Relay circuit

V, = maximum voltage developed across the relay circuit by the other group of CTs during a severe most through fault,... 

But this may not always be true, as it is possible that one or more CTs in the faulty circuit may saturate partially or fully on a severe through-fault and create a short circuit (T 2 = 0) across the magnetizing circuits of all the CTs that are saturated. Refer to Figures 15.26(a) and (b). The CTs resistances, however, will fall across the relay circuit. Assuming that the other sets of CTs in the circuit remain functional, this would cause a severe imbalance and result in a heavy imbalanced current through the relay and an unwanted trip. Under such a condition. 

V = theoretical maximum CTsecondary voltage across the relay circuit at the maximtim internal fault current. (The maximum internal fault current is the level of fault of the machine or the system tinder protection.) This must also take into account any other supply sources that may also feed the fault, such as more than one supply bus, as shown in Section 13.4.1 (5) and Figure 13.18, and illustrated in Figure 15.30. If the cumrilative fault current is /scc> hen the maximum CT secondary voltage will be k m = Ascc impedance of the relay circuit. 

Vp = peak voltage across the relay V p = theoretical maximum CT secondary voltage across the relay circuit at the maximum internal fault current... 

Data Summaries of Licensee Event Reports at U.S. Commercial Nuclear Power Plants (Vanous Components) Nuclear 11209 one-fine event descriptions on specific component types failure rates and error factors Pumps, valves, diesels inverters, relays, circuit breakers (in separate reports) 100. 

DATA BOUNDARY Pumps,valves, diesels inverters, relays, circuit breakers... 

Wendlandt (45) used a microscopic method for the determination of the reflectance of the sample. The apparatus, as shown in Figure 9.28, consisted of a low-power (100 x, generally) reflection-type microscope, A, which is illuminated by means of a monochromator, B. The reflected radiation is detected by a photomultiplier tube, C, and amplifier, D, and recorded on either an X-Y recorder, E, or a strip-chart recorder, F. In order to heat the sample to 250°C, a Mettler Model FP-2 hot stage, G, is employed. Either isothermal ( 1CC) or dynamic sample temperatures may be attained by this device. The sample is moved through the illuminated optical field by means of the reversible motor, H. The motor is reversed at preset intervals by a relay circuit and timer, J. Thus, it is possible to scan the reflectance from the sample, which may consist of a single crystal or a powdered mixture. Powdered samples may be placed directly on the heated microscope slide or... 

Fig. 13.5 Instrumentation for critical evaluation of the Karl Fischer water method, (a) Amperometric circuit (b) relay circuit for automatic burette control (c) potentiometric circuit. (Reproduced from [58] with permission of the American Chemical Society).

Connectors, terminal strips, bobbins, switches, relays, circuit boards... 

A relay tripping circuit has been proposed by Manufacturing to eliminate the use of the electronic amplifier Ich exhibits non-fail—safe characteristics. This relay circuit is stxggested... 

The instrument bus furnishes power to those instruments most sensitive to disturbance while the relay bus (also called the "control bus") furnishes power to the less sensitive components, such as relays and motors, which not only are less sensitive to disturbance but are themselves actual sources of disturbance. If one of the alternator supplies breaks down or otherwise becomes unavailable, the relay bus would be switched to purchased power. To permit operation with the "rougher" purchased power, the relay circuits include a 2-sec timer and a number of time delay relays so that reactor shutdown does not ensue unless the r.elay bus voltage is off for 2 sec or longer. 

To control the polarity of each electrode independently, a relay circuit is made and connected... 

The solenoid valve array with necessary relay circuits and the controller are integrated together to produce a single stand-alone pneumatic pump controller unit. For the compressed air supply, a separate pressure tank or air compressor is needed. A pressure regulator with air filter is located between the air supply and the vale manifold. 

PPS (40% glass fibre) Boxes for electronic circuits, relays, circuit breakers, terminal blocks, connectors and electronic motor housings... 

PPS, glass fibre and bead reinforced Automotive head lamps, under bonnet parts exposed to oil, petrol and hydraulic fluids, pumps, valves, precision mechanical parts Boxes of electronic circuit relays, circuit breakers High heat applications High chemical resistance applications... 

Vox Avoice-operated relay circuit that permits the equivalent of push-to-talk operation of a transmitter... 

Fig. 12.1 A basic relay circuit, shown with both types of symbols.

The circuit of Fig. 12.3 illustrates how a relay circuit can translate binary numbers back into decimal, at least up to the number 4. The table below it shows the translation. For example, if relays B and C are activated by switches, then light bulb 3 will glow. This is not a practical circuit, but it illustrates the general idea of how some types of translators work. 

Fig. 12.6 A latching relay circuit, used as a circuit breaker.

The switching transition, once the positive feedback starts to take effect, is much faster than the charging of the capacitors. Therefore the switching action can be completed, long before the negative feedback from other half of the circuit will reverse things. This is similar to the relay circuit, where the armature motion is much faster than the charging of the capacitor. 

The remainder of the fault tree goes into further detail about how relay circuit can fail. In Figure 7.7, the fault tree has been simpMed and the Boolean expressions developed ... 

There are three identical reactor regulating channels each having a provision for median derivation The system has been designed such that failure of any one channel, automatically transfers the control to the remaining two. For this change over relay circuits have been used. 

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