Power disconnect

When the dye front reaches the bottom of the gel, turn power supply off and disconnect power cables. 

The gravity powered insertion of the control rods is accomplished by disconnecting power to the holding brakes of the CRD motors. This disconnect is part of the PPIS and operates upon various reactor trip signals. Opening... 

CAUTION. Double-pole/neutral fusing. Disconnect power before servicing. 

CAUTION. This unit has two power cords. Remove both cords to disconnect power. 

Fuses and circuit breakers are examples used in electronic products to sense excessive current drain and disconnect power from a failed part. Fuses within circuits safeguard parts against voltage transients or excessive power dissipation and protect power supplies from shorted parts. Thermostats may be used... 

Always turn off and disconnect electrical equipment Irom the power mains before opening the equipment cabinet for servicing or cahbration procedures. Do not rely on switches to disconnect power, as sometimes they are defective, and sometimes the switch has been miswired or mislabeled such that the off position is actually the on position. 

If hot work inside the space is interrupted, special precautions should be implemented. Disconnect power to arc welding or cutting units and remove the electrode from the holder. Turn off torch valves and shut off the gas supply to gas welding or cutting units at a point outside. Remove the torch and hose from the space, if possible. Cylinders for welding operations should never be placed in confined spaces. 

Disconnect power and check for free movement of magnet and contact assembly. 

In the event of high radiation levels inside the building the "Area Monitor" interlock will disconnect power to the building vent and heater fans and drop the control rods. 

Disconnection b will not do as the nitio group is meta-directing and in any case nitro benzene wiU not react under FriedeTCrafts conditions. Disconnection a is fine as the MeO group is more powerfully ortho-direeting than the Me group (Ber., 1907, 3514). 

Cut-oul wind speed is the maximum w ind speed beyond which the prime mover may overspeed above its permissible limits. As the structure and the blades are designed for a particular maximum speed, a wind speed higher than this may exceed their mechanical endurance and become unsafe. At this speed the brakes apply and the machine is disconnected from the grid. The cut-in and cut-out speeds define the wind speed limits within which the turbine will work safely through the generator. Rated wind speed is the speed at which the prime mover rotates at the rated negative slip and generates the rated power. 

If the field excitation is also lost, the generator will run as an induction motor again driving the primer mover as above. As an induction motor, it will now operate at less than the synchronous speed and cause slip frequency current and slip losses in the rotor circuit, which may overheat the rotor and damage it, see also Section. 1.3 and equation (1.9). A reverse power relay under such a condition will disconnect the generator from the mains and protect the machine. 

As an energized capacitor retains its charge, even after a disconnection and causes a voltage transient on a reswitching, it is recommended that its circuit be closed only through a contactor or a breaker, with an undervoltage release. So that in the event of a power failure, the circuit will interrupt automatically... 

Ignition panel shall be furnished with a local power disconnect. 

It generally is recommended, and often required, that gas dcicciiuii systems be installed in a fail-safe manner. That is, if power is disconnected or otherwise interrupted, alarm and/or process equipment shutdown (or other corrective action) should occur. All specific systems should be carefully reviewed, however, to ensure that non-anticipated equipment shutdowns would not result in a more hazardous condition tlian the lack of shutdown of the equipment. If a more hazardous situation would occur with shutdown, only a warning should be provided. As an example, a more hazardous situation might occur if blowout preventers were automatically actuated during drilling operations upon detection of low levels of gas concentrations than if drilling personnel were only warned. 

Concentration levels where alarm and corrective action. should occur vary. If no levels are specified by the authority having jurisdiction, most recommend alarming (and/or actuating ventilation equipment) if combustible gas concentrations of 20 percent LEL (lower explosive limii ) or more are detected. Equipment shutdowns, the disconnecting of dccirical power, production shut-in, or other corrective actions usually are recommended if 60 percent LEL concentrations of combustible gas are detect... 

Some vertical drain lines in a building were no longer needed, so they were disconnected and capped but left connected to the horizontal main drain below. The caps were fixed with tape but were not made watertight as there was no way. it seemed, that water could get into them. Fifteen years later a choke developed in the main drain, water backed up into the disused legs and dripped into an electrical switch box. All power was lost, and some of the switch gear was damaged beyond repair [23]. 

The welders should have known that they should never enter a vessel until they or their foreman has checked that the vessel is isolated. by slip-plates or disconnection, and has accepted (and signed) an entry permit. Power supplies should have been disconnected, or if merely locked off, each person entering should have added his or her personal lock and kept the key. It is hard to believe that this was the first time normal good practice had not been followed. The management system was at fault. 

Indii iduals should immediately report any unsafe electrical conditions to prevent an accidental shock. Damaged or unauthorized extension cords must be taken out of service immediately. Indir iduals must shut off power at Uie breaker before disconnecting a damaged cord. To ensure Uiat someone else does... 

Indi% iduals must shut off power at the breaker before disconnecting a damaged cord. 

Relays have inputs from several current transformers (CTs) and the zone of protection is bounded by these CTs. While the CTs provide the ability to detect a fault inside the zone, circuit breakers (CBs) provide the ability to isolate the fault by disconnecting all of the power equipment within the zone. Thus, a zone bonndai y is usually defined by a CT and a CB. When the CT is part of the CB it becomes a natural zone boundaiy. When the CT is not an integral part of the CB, special attention must be paid to the fault detection and fault interruption logic. The CT still defines the zone of protection, but communication channels must be used to implement the tripping function. Figure 1 shows the zones of protection in a typical system. 

So that only the faulty equipment is isolated from the supply, the protective devices provided throughout a power system must discriminate between faulty and healthy equipment. This discrimination of protective equipment is a key element in the design of electrical systems and the selection of protection devices for use within them. Each electrical system must be provided with an adequate number of suitably rated disconnecting devices located correctly throughout the power system. These must be so arranged that only appropriate devices operate to remove the faulty equipment from the supply. 

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