Constant supply voltage

Shunt-Wound Motors. These motors operate at approximately constant speed regardless of variations in load when connected to a constant supply voltage and with fixed field excitation. Maximum decrease in speed as load varies from no load to full load is about 10-12%. 

There are, however, numerous cases where electronegative additives can act as promoters for catalytic reactions. Typical examples are the use of Cl to enhance the selectivity of Ag epoxidation catalysts and the plethora of electrochemical promotion studies utilizing O2 as the promoting ion, surveyed in Chapters 4 and 8 of this book. The use of O, O8 or O2 as a promoter on metal catalyst surfaces is a new development which surfaced after the discovery of electrochemical promotion where a solid O2 conductor interfaced with the metal catalyst acts as a constant source of promoting O8 ions under the influence of an applied voltage. Without such a constant supply of O2 onto the catalyst surface, the promoting O8 species would soon be consumed via desorption or side reactions. This is why promotion with O2 was not possible in classical promotion, i.e. before the discovery of electrochemical promotion. 

From the electrical point of view, the theoretical minimum switching time is limited by the maximum power supply voltage and by the time constant LjR of the magnet with resistance R and inductance L. In a basic circuit like that shown in Fig. 10 with a fixed power supply voltage V, when the switch trips on, the current evolves according to the equation ... 

Here k is the proportionality constant between field and current (B = kI), Vp and Htv are the maximum positive and maximum negative power supply voltage, L and R are the inductance and resistance of the magnet, B is the instantaneous main field value, Su = (kIL)Vp and Sd = (kIL)Vn are the up-going and down-going slewing rates when B = 0, and a = R/kL. 

Internal reference Supplies a constant equilibrium voltage. 

The Mossbauer transmission spectra were recorded in the constant acceleration mode with an Elscint Mossbauer drive unit and a model MFG 3A Elscint function generator, an MVT-3 linear velocity transducer and an MD-3 transducer driving unit, y-ray detection was done with a Reuter-Stokes Kv-CH4 proportional counter driven by an Ortec 401A/456 high voltage power supply. Voltage pulses were introduced into an Ortec 142 PC preamplifier and an Ortec 571 spectroscopy amplifier. Data were collected on a Tracor-Northern NS-701A multichannel analyzer. The data were later analyzed on an IBM 360/370 computer. 

If an induction motor is run at a frequency below its normal operating frequency, the air-gap flux will rise if the supply voltage magnitude is kept constant. The rise in flux will cause magnetic saturation in the iron circuit of the motor and this in turn will cause a very large increase in magnetising current in the branch shown in Figures 5.1 or 15.11. 

From the mains and our use of batteries, we are well acquainted with the constant amplitude voltage supply. The ideal voltage supply has zero internal resistance. It supplies the set voltage from no load (load resistance oo, open circuit) to full load (minimum load resistance and maximum current). Two ideal voltage sources cannot be coupled in parallel. In series, the voltages are added. 

We realize from these equations the important difference between using a constant amplitude current or a constant amplitude voltage supplying a variable load resistance. 

The circuit of (b) can be used also as a constant current circuit. A constant amplitude voltage and a resistor are used to supply the input current. The load is the feedback resistor the constant input current will pass the feedback resistor for any resistance value up to the voltage limit of the operational amplifier. In this way, we can measure the current without any shunt. 

Round-the-clock measuring of electric currents in interelectrode spacing filled with high purity water and at constant stabilized voltage supplied to electrodes forms the basis of method of water conductive properties monitoring. The experiments have been performed at the plant described in Ref [9]. 

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