed-in on the low voltage grid and the second is the electrical safety arising from close proximity to residential areas. The first problem can be solved by permitting PV inverters with modest reactive power capability for keeping the voltage stable at the grid connection point and comply voltage quality stipulated in EN 50160 or IEEE Std. 519. Regarding the second issue of the PV inverters installation within the limited residential space, it follows that the higher switching frequency is desired for reducing the size of the component in the power circuit. However, the high frequency operation lessens the impedance of the parasitic capacitor between the PV array and the ground and consequently increases the possibilities for electrical hazards [1]. A typical method for the decrease in parasitic capacitor impedance is to augment the impedance along the path of leakage current. The coupled transformer featured with a galvanic isolation is the most representative to be widely employed either in AC circuit or DC circuit for suppressing the leakage current. But the price for using a transformer to reduce the possibilities for the electric shock is the bulky circuit volume and a decline in overall power efficiency.
Sustainable and flexible industrial human machine interfaces to support adaptable applications in the Industry 4.0 paradigm
Published in International Journal of Production Research, 2019
Aitor Ardanza, Aitor Moreno, Álvaro Segura, Mikel de la Cruz, Daniel Aguinaga
Both in immunity and emissions, radiated and conducted, the hardware platform complies with the general regulations UNE-EN 61000 and derived from CISPR 11, 14, 22 (UNE-EN 55014).Regarding electrical safety, it exceeds the stiffness, insulation and leakage current measurement tests defined by the UNE EN-60335 standard.In relation to climatic conditions, it surpasses the tests defined in the general regulation UNE-EN 60068 (extreme temperature, humidity, thermal shock, salt spray, etc.).Finally, the platform overcomes vibration tests, both random and sinusoidal, and shock according to the general regulations UNE-EN 60068 and others (MIL-STD-810).