Nace CP 1 - Page 53

Basic Electricity 1:30
CP 1 – Cathodic Protection Tester Course Manual
© NACE International, 2000
02/01/05
Record the data collected on the Exercise 1.1 Data Sheet
provided.
Step 1. Using the voltmeter, measure the voltage of the battery. Does
it equal the printed battery voltage? If not, why?
Step 2. Using the ohmmeter, measure the resistance of each
resistor. Do the resistances equal those marked on the
resistors? If not, why?
Step 3. Calculate the total resistance (R
T
).
Step 4. Wire the 1000  (R
2
), 100  (R
3
), and 10  (R
4
) resistors
below the battery in series and measure the total resistance
(R
T
) with the ohmmeter. [DO NOT CONNECT
BATTERY] Does your measurement equal your
calculation? If not, why?
Step5. Using Ohm’s Law and your measured values of E
T
and R
T
,
calculate total current (I
T
).
Step 6. With resistors still connected in series, connect the battery
and the ammeter in series. [CAUTION: Make certain that
the meter is set to mA scale before connecting battery.]
Measure the total current (I
T
). How does it compare with
your calculated value?
Step 7. [SET METER TO VOLTS
DC
]Measure the IR drop across
each resistor and add them up and measure the source
voltage. Does this sum equal the total measured voltage?
DIODE CHECK
Check the diode with the diode checking circuit. Is it functioning
properly?