Operational current-control circuit

Fig. 5.44 Current control circuit with the aid of an operational amplifier (a) and a circuit of galvanostat (b).

When the start button is pressed, current will flow from the brown phase through the control circuit and contactor coil to the grey phase which energizes the contactor coil and the contacts close, connecting the three-phase supply to the motor, as can be seen in Fig. 3.29. If the start button is released the control circuit is maintained by the hold on contact. If the stop button is pressed or the overload coils operate, the control circuit is broken and the contactor drops out, breaking the supply to the load. Once the supply is interrupted, the supply to the motor can only be reconnected by pressing the start button. Therefore, this type of arrangement also provides no-volt protection. 

Penetration of gas bubbles into the Luggin capillary can disturb the steady operation. In the worst case, the control circuit of the potentiostat will be interrupted and the cell current can increase... 

The electron accelerator employed has been an AS 2000 Van de Graaff accelerator manufactured by High Energy Corporation, Burlington, Mass. The electronic control circuit has been modified considerably, and at present, this accelerator is capable of delivering 30 ns to 5 ys electron pulses of 2 - 2.5 MeV energy and v 1.2 A current at a repetition rate of 60Hz or less. The accelerator can also be operated in the continuous beam mode. The focussed beam has a diameter of 0.3 cm at the output window. 

A device possessing electrical resistance used in an electric circuit for protection, operation, or current control. Eormation of superfine particles by Rapid Expansion of a Supercritical fluid Solution at the end of a NOZZLE. 

While there are many means by which the control rc-J lion taking place within the ionization chamber 200 rises, can be operated, it is believed sufficient to illustrate and As the ionization increases, the current passing through describe one simplified control circuit to the end that fully relay coil 206 also increases until a predetermined field equivalent circuits will be made apparent to those skilled -0 intensity is reached. When the induced magnetism in the in the art. relay coil 206 has reached a predetermined strength the... 

U sing OAs allows construction of potential and current control circuitry that operates more ideally than the simple voltage and current sources of Fig. 1 [2]. In voltage control appKcations, the use of an OA buffer between a voltage source and the cell replaces the internal resistance of the voltage source with the low-output impedance of the OA. However, a simple extension of the OA buffer permits elimination of a large fraction of the solution resistance of the electrochemical cell. This OA circuit is called a potentiostat or voltage clamp. 

Fig. 3 Scheme of potentiostatic operation for a preparative electrolysis, using in principle a simplified cyclovoltammetry equipment. The potential of the working electrode is measured by a Luggin capillary, coupled with a reference electrode (RE, see Sect. 2.5.1.6). The control circuit in the potentiostat adjusts the cell current until the potential of the working electrode is equal to the voltage at the control input. 

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