Silicon-controlled

The silicon-controlled rectifier with a dc motor has become predominant in adjustable-speed drives for almost all commonly used conveyors when speed adjustment to process conditions is necessary. The low cost of this control device has influenced its use when speed synchronization among conveyors is required. This can also be done, of course, by changing sheave or sprocket ratios. 

Silicon-controlled rectifiers (SCR). These arc basictilly thyristors and unless specified, a thyristor will mean an SCR Triacs... 

NOTE Do not use snubber values or snubber elements intended for silicon-controlled rectifier (SCR) circuits in switching power supplies. The impedances and parasitic values of these circuits are much lower than within switching power supplies. They will create far too much loss in switching power supply circuits. 

The exciter is an AC generator with a stator-mounted field. Direct cur rent for the exciter field is provided from an external source, typically u small variable voltage rectifier mounted at the motor starter. Exciter oui put is converted to DC through a three-phase, full-wave, silicon-diode bridge rectifier. Thyristors (silicon-controlled rectifiers) switch the cur rent to the motor field and the motor-starting, field-discharge resistors These semiconductor elements are mounted on heat sinks and assembled on a drum bolted to the rotor or shaft. 

The laboratory layout is sketched in Fig. 15.4 The power supply is a 3-phase silicon controlled rectifier, SCR, controlled supply capable of delivering 200 A at 50 V. 

Some induction heating furnaces must operate at frequencies higher than the supply frequency. Formedy, rotating motor alternator frequency converters were used. Now the availability of high speed, high power silicon controlled rectifiers for use in frequency converters has made rotary converters obsolete. Modem units operate at higher efficiency, cost less, require less factory space, and coordinate readily with process controls (2). 

NUCLEOPHILIC DISPLACEMENT AT SILICON CONTROLLING FACTORS OF THE STEREOCHEMISTRY... 

Testing of Diodes, Silicon Controlled Rectifiers, Transistors and Integrated Circuits , PATR 4692 (1974) 25a) T. Shiki et al, Gas-Pro-... 

Hwu et al. have examined the dependence of the metal oxidant on the mode of reactivity in silicon-controlled allylation of 1,3-dioxo compounds [95JOC856]. The use of manganese(III) acetate furnished the dihydrofuran product 22 only. On the other hand, use of cerium(IV) nitrate resulted in the formation of both acyclic (23) as well as the cyclized compound, with the product distribution dependent on the nature of the allylsilane. Facile synthesis of dihydrofurans by the cerium(IV) mediated oxidative addition of 1,3-dicarbonyl compounds to cyclic and acyclic alkenes has also been reported [95JCS(P1)187]. 

With the plethora of electronic timers and alarm watches on the market one would think it would be a simple task to adapt these units as demolition timers. Most of these devices do not put out sufficient energy to their alarm buzzers to reliably detonate an electric blasting cap. But it is not extremely difficult to modify them by using a Silicon-Controlled Rectifier (SCR) switching circuit. The PLO is known to have used timers adapted from a cheap digital alarm watch and a SCR in Lebanon. 

A triac may be perceived as opposing SCR s (semiconductor controlled rectifier or silicon controlled rectifier) in parallel, each activated by a gate current (Figure 2.12). Current can flow in only one direction through the diodes in Figure 2.12. Electrical power from a wall socket, conventionally 110 or 220 ac volts is fed into the device. The SCR s act like diodes in the sense that current is allowed to flow in only one direction. During one half of the cycle, the current may flow through one... 

Figure 1 shows the symbols of common elements used in electronic circuits. These can be classed as either passive components, such as resistors, capacitors, inductors, and diodes, or active components, such as bipolar and field-effect transistors, and silicon-controlled rectifiers (SCRs). Some of the key features and physical characteristics of these devices are summarized in the first two sections of this chapter. 

A temperature control technique utilizing the SCR (silicone-control led rectifier) which operates by means of the P (proportional), I (integral) and D (dilTerentia) control circuits.. 

Platform two contains a bank of SCRs (silicon controlled rectifiers), relays and voltage dividers. 

SCR 1, SCR2, SCR3, SCR4 - 35 amp silicon controlled rectifier, 600 PRV... 

Each heating zone is 20 cm in height, and the power to each zone is controlled by a silicon-controlled rectifier circuit. An additional flat plate heater is located at the bottom of the vessel. Furnace and reactor temperatures are recorded on a 12-point Barber-Colman chart recorder. 

Until the recent development of switched mode power supplies (SMPS), most industrial precipitators were energized from some type of 50-60 Hz rectified high voltage equipment. This basically comprised a suitably designed and insulated step-up transformer, the output from which can be controlled by employing silicon controlled rectifiers to modulate the incoming... 

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