1	Basic Electricity A.U.C.S.C Instructor - Tim Jenkins
2	Basic Electricity- Corrosion Corrosion is a electrochemical process. Electrical instruments are used in some corrosion testing and we need to understand various electrical terms, laws and circuits when working with cathodic protection. For this class we are going to cover the electrical portion.
3	Basic Electric Electric components Conventional current flow DC Char. waveform AC Char. waveform Rectifiers Components Principle Ohm’s law Kirchhoff’s voltage law Kirchhoff’s current law Circuits Parallel Series Measurements
4	Basic Electric Imagine if you will, you want a cup of water and went to a nearby faucet. You turn the knob clockwise and water begins to pour out. You just a simulated a electrical circuit and current flow. How?? The water is your current (electrons). The knob is your switch. The water line is your circuit. When you turn on the water, you switch the current on to allow the current to flow, the current will flow because of the potential difference, on the one side of the valve of the faucet there is no pressure and the other side you have water pressure, this makes up the Voltage or EMF. The resistance is the size of water lines and the openings on the valve and the opening on the end of the faucet, this will decide how much water will flow in a given time. The smaller the opening the more resistance to the water flow. In a electrical circuit, the smaller the wire the more the resistance on current flow; the wire and components will decide how much current will flow in a given time better known as amperes.
5	Basic Electric - Voltage Voltage - Known as Volts or EMF (electromotive force), it is a measurement of the potential difference or amount of force to move the current in a circuit. 1.000 volts = 1000 millivolts .100 volts = 100 millivolts .010 volts = 10 millivolts .001 volts = 1 millivolt .000001 volts = 1 microvolt
6	Basic Electric - Current Flow Current - is the flow of electrons through a conductor or a conducting path and is measured in amperes. Ampere is the common unit of current of a flow rate of a charge of 1 coulomb per second. One Coulomb is the unit of charge carried by 6.24x10 to the 18th power of electron charges or 6.28 billion billion electrons. 1.000 ampere = 1000 milliamperes .100 ampere = 100 milliamperes .010 ampere = 10 milliamperes .001 ampere = 1 milliampere .000001 ampere = 1 microampere
7	Basic Electric - Resistance Resistance - is the restriction or blockage of current flow. Resistance is measured in Ohm’s. The typical symbols of resistance is “R” or “W” (Greek letter omega). Resistance may also be measured in milliohms (0.001 ohms) or in megohms (1,000,000 ohms).
8	Basic Electric - Insulation Insulation is a form of resistance to current flow. The material with high resistance makes a good insulator. Insulators are used in cathodic protection to block current flow or to set up barriers to keep current flow onto pipelines. Coatings is a form of a insulator barrier to block any discharge of current off the pipe lines to the surrounding environment. Weld-in’s, couplings, unions, bolted couplings
9
10
11
12
13
14
15
16
17
18	Basic Electric - Conductivity Is the opposite of resistivity. The ability to conduct a flow of current Measured in mho’s Different materials have different values of conductance. Current conducting capability based on Copper being 100% Copper - 100% Aluminum - 60 Magnesium - 36.8 Zinc - 27.6 Brass - 24.6 Steel - 9.6 Lead - 8.0
19	Basic Electric - Impedance Impedance is the total opposition that a circuit presents to alternating current, similar to resistance in a direct current circuit. Impedance is measured in ohms, as is DC resistance.
20	Basic Electric - Power Power is the energy used by an electrical device. Power is measured in Watts or Wattage.
21	Basic Electric - Components Schematic Symbols
22	Basic Electric - DC
23	Basic Electric - AC
24	Basic Electric - Rectifying AC
25
26	Basic Electric - Diodes
27
28	Basic Electric Checking the Diode Module
29	Basic Electric Diode Module Check Four Part Test
30
31	Basic Electric - Transformer
32	Basic Electrical Efficiency Rating Calculation
33	Basic Electric - Resistors
34	Electrical Measurements Digital multimeters are used in most electrical measurement application. Measurement of voltage drop - Place meter in parallel over load. Measurement of current drop - Place meter in series of the circuit. Circuit must be open in order to achieve this unless using a special meter such as the clamp on meter or if you are using a shunt resister. Shunt resister has different ratio to indicate amount of current based on voltage drop across the shunt, for example, 50mV = 1 Amp. A reading of 100 mV would equal to 2 amps of current.
35	Basic Electric - Polarity Determines the direction of conventional current flow Determines which metal is more noble. Determines which is the Cathode and which is the Anode. Instrument such as digital or analog meter will help in determine the polarity.
36	Conventional Current Flow
37
38	Basic Electric - Rectified systems
39
40
41
42
43
44	Ohm’s Law E = I • R I = E / R R = E / I E = Voltage I = Current R = Resistance Power (Watts) P = E • I P = I² • R P = Power in watts R = Resistance in ohms E = Voltage in volts I = Current in amperes
45	Basic Electric - Kirchhoff’s Law Voltage Law - The sum of the source voltage around any closed loop of a circuit is equal to the sum of the voltage drops across the resistances in the loop. (Parallel Circuit)
46	Basic Electric - Kirchoff’s Laws Current Law - The law states that as much current flows away from a point as flows toward it. (Series Circuit)
47	Basic Electric - Series Circuit The current is the same everywhere. IT = I1 = I2 = I3 = I4 The voltage drops may all be different depending on the values of each resistance, but the sum of the voltage drops (ET) must add up to the voltage of the source (an example of kirchoffs Voltage Law). ET = E1 + E2 + E3 + E4 The total resistance (RT) of a series circuit equals the sum of the individual resistance. RT = R1 + R2 + R3 + R4
48	Basic Electric - Parallel Circuits Voltage drop across each branch is the same and is equal to source voltage. ET = E1 = E2 = E3 Total current flowing into and out of the junction point of the branches equals the sum of branch currents (Kirchhoff’s Current Law). Total (equivalent) resistance is equal to the reciprocal of the sum of the reciprocals of the individual resistances. RT = R1 • R2 Resistance total for resistors or loads in a parallel circuit. RT = The total (equivalent) resistance is always less than the smallest resistance in the circuit.
49
50
51
52
53