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Exodus Advanced Communications

Electricity - Basic Navy Training Courses

Here is the "Electrician's Mate 3 - Navy Training Courses" (NAVPERS 10548) in its entirety (or will be eventually). It should provide one of the Internet's best resources for people seeking a basic electricity course - complete with examples worked out. See copyright. See Table of Contents.

- U.S. Government Printing Office; 1949



1. Complete the following statements:
   (a) The size of a Navy searchlight depends on the diameter of the __________.
   (b) The 36-inch and 24-inch light have a  __________ source of light.
   (c) The 12-inch light has an  __________ light source.
   (d) 36-inch searchlights are used primarily for  __________.
   (e) 24-inch searchlights are used primarily for  __________.
   (f) 36-inch light have  __________ for elevation and train.
   (g) A navy searchlight must:
          1. Have a beam free of  __________.
          2. Have a beam of  __________ color.
   (h) Most Navy searchlights can:
          1. train through  __________ degrees.
          2. elevate up to  __________ degrees.
          3. depress down to  __________ degrees.

2. Complete the following statements:
   (a) To start a carbon arc the carbon electrodes must first  __________.
   (b) As the arc electrodes are drawn apart current is conducted across the
        gap by carbon  __________.
   (c) The crater is a depression in the positive carbon in which the carbon
         __________ concentrates.
   (d) The crater must be positioned at the  __________ of the searchlight reflector.

3. What is the difference between high intensity and low intensity arcs?

4. Why must high intensity arcs be ventilated at all times?

5. How is power brought into the light to permit rotation of searchlights in train?

6. Complete the following statements:
   (a) Navy searchlights consist of:
           1. A  __________ to house the light source and reflector.
           2.  __________ to support the drum so it can be elevated.
           3. A  __________ to support the trunnion arms so they can be rotated to train
               the light.
   (b) The searchlight drum has:
           1. A  __________ for the main body.
           2. Access  __________ to get at the lamp and reflector.
           3.  __________ motor to prevent overheating of the lamp.
           4. Arc  __________ screen to indicate condition of the arc.
   (c) The arc lamp consists of:
           1. A  __________ to support the carbon feed mechanism.
           2. A  __________ to support, rotate, and feed the positive carbon.
           3. A metal  __________ or obduratior to keep the heat of the arc from the
               positive head.
   (d) The arc lamp has automatic mechanisms for
           1. Forced draft  __________.
           2. Positive carbon  __________.
           3.  __________ of positive carbon.
           4. Negative carbon  __________.
           5. Starting the  __________.
   (e) The positive carbon is automatically fed forward to keep the luminous vapor of
          the arc at the  __________.
   (f) The positive carbon is automatically fed forward by a motor controlled by
         a  __________ switch exposed to heat from the arc.
   (g) The positive carbon must be continuously rotated to keep the arc crater  __________.
   (h) The positive carbon is constantly rotated by the  __________ motor.

7. Complete the following statements:
   (a) The reflector of a searchlight is a mirror of  __________ shape which collects the
         light from the arc and reflects it in a parallel beam.
   (b) Reflectors are made of:
           1. Optical glass coated with  __________.
           2. Metals such as  __________.
   (c) In cleaning reflectors always wipe from  __________  __________.

8. Complete the following statements:
   (a) Shutters are used to  __________ the light beam while the lamp is on.
   (b) The iris shutter is too  __________ for signaling.
   (c) The vane type shutter is used for signaling because of its  __________.

9. Complete the following statements:
   (a) In a current control negative feed, the feeding of the negative carbon is controlled
        by balancing the pull of a solenoid, energized by the  __________ current, against
        the tension of a spring.
   (b) In a current control negative feed, when the solenoid pull and spring tension
         balance, the negative carbon ______ feeding.
   (c) In a current control negative feed system, increasing spring tension
        will  __________ arc length.

10. Complete the following statements:
   (a) In a voltage control negative feed, the feeding of the negative carbon is controlled
        by balancing the pull of a solenoid energized by voltage drop across the  __________,
        against a spring tension.
   (b) In a voltage control negative feed, when the solenoid pull and spring tension balance,
        the negative carbon  __________ feeding.
   (c) In a current control negative feed system, increasing spring tension
        will  __________ arc length.

11. Complete the following statements:
   (a) To keep the positive crater from burning off on one side adjust the  __________
         between negative carbon and positive carbon.
   (b) When carbon brush pressure is properly adjusted it takes a pull of  __________
        ounces to slip the carbons out of the head with feed rollers raised.
   (c) Positive carbon projection must be adjusted to assure proper  __________.
   (d) Arc length is adjusted by changing spring tension of the  __________ carbon feed.
   (e) To adjust lamp focus, move the lamp mechanism toward or away from
         the  __________.

12. Complete the following statements:
   (a) Search light carbons will last:
           1. 24-inch,  __________ minutes.
           2. 36-inch, at 190 amperes,  __________ minutes.
   (b) After renewing carbons operate light for about  __________ minutes to form
        positive crater.
   (c) If reaming positive or negative noses while hot, never allow reamer to  __________,
        to prevent reamer sticking as metal cools.
   (d) To clean reflectors:
           1. Use mixture of 3 ounces  __________ to 1/2 pint  __________.
           2. Polish from  __________.
           3. In polishing never use motion.
   (e) In lubricating lights, never use grease or oil on negative or positive  __________.
13. Name the tests, inspections and cleaning to be given searchlights
   (a) daily
   (b) weekly






1. (a) reflector
    (b) carbon arc
    (c) incandescent light
    (d) fire control
    (e) signaling
    (f) remote control
    (g) 1. flicker
          2. bluish white
    (h) 1. 360
          2. 110
          3. 20 or 40

2. (a) contact
    (b) vapor
    (c) vapor
    (d) focus

3. High intensity have smaller diameter carbons and heavier currents

4. To prevent overheating

5. By slip rings and brushes or by flexible cables

6. (a) 1. drum
          2. trunnion arms
          3. base
    (b) 1. barrel
          2. doors
          3. ventilation
          4. image
    (c) 1. column
         2. positive head
         3. shield
    (d) 1. ventilation
          2. feed
          3. Rotation
          4. feed
          5. arc
    (e) focus
    (f) thermostatic
    (g) symmetrical
    (h) feed

7. (a) parabolic
    (b) 1. silver
          2. chromium
    (c) center out

8. (a) shut off
    (b) slow
    (c) speed

9. (a) arc
    (b) stops
    (c) decrease

10. (a) arc
      (b) increase

11. (a) angle
      (b) 8 to 10
      (c) focus
      (d) negative
      (e) reflector

12. (a) 1.  105
            2.  45
      (b) 3
      (c) stop
      (d) 1. chalk, alcohol
            2. center out
            3. rotary
      (e) heads

13. See lists in chapter 15
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