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Systems and transducers
Published in Charlie Cullen, Learn Audio Electronics with Arduino, 2020
There are many types of switch, but they all effectively change an open circuit into a closed circuit by closing some form of electrical contact (we learned about open circuits in the previous chapter). The push-button switch is often referred to as a momentary action switch, because electrical contact is only made during the moment that mechanical force (e.g. finger pressure) is applied. This type of switch is commonly used in computer keyboards, and at a basic level the same trigger is used in synthesizer keyboards and other MIDI controllers (though they also incorporate more advanced velocity and pressure sensors made from piezoelectric materials). Toggle switches, as the name implies, toggle between open and closed states – such as the on/off switch on an amplifier. Rotary and joystick switches effectively combine more than one switch within a single component, allowing either multiple outputs (rotary) or multiple switches (joystick) to be engaged with a single movement. We can also describe a switch by the number of poles (circuits) and throws (output paths) it has (Figure 2.21).
Actuators
Published in Volker Ziemann, A Hands-On Course in Sensors Using the Arduino and Raspberry Pi, 2018
The terminals on the high-power side can handle both AC and DC voltages. The relay is very similar to a normal switch in the way that it establishes an electrical contact between two terminals. In Figure 3.5, it closes or opens the contact between the AC supply and a lamp, but the lamp can be replaced by any other device that needs to be turned on and off.
Faults and Protection of Electric Energy Systems
Published in Mohamed E. El-Hawary, Electrical Energy Systems, 2008
A relay is a device that opens and closes electrical contacts to cause the operation of other devices under electric control. The relay detects intolerable or undesirable conditions within an assigned area. The relay acts to operate the appropriate circuit breakers to disconnect the area affected to prevent damage to personnel and property.
A numerical study on contact conditions, dynamic resistance, and nugget size of resistance spot weld joints of AISI 1008 steel sheets
Published in Numerical Heat Transfer, Part A: Applications, 2023
Prashanth Kumar Reddy Gillela, Jeevan Jaidi, Venugopal Gude, Sunil Kumar Pathak, Dinesh Srivastava
The electrical potential field governed by the current density is expressed as, The resistive heat generation per unit volume and unit time is expressed as, The voltage difference across the interfaces is expressed as [28], where, ECR is electrical contact resistance and is related to electrical contact conductance (ECC) as, The electrical resistivity as a function of temperature is expressed as, where, is resistivity at reference temperature, and is temperature coefficient of resistivity.
Different-sized thermoelectric cooler modules operated by a thermoelectric generator system
Published in Numerical Heat Transfer, Part A: Applications, 2023
Ali Kürşad Arıcıoğlu, Gülay Yakar, Ali Gürcan
Chen et al. [25] developed a numerical method for modeling and estimating the performance of an integrated system to provide useful insight into the importance of geometric design for improving the performance of an integrated TEG-TEC system. In their study, they considered the effects of heat loss and electrical contact resistance on the performance. Their numerical estimates provided useful insight into the design of integrated TEG-TEC systems. Their results indicated that when the lengths of the TEG and the TEC were varied, the percentages of the maximum reduction in system performance were 12.45 and 18.67%, respectively. Hasani and Rahbar [26] submitted an experimental study to study the performance of a waste heat recovery system from a 5 kW PEM fuel cell by utilizing TECs. They also approached the laboratory test results and evaluated TECs potential to be used for heat recovery from the PEM fuel cell. Their study ensured an empirical relationship for the estimation of the heat recovery system voltage utilizing the leaving water temperature of the PEM fuel cell. They suggested an optimum range for external loads to obtain maximum heat recovery and power generation from TEGs.
Effect of Lubricant Properties and Contact Conditions on False Brinelling Damage
Published in Tribology Transactions, 2023
Rachel Januszewski, Victor Brizmer, Amir Kadiric
Experiments to investigate the influence of various lubricant properties and contact conditions on the damage due to small amplitude oscillating motion were performed using a PCS Instruments high-frequency reciprocating rig (HFRR) shown in Fig. 2. In this rig a 6-mm-diameter ball specimen is reciprocated against the flat surface of a disc under oscillating amplitudes as low as 20 μm. Oscillating motion is provided by an electromagnetic vibrator. The drive system permits variation in both amplitude and frequency of oscillation and the normal load is varied mechanically using weights. A linear variable differential transducer measures linear displacement in order to control the stroke length, and a fretting flexure lock ensures accuracy at stroke lengths below 100 μm. The temperature of the test cell is controlled through a heater block. The system records frictional force and electrical contact resistance. The electrical contact resistance provides an indication of the prevalent lubrication conditions in the contact throughout the tests (20), which greatly aids the interpretation of observed fretting wear trends.