De-energize

The pilot plant must also be carehiUy designed so that its control and safety systems are "fad-safe" and any unexpected equipment or utdity fadure brings the unit into a safe and de-energized condition. Unexpected or rapid process changes, if they can herald or lead to dangerous conditions (eg, mnaway exothermic reaction), should be continuously monitored by appropriate instmmentation and suitable automatic action provided (1,55—67). 

N = operation under rated conditions / = at rest and de-energized and 6, = temperature rise reached during one duty cycle ( -= 0)... 

This is a sequence of identical duly cycles, each consisting of a period of operation at constant load and a period of operation at no-load. The repeat load and no-load periods are just adequate to attain thermal equilibrium during one duly cycle. There is no rest and de-energizing period, (Figure 3.6). Unless otherwise specified, the duration of the duty cycle will be 10 minutes. 

If the cycle has a short-time rating, with a period of energization and one of rest, the motor will obviously cool during the de-energizing period, and depending upon the peak load and tlie rest periods, a comparatively lower output motor can perform duties at higher loads. The equivalent output for the load cycle of Figure 3.16 is... 

The function of a shunt trip coil is to trip an intetrupter. As. soon as its coil is energized, it releases the closing lever of the interrupter and trips it. The coil is rated for a short time, since it is in the circuit for a very, short period only when it is required to trip the interrupter. To ensure that it does not continue to remain energized after carrying out its function, the interrupter s NO contacts are also wired in scries with the coil as shown. The coil becomes de-energized as soon as the interrupter trips. Normally two NO contacts of the... 

Keep the control circuits energized if possible, to further save on calculations and to obtain more accurate results. In the sample calculations as shown in Table I4.4 we consider this in a de-energized condition for the sake of more clarity. 

If the eomputer has been de-energized, elose the eomputer breaker, start the eomputer, and enter time of day. Under normal eonditions, the eomputer is left running eontinuously. 

Ignition time function (to de-energize ignition at the proper time). 

Figure 14-5. The light shows that the solenoid is de-energized, not that the oxygen flow has stopped.

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

Aberraute, /. = Eberraute. aberregen, v.t. deactivate, de-energize, tberwitzig, a. crazy, foolish. 

In the case of an interrupted pilot, de-energize the safety shut-off valves. 

A low-pressure switch can also be used in conjunction with a thermostat and a solenoid valve in the pump-down circuit. In this method of control, the thermostat does not stop the compressor but de-energizes the liquid line solenoid valve to stop the supply of refrigerant to the evaporator. The compressor continues to run and pumps down the evaporator until stopped by the low-pressure switch. When the thermostat again calls for cooling, it opens the solenoid valve, liquid enters the evaporator and the low-pressure switch will close again to restart the compressor. This method is used to ensure that the evaporator is kept clear of liquid when the plant is off. If there is any leak at the solenoid valve, it will cause the... 

Solenoid valves are used in refrigeration and air-conditioning systems for refrigerant lines, oil pressure pipes (to control oil return and capacity reducers), and water and compressed air lines. Four-port changeover valves (Figure 9Ab) are used to reverse flow in defrosting and heat pump circuits. A de-energized expansion valve will act as a solenoid valve. 

Most electric motor actuators are equipped with limit switches, torque limiters, or both. Limit switches de-energize the electric motor when the valve has reached a specific position. Torque... 

The presence of additional product channels can also be considered. In this analysis M represents any collision partner ([M] = P/RT), the parameters and kj are the rate coefficients for energization and de-energization of A as a consequence of intermolecular collisions, and fi represents the efficiency of collisional energy transfer given by (Gardiner and Troe, 1984)... 

If a sprinkler system is installed in a computer room or similar area, provisions must be made to automatically de-energize all electrical power to the room and equipment, except power to lighting, in the event of sprinkler operation. Ensure that de-energizing activity leads to a fail-safe condition. Preferably, this should take place prior to water application to minimize damage to exposed electronic circuits. This can be accomplished automatically by smoke detection systems. Manual activation is tolerable for constantly attended locations. Where automatic sprinklers are installed in areas containing minimal combustibles as described above, a sprinkler density of 0.10 gpm/ft (0.38 Ipm/m ) should be provided. Refer to NPEA 75. 

De-energize The ESP is de-energized through automatic controls when the following process situations exist ... 

SIS trip The ESP is de-energized when the SIS trips and pulls feed. Start-up Start-up conditions represent a risk for upset conditions. The ESP is typically not commissioned until after the unit has reached steady-state. 

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