Silicon Control Rectifier SCR

If a third wire is attached to a PNPN, as indicated by the lower left diagonal dashed line, this triode acts like the two transistors of Fig. 21.2, with the new wire being like the terminal that was touched by the IK probe. That is, if the voltage 

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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 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. 

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. 

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. 

The Z-source DC circuit breaker basically consists of a silicon controlled rectifier (SCR) and two crossed L-C series connections. In case there is no fault, the SCR is on and the capacitors are charged by the voltage source. In steady state, the capacitor currents are zero, the voltages across the inductor vanish and a constant current fiows through the series connection of inductors and load. Suppose that the resistances of the inductors can be neglected and that the load is the parallel connection of a load resistor Rl and a load capacitor Cl - Then steady-state values are ... 

SCR drive A variable-speed motor drive widely used today on new extruders in which a silicon-controlled rectifier (SCR) converts alternating current to run a direct-current motor. Unlike AC motors, DC motors have good torque characteristics over a wide speed range. 

The three basic types of drives are alternating current (ac), direct current (dc), and hydraulic. While a number of drives have been used in extruders, the most common are dc silicon control rectified (SCR) and ac adjustable frequency drives. A dc SCR drive is a sohd-state dc rectifier connected to a dc motor. The base speed is about 1 percent, but reduces to 0.1 percent when a tachometer is added to the drive. These drives are very reliable, can handle high starting torques, can maintain a constant torque through a speed range of 20 1, and are relatively easy to maintain (that is, replace brushes). However, since the drives have brushes, they are limited to noncorrosive polymers. 

The three basic types of drives are alternating current (AC), direct current (DC), and hydrauhc. Although a number of drives have been used in extruders, the most common are DC silicon control rectified (SCR) and AC adjustable frequency drives. 

Control of electric power, or power conditioning, requires the conversion of electric power from one form to another, that is, DC to AC, one voltage level to another, and so on, by the switching characteristics of various electronic power devices. Some of these devices, such as silicon controlled rectifiers (SCRs),... 

Silicon-controlled rectifiers (SCRs) A control system utilized to control speed by modifying the sine wave profile of power to variable-speed ac motors. 

Battery-Electric Equipment. This is mechanically simpler in design than engine-driven equipment. Typically, the high-torque dc electric-drive motor is coupled directly to the drive axle through a constant-mesh drive train. An electronic silicon-controlled rectifier (SCR) speed-control device regulates the motor s revolutions per minute through operator foot control. Direction is reversed electrically with a delay interlock to avoid reversing motor direction while in motion. 

If the capacitor is wired to the output terminals of the solid-state motor control, damage will result to its silicon-controlled rectifier (SCR) power devices. 

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