Lightning transients

For selection of protection components and devices, the transient voltage withstand level of equipments and circuit components must be known or conservatively estimated. For most equipment and circuit components, standards do not exist for lightning transient levels. Therefore, information available from manufacturers must be obtained, laboratory testing performed or conservative engineering estimates used. Limits for common types of equipments and components are provided for guidance. 

The primary advantages of mechanical scales are that they are relatively inexpensive in smaller capacities they do not need electrical power, enhancing thein portabiUty and they do not need to be protected from power line transients or lightning strikes. 

A.m blent Environment. The environment around the flow conduit must be considered in meter selection. Such factors as the ambient temperature and humidity, the pipe shock and vibration levels, the avadabiHty of electric power, and the corrosive and explosive characteristics of the environment may all influence flow meter selection. Special factors such as possible accidental flooding, the need for hosedown or steam cleaning, and the possibiHty of lightning or power transients may also need to be evaluated. 

I-3.6.2 Electronic control, monitoring, and hydrogen gas measurement equipment shall be properly grounded and isolated from piping to help prevent overpressure/ accidental shutoff situations caused by equipment failure due to lightning strikes and electrical transients and to prevent safety hazards caused by fault currents. Electrical isolation equipment for corrosion control purposes should not be installed in buildings unless specifically designed to be used in combustible atmospheres. 

The first visual experience was a series of transient palings of color all over the room, which began at 10 15. Periodically there seemed to be flashes of white lightning. In between, everything seemed very distinct and very beautiful. 

The earlier pre-1970 VDRs were based on SiC and had a values up to about 5. These are still used to some extent where large amounts of energy are to be dissipated, as in lightning arresters. In general VDRs are based on ZnO and have a values up to about 70, but more commonly in the range 25-45. They are widely used to protect circuits against transients. 

Odenberg, R., Protecting facilities from induced lightning and power line switching transients, FAA-RD-77-84,... 

A further important and yet incompletely resolved matter is the nature of the heating event in which chondrules formed. The experimental study of Cohen et al. (2004) shows that chondrules probably formed in a matter of minutes to hours. This implies a flash heating process (Boss, 1998), such as might be caused by shock-heating or lightning strikes in the solar nebula. If this is the case then chondrule melting temperatures represent transient temperatures rather than the ambient temperature of the solar nebula. 

Indirect effects of lightning can cause power transients and anomalies that can damage sensitive/criti-cal LRUs or damage wire looms. EMI can be induced into wiring by the lightning currents flowing on the outside of the fuselage. 

Both Ps and Pa can be estimated from an analysis of historical accident data. The principal challenge is in developing a statistical approach for estimating Pe as a function of lightning-strike intensity, induced transient levels, and equipment sensitivity. In addition, the Pe values for several equipment types must be considered when determining a system failure probability. 

The resistive heating can conduct to an increase of the temperature until values at which the yield strength admissible for steel is very low. The thermal effect of lightning strikes on objects can be simulated by transient heat conduction in soHds. 

The 3-D transient temperature distribution in metals struck by different lightning currents is determined using a computer program based on the volume technique, developed in MetwaUy et al. 2003. The temperature field within the material 0(r, z, i) is obtained upon solving the energy equation subjected to the appropriate boimdary and initial conditions. The results are presented in MetwaUy et al. 2003. 

Transient luminous event (TLE) Tsible optical events in the upper atmosphere associated with terrestrial lightning includes red sprites, blue jets, elves, halos, and others. 

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