Arcing time

As the arcing time is very lows it causes no or onlv a small amount of contact erosion. 

Figure 6.156 Copper electrode burn-off versus arcing time t for short-circuit currents in the range 0.8kA. ..15kA rms.

For copper, the electrode burn-off versus arcing time has been measured for different short-circuit currents up to 15 kA (root mean square value), see Fig. 6.156. 

FIGURE 8.5 Fonnation of polyynes by arcing graphite at 10 A in different volumes of methanol. Growth of the band at 250 nm as a function of arcing time. 

The kinetics of polyynes production with the submerged carbon arc appears linear with the arcing time and the amount of current or energy (power) supplied to the reaction system. 

Prolonged arcing seems to be an attractive route for the preparation of bulk quantities of polyynes in solution. In Chapter 8 we have shown that polyynes accumulate linearly with arcing time into organic solvents. The best solvents for rapid polyyne formation appear to be hydrocarbons rather than alcohols, but the latter offer the advantage of forming a very low level of polycyclic aromatic hydrocarbons (PAHs) as secondary products. 

Where t is the melting time plus the arcing time and I is the current flowing in the fnse. 

It should be noted that when the melting time exceeds about 0.1 sec the corresponding arcing time is less than 0.01 sec. Therefore for times above 0.1 sec it may be assumed that the melting or pre-arcing time is in fact the clearance time. The fuse manufacturers normally give curves for the... 

Where, t, is the melting time period. tc is the clearing time period. tc — tm is the arcing time period. 

Adjustment of pH would be by use of mineral acids or alkalis. This sometimes has the added advantage of precipitating unwanted dissolved sails. However, there arc times when salts are dissolved by the pH change. This would be a disadvantage if the purpose of the treatment is to remove these substances, when dissolving them would make it nit)re difficult. 

By Its very nature, the simple batch reactor operates in an unsteady state the reactant (and product) concentration arc time-dependent. 

An arcing phase, where the main-stroke is established, the arcing time t being less than 1 ns this final stage, a very destructive one if the current is not limited, has been by far the least studied. 

Famous examples of reaction databa.ses are CASREACT, Chemreact, and ChemInformRX, all online on STN. None of the reaction databases covers the whole chemical literature, and furthermore there arc time periods that are not included in any of the available databases. ... 

WELD PASS(ES) WELDING PROCESS FILLS CLASS NETAL DIAMETB a POLARITY JRRBfT (DC) AMPS VOLTS ARC TIME SEC TRAVEL SPEH) CMMMUTE HEATHHHIT MAX KJflHM... 

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