Question 2.24: Electric Shock Consider the unfortunate bald utility worker ...
Electric Shock
Consider the unfortunate bald utility worker of Example 2.13 who climbs an aluminum ladder with bare feet and comes into contact with an overhead power line bearing 30 cos(100 πt) Kv (Figure 2.86). The worker’s body resistance is 315 kΩ. This situation can be modeled as a resistor (his body) connected between the terminals of a power supply (the wire) (Figure 2.85). How much current flows through his body? If the minimum current needed for a shock to be fatal is 100 mA, does the worker survive?
First, given the voltage source of 30 cos(100 πt) kV, we need to determine of the frequency of the voltage. The voltage source function is V_S = V cos ( ωt ), and the frequency, f, is defined as f = ω/2π. This clearly shows that: ω = 100π, and the frequency of the circuit is: f = 100π/2π or f = 50 Hz.
PSpice Schematic Setup:
- Instead of using the Direct Current Voltage Source, a sinusoidal voltage source has been chosen. The sinusoidal voltage source for PSpice can be obtained by typing “VSIN” in the “Place Part” window; its amplitude and frequency are set as shown in Figure 2.86.
- Follow the steps in the Tutorial section to set up a Time Domain Analysis Simulation. The current plot across the human body is shown in Figure 2.87.
- Figure 2.87 shows the maximum (also known as amplitude) of the current is less than 100 mA. Therefore, the worker is able to survive the electric shock.
