Contact opening

Provision must be made in the wiring to maintain power to the standby pump driver. This will prevent power interruption due to the pressure switch contacts opening when lubricant pressure is restored. Cycling of the standby pump will occur if the circuit is not maintained. A reset will have to be furnished to permit shutting down the standby pump when the main pump is back on stream. 

Energized, contacts closed. 2 Energized, contacts open. 3 Oe-energized, contacts closed. 4 De-energized, contacts open... 

The ability to coat a surface with a smooth film of constant thickness (conformity), and to fill a contact opening (interconnection)... 

In a further mask and etch process, a contact opening 13 is made down to the lower layer 9. The first mask is now removed by etching. Conductive metal connections 14 to 17 are then evaporated onto the device through a mask. 

Pressure switches are used to energize and de-energize electrical circuits when the process pressure reaches their set points. The standard switch contact configurations are shown in Figure 3.143. The contacts are designated as normally open (N/O) and normally closed (N/C). In case of a single-pole double-throw (SPDT) switch, as the process pressure reaches the set point, the N/C contact opens and the common (C) side of the switch is closed to the contact designated as N/O. 

The chlorine pressure switch senses the loss of chlorine gas pressure and its contacts open. After a snfficient time has elapsed to evacuate chlorine gas from the piping, an OFF delay relay, 3TR, is de-energized, closing the vacuum line valve. 

When the vacuum valve closes, its auxiliary contacts open causing interruption of the cir-cnits to the recirculation pump and pressure control pump motor starters. Auxiliary contacts in the starters open, intermpting the circuit to the seal flushing water solenoid valve and the remotely mounted control relay. The control relay is de-energized stopping the feed pump and macerator. 

Pump suction pressure switch contacts opened. Break or leak in chlorine vacuum line piping. 

Three important steps must be considered after the contact openings have been etched ... 

Another solution to reduce the loading effect was investigated by van Laarhoven et. al.61, (see figure 2.19). In their approach there was a 0.3 urn PECVD silicon nitride layer deposited atop the oxide prior to the contact opening. The normal procedure of adhesion layer (TiW), tungsten deposition and etch back was followed. Since the nitride etches with about the same rate as the tungsten (selectivity W SiN=0.8) both the loading is... 

Next, the sacrificial layer is deposited as a TEOS (Tetraethylorthosilane) oxide about 1.5 pm thick and is coated with photoresist, patterned and etched to form contact openings to the buried polysilicon layer (Fig. 5.3.11b). 

Two ways in which catalytic oxidation for control of trace VOCs can be carried out are shown in Figure 1. The first uses a direct contact open flame to preheat" the gas stream upstream of the catalyst. In this configuration, the open flame both preheats the gas stream to an elevated temperature so catalytic oxidation can take place and actually accomplishes some measure of VOC oxidation. This preheat" flame may accomplish a significant portion of the overall observed oxidation. The chemical mechanism of open flame oxidation involves free radical-induced homogeneous reactions and is fundamentally different from heterogeneous catalytic oxidation, which involves activated complexes formed on the catalyst surface. The second method involves only a catalyst bed, over which the gas stream passes, usually after some indirect preheating. The difference between these two configurations is the presence of an open flame, but this difference can be important because the mechanism of oxidation on a catalyst in close proximity to a flame may be different from that on a catalyst by itself. 

Diverse techniques of wireless transmission exist, for example, infrared or radio operator waves using various standards (IEEE 802.11, Bluetooth). If these modes of transmission free communicative clothing from the need for physical connections, several additional constraints must also be taken into account. For example, the energy consumption necessary to their operation may be important. Moreover, when it is a question of simple information transport (like a contact open or closed or similar), or of energy transport, wired connections become indispensable. The wireless connections mainly have to be used to connect the user to the external environment. 

When dealing with instruments, determination of output contact shelf position may be more difficult. An example of such an application is a contact shown as normally open with a subscription like "O, C, C, O." This would indicate a normally open contact (shelf position), contact closes when the instrument is powered up, contact remains closed during in-range sensing, contact opens on out-of-range sensing (e.g., shutdown). 

WHEN ANY TWO CONTACTS OPEN OUT OF FOUR CONTACTS POWER FLOW WH.L BE STOPPED TYPICAL 2004 CONFIGURATION OF NUCLEAR PLANT PROTECTION. 

In the case of de-energize type logic set of contacts, opens to trip or shutdown the system (in case of energize to trip logic, contact closure will be considered for trip also series, parallel configuration types will be reversed). When trip is associated with proper cause it is safe failure. When this is NOT, then it is spurious/nuisance trip or shutdown. As per lEC 61508 Demand or failing element commands output to a safe state. 

ANY 2003 CONTACTS OPEN OUTPUT 0=0, NOT P USED FOR DE ENERGIZE TO TRIP LOGIC... 

Fig. 7.10 Scheme of the microcantilever fabrication process (a) oxidation, aperture, and doping (b) contacts opening (c) aluminum or gold deposition (d) front-face etching (e) back-side etching [Reprinted with permission from Urbiztondo et al. (2009). Copyright 2009 Elsevier]... 

The function of the control system is to regulate the operation of the pump. The latter pumps fluid from an infinitely large reservoir into the tank. We shall assume that it takes 60 s to pressurize the tank. The pressure switch has contacts, which are closed when the tank is empty. When the threshold pressure has been reached, the pressure switch contacts open, de-energizing the coil of relay K2 so that relay K2 contacts open, ranoving power from the pump, causing the pump motor to cease operation. The tank is fitted with an outlet valve that drains the entire tank in an essentially negligible time the outlet valve, however, is not a pressure relief valve. When the tank is empty, the pressure switch contacts close, and the cycle is repeated. 

Initially, the system is considered to be in its dormant mode switch 51 contacts open, relay Kl contacts open, and relay K2 contacts open that is, the control systan is deenergized. In this de-energized state, the contacts of the timer relay are closed. We will also assume that the tank is empty and the pressure switch contacts are therefore closed. 

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