Protective devices availability

The protection of the remaining system is a matter of system design and appropriate application of the protective devices available depending upon system requirements. These three items have been taken out of the scheme of Figure 13.21 and redrawn in Figure 16.14 for more clarity. 

Chapter 11 discussed the dangers of falls. There is a variety of fall protection devices available. Rgure 28-5 provides some examples. Most fall PPE interrapts falls in progress. Because they must interrupt a body in motion, the devices must withstand certain loads prescribed by standards. 

Circuit Protective Devices. There are various types of short-circuit protective devices available for electrical circuits and equipment rated 600 V or less. 

Nickel carbonyl should be used in totally enclosed systems or under good local exhaust. Plants and laboratories where nickel carbonyl is used should make use of air-monitoring devices, alarms should be present in case of accidental leakage, and appropriate personal respiratory protective devices should be readily available for emergency uses. Monitoring of urinary nickel levels is useful to help determine the severity of exposure and identify appropriate treatment measures. Some large-scale users of nickel carbonyl maintain a supply of sodium diethyldithiocarbamate, or Antabuse, a therapeutic agent, on hand for use in case of overexposure. 

A separate single-phasing protection device is available in two versions ... 

Examples are HRC fuses (both LT and HT) and MCCBs and MCBs (LT only), which are available with current limiting features and are in extensive use. The tripping time of these devices is extremely low and much less than one half of a cycle of the current wave. They therefore do not allow the fatilt ctirrent to rise to its prospective peak. The protected devices and components can thus be selected based on the let-out energy of such devices on fault, which is extremely low, than the fault level of the system. If... 

Referring to the data available from experiments, as shi)wn in Table 23.1, it hits been estimated that a Vp, of I. Hj should be sufficient to account for the harmonic effects. For this dielectric strength is designed a capacitor unit and selected a switching or protective device. 

The electrical distribution system design and equipment selection must consider requirements of the utility company for protection and metering. Available short circuit currents from the utility distribution network to the primary of the facility s main transfoiTner must be considered in selecting circuit protection devices for the facility distribution system. 

The analysis and understanding of the operation of protection systems and the application of protective devices to power systems is wide ranging and complex. This section considers only the objectives of protection systems, discrimination and its importance to protection, and describes the most common types of relay used in industrial power systems. Many publications covering the subject of protection systems are available (e.g. Power System Protection, edited by the Electricity Council). 

However, other type of protective devices are available which can be used. They are ... 

Various cyber protection devices are currently available for use in protecting utility computer systems. These protection devices include anti-virus and pest eradication software, firewalls, and network intrusion hardware/software. These products are discussed in this section. 

When significant quantities of residue are associated with the protective device (i.e. cover, spacer, paper or gauze), it is not possible to determine whether the material was available for absorption, that is, was in contact with the skin. If the study is otherwise well-conducted and reported, one approach is to assume that this residue was not available for absorption, and recalculate the applied dose accordingly. 

Various attachments and plant protection devices can be added to cultivators (see the reference Steel in the Field, produced by the USDA Sustainable Agriculture and Research Education [SAKE] Sustainable Agriculture Network, available from Iowa State University). 

Face shields are protective devices intended to shield the wearer s face, or portions thereof, in addition to the eyes. The face shield would be used when handling pesticides where it is highly likely that splashing will occur. Face shields are available with or without removable windows. Figures 6.1, 6.2, and 6.3 show handlers wearing face shields. 

Personnel protection devices must be used to protect the ear in an industrial plant. These are earplugs made of rubber or plastic that fit snugly in the ear canal without discomfort and effectively protect the ear. They are also available as a foam cylinder that can be compressed and twisted to be inserted into the ear canal. There are helmets available that have noise attenuating electronic components and communication features. In selecting these helmets, safety engineers must exercise caution and must take steps to ensure that the devices are properly selected and used by the workers without distraction and annoyance. 

This review summarizes the available morphological evidence for coronary microembolization in patients who died from coronary artery disease, most notably from sudden death. Then the experimental pathophysiology of coronary microembolization in animal models of acute coronary syndromes is detailed. Finally, the review presents the available clinical evidence for coronary microembolization in patients, highlights its key features - arrhythmias, contractile dysfunction, microinfarcts and reduced coronary reserve -, compares these features to those of the experimental model and addresses its prevention by mechanical protection devices and glycoprotein Ilb/IIIa antagonism. 

Considerable variety is available in the types, styles, and applications of eye and face protection. For the conditions which exist in most chemical storage facilities, where packaging remains sealed, eye protection will be dictated by the presence of physical hazards. Many warehouse operators require safety spectacles in warehouse and maintenance areas. Persons who wear prescription lenses should wear protective eyewear fitted with prescription lenses or protective devices worn over prescription eyewear. 

Moulded case circuit breakers are also available for incoming and busbar section purposes, with ratings up to 6000 A and service voltages between 220 V and 660 V. (At 415 V a 4000 A circuit breaker would satisfy the duty of a 2500 kVA feeder transformer with about 15% spare capacity.) These are also available as 4-pole units. Circuit breakers having ratings of 800 A and above are often provided with several adjustments that widely modify the shape of the complete protection curve, as described in Chapter 12. This enables the curve to coordinate with almost any other protective device or equipment that is immediately upstream or downstream of the circuit breaker. Some circuit breakers with the higher rated currents are also provided with integral earth fault protection facilities. 

Protective devices are often used to prevent contact of chemicals with the respiratory tract, eyes, skin, and digestive system. Foulger states that a safety program should be designed to prevent or minimize contact of chemicals (or materials that are injurious to health) with the body respiratory protective devices, safety glasses and shields, impermeable clothing, gloves, shoes, and masks must be made available... 

The RCS has enough capacity to relieve the overpressure, but the setpoints or the availability of relief valves during shutdown is the issue. One plant implemented a diverse pressure relief path and cold overpressure protection device that maintains pressure within safety limits during all shutdown modes. 

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