Question

5) A parallel series electric blasting circuit consists of 6 branches of 8 caps each. Cap legwire length is 28 ft. The cap circuit is connected by 50 ft total length of No. 16 gauge bus wire. The lead wires are No. 14 gauge 1,000 ft long one-way. Find the minimum dc current and voltage required to safely fire this blast under current leakage conditions.

Answer 1

Answer:

Minimum DC current $= 9$ Ampere

Voltage $= 74.862$ V

Explanation:

Here in this questions three resistors are used in series

Resistance of cap circuit

$R_1 =\frac{ 8* 2.3}{6} \\R_1 = 3.067$

Here $2.3$ is the resistance per cap

Resistance of bus wire

$R_2 = \frac{50 * 4.02 }{1000} \\R_2 = 0.201$

Where $4.02$ is the resistance per $1000$ feet of bus wire of gauge 16

Resistance of firing line

$R_3 = \frac{(2*1000)* 2.525}{1000} \\R_3 = 5.05$

where $2.525$ is the resistance per $1000$ feet of bus wire of gauge 14

Total resistance is equal to

$R = R_1 + R_2 + R_3\\R = 3.067 + 0.201 + 5.05 \\R = 8.318$

Current in firing line is equal to

$1.5 * 6\\= 9$

Voltage is equal to product of resistance and current

$= 9 * 8.318\\= 74.862$