Fuse-free systems

Note It is. however, possible to eliminate the use of HRC fuses in LT systems at least, with Ihe availability of more advanced technology in an MCCB or an MPCB (motor protection circuit breakeri. See Section 12.1 I for a fuse-free system. 

While a fuse-free system is gradually gaining preference, for all ratings, as discussed later, it is recommended that a breaker (ACB or MCCB) be employed for large motors of at least 300 h.p. and above to ensure better protection for the motor. 

Purpose Unfavourable operating conditions Fault conditions Protection Single-device motor protection relays Summary of total motor protection Motor protection by thermistors Monitoring of a motor s actual operating conditions Switchgears for motor protection Selection of main components Fuse-free system... 

Ca2+ sensing by 1 can be understood by considering a PET process originating in the Ca2+-free tetracarboxylate receptor and the linearly fused tricyclic system. The rapidity of the process may be ascribed to the low oxidation potential of the electron rich alkoxyaniline donor and to the short distance of separation between the two transfer components. The minimal separation arranged by a virtual spacer of zero carbon atoms is worthy of note. A low level of luminescence is seen owing to the fast PET. 

Free-radical cyclizations using ethyl radicals generated by EtsB/air system or stannyl radicals systems provide a range of carbocyclic and heterocyclic hydroxylamines (equation 77). Stereoselectivity in these reactions is variable but can be semiquaUtatively predicted by Beckwith-Houk models . Depending on the substitution pattern of the emerging cyclic system, stereoselectivity can be very high, especially in fused polycyclic systems (equation... 

The last two assumptions are probably as valid for synthetic liquid fuels as for petroleum. The first assumption is partially satisfied by the separation steps which provide three fractions two of which (the monoaromatics and the di-+ triaromatics) are free of fused ring systems larger than three rings. The proton NMR analysis of the third fraction (the polyaromatics)—which contains four or more rings, condensed and noncondensed—is then only qualitative. 

Other cases are not always so obvious, yet any structural or steric feature which influences the close approach of the it bond and the free-radical center will influence file rate of cyclization and hence the yield of cyclized product. For example, trans-fused cyclopentyl systems are much higher in energy than cis-fused ones thus file trans-fused cyclopentyl compound does not cyclize effectively and gives only reduction,... 

Since Mills and Nixon studied in their original paper hydroxy derivates of fused aromatic systems like /3-hydroxyindan [1], we examined a series of model compounds possessing OH group attached at the /3-position [14], It was found that the hydroxy group exerted overwhelming influence on the electrophilic susceptibility of the aromatic carbons by substantial activation of its ortho positions. However, the free /3 position is the most active one because of the Mills-Nixon effect, which amplifies the OH inductive effect. Hence the selectivity in the electrophilic substitution reactions is governed once again by the MN effect [14]. 

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