Test Instruments 2008

  1. What is it called when auto-ranging is used with a digital meter and a voltage is displayed before coming into contact with the circuit? PP17

    How can this be eliminated in most meters?
    ghost voltage

    By selecting the manual setting
  2. What are the accuracy ranges of analog and digital testing meters for voltage? PP18
    • analog= 1-5%
    • digital= .01-1.5%
  3. Whenever possible, the test leads of a meter should be connected to which side of a fuse or breaker and why? PP20
    load side, to provide better short circuit protection
  4. What should always be worn with rubber insulating gloves? pp22

    Rubber gloves should always be laboratory tested at what interval? pp22
    leather protectors (gloves)

    every 6 months at minimum
  5. the primary contributing factor to arc blasts is what and is caused by what? PP25 test instruments NJATC 2008
    transient over voltages, caused by high current loads being switched off, or by lighting strikes nearby.
  6. There are 4 IEC1010 measurement categories, from low to high voltage, what are they and what system types do they apply to? PP26 test instruments NJATC 2008
    phase 4 is closest to the utility
    • Cat I: electronic; any high-voltage, low energy source derived from a high-winding-resistance transformer, such as the high-voltage section of a copier
    • Cat II: 1 phase receptacle connected loads
    • Cat III: 3 phase distribution, including 1 phase commercial lighting
    • Cat IV: 3 phase at utility connections, or any outdoor conductors
  7. With an IEC 1010 measurement category of Cat II (1 phase receptacle connected loads), outlets at more than how many feet from a Cat III source and Cat IV source become Cat II? PP26 test instruments NJATC 2008
    outlets at more than 30' from Cat III or 60' from a Cat IV source become Cat II
  8. Grounding in electrical construction is accomplished by connecting the circuit to what? PP30 test instruments NJATC 2008
    • metal underground pipe
    • metal frame of a building
    • concrete encased electrode (Ufor)
    • ground ring
  9. How do you test the leads on a DMM and what are the desired results? PP37 test instruments NJATC 2008
    The DMM must first be zeroed and then the leads should be touched together for an ohmic reading of less than 1
  10. What is magnetic field coupling also refered to as? PP18 test instruments NJATC 2008
    Noise.   this is because it is mutual iduction between 2 signal wires.
  11. A temperature difference in any enclosure, or metalic part of an electrical system is considered a light load, heavy load, and a maintance issue at how many degrees F? PP40
    • Light load= 40F
    • Heavy load = 60F
    • Routine maintanence
    • required = 85F
  12. If a test instrument has a red and green condition indication rather than black (common) and red (hot) then this is considered what? PP41
    • Red = high voltage
    • Green = low voltage
  13. In what order should leads on a DMM always be applied to an energized circuit and why? PP 42
    • Black (common) applied 1st
    • Red (hot) applied 2nd
    • Because Red first can cause an energized circuit with the electrician in series with the ground by holding the black lead
  14. Discharge on a test instrument is represented by what symbol? PP 42
    The diode symbol
  15. The formula for Peak, Effective, Average, and Peak to Peak voltages in an AC sine wave are? PP44
    • Peak = 1.414(RMS/eff) a.k.a. max instantaneous value
    • Effective (RMS) = .707(peak)
    • Average = .637(peak)
    • Peak to Peak = 2(peak)
  16. The true RMS test instrument is best suited for measuring with what equipment? PP44
    • Solid State components
    • variable frequency drives (VFD)
    • programmable logic controller (PLC)
  17. The neon test light is the most common type and must not be used to test what? Why? PP44
    A GGCI, becuase it does not draw enough current to trip the GFCI, since the resistance is so high.
  18. A voltage indicator (inductive tester or tic tracer) will not indicate a voltage if the cable is what? PP48
Card Set
Test Instruments 2008
test instruments NJATC 2008