Author: Kaitlyn Beardshear Page 4 of 5

So much of this week has me running around doing a million things. This week started off with building storage shelves. The task sounded easy enough at first, but then all of the metal bars were bent, the wood didn’t fit in place, there weren’t enough brackets so we had to make more. By the time we finally finished it was the end of the day. The rest of the week has consisted of pulling items off the sub and unraveling the wires. The wires were so much effort to try and pull them through tiny spaces. And of course right where you can just barely get to it is a zip tie you need to cut. One of the biggest things I did this week was helping with the penetrator removal. The penetrators allow for wires to pass from outside the sphere to the inside while maintaining a seal. They are very important and need to be handled carefully. After they are pulled out, I would take them, fill out a certified tag identifying the object and it’s serial number, after inspection they would be packed up. This week has been busy but I’m glad to be back at work.

Great news, I finally went back to work! After 36 days of staying at home and reading I was itching to be working with my hands again. We’ve started dismantling Alvin. This week, the ET’s pulled off implodable volumes, which is anything that has air inside of it and has the potential to collapse with depth. These items are important; they are tracked by serial number and each one has a thick stack of paperwork to certify the depth they can go to. If one were to implode, there would be a pressure wave radiating outward that could damage the sub. Before we take anything off the sub, we have to find its location. Everything needs to be verified to check the weight balance of the sub. In the middle of the sphere is an x, y, z origin point; we measure from an item’s center of gravity to find its location. Once we have a location, I would take the item and measure the air and water weight. With those two measurements, the item’s volume can be calculated. After that everything gets cleaned up and put away. Throughout all of this, I’m recording all of the measurements and reporting them. It was busy work but it felt so good to be doing.

This week I’ve been learning about how the Navy created standards for their equipment and kept calibration records. In 1973, the Electronic Test Equipment Classification Board was created in order to control what instruments were used and to eliminate unnecessary electronics. Equipment fits into two categories: general use, meaning the instrument can be used for multiple systems, and special use, which are used on only one system. With all the equipment being used, there needed to be a system to track what instruments are where and when they need to be calibrated. To do this, the Ship Configuration and Logistic Support Information System was created. In addition to tracking instruments, it also helps in listing documentation related to each instrument, training required to operate, and calibration schedules. Calibration is important so that the operator knows that the instrument is functioning correctly. When an instrument is calibrated, it is compared to a known standard. If what the instrument measures is outside of the allowed tolerance, it needs to be adjusted. Once an instrument is calibrated, it is important to ensure that it stays within limits. If a piece of equipment is exposed to heat, moisture, or dropped it may need to be recalibrated. 

In continuing my reading of the NEETS modules, this week I learned more about alternating current. While direct current only flows in one direction, alternating current regularly switches directions. An AC circuit can be made by spinning a conductor, such as a loop of wire, in a magnetic field. This forms a generator. One way to determine the direction of current flow is to use the left hand rule: when holding your hand as shown in the example (taken from the NEETS module), your thumb will point in the direction of rotational motion, the index finger shows the direction of magnetic flux (movement from north to south), and the middle finger points in the direction of current flow. An easy way to remember the left hand rule is My Fine Clothes- Movement (thumb), Flux (index finger), Current (middle finger).

This week I finished the NEETS module on direct current. One thing that I learned is that there are multiple formulas that can be used to calculate resistance in a parallel circuit. The first formula being Ohm’s Law (resistance is equal to voltage divided by current, R=V/I). This works to find the resistance, but if there is more than resistor one then you’ll need to find equivalent resistance instead. The reciprocal of equivalent resistance is equal to the addition of the resistor reciprocals (1/R_EQ = 1/R₁ + 1/R₂ + 1/R₃ +…+ 1/R_n ). Another option if the circuit contains resistors that have the same value, you can calculate resistance by dividing the ohmic value of one of the resistors by the number of resistors (R_EQ = R/N). This is simple but only works when the resistors are equal. 

Another thing I finally understand despite years and multiple explanations from previous professors (sorry Dr Moore), is voltage dividers. A voltage divider is used to provide different voltage levels to a circuit while only using one power source. A voltage divider consists of multiple resistors connected in series that step down the voltage. The way to calculate the value of the resistors needed is to use the 10% rule: the current used in the divider resistor should be approximately 10% of the load current. This is called the bleeder current and is not used in the circuit. Once the divider resistor is calculated, finding the total current and dividing by the voltage will give the ohmic value of the second resistor. 

This week I have been continuing to read from the Navy Electricity and Electronics Training Series (NEETS). This week I finished the chapter on batteries in which I learned about the parts of a cell, the different types of cells, and cells can be combined to form different types of batteries. I also started the chapter on direct current. So far I have read about Ohm’s Law, ways to calculate power and efficiency. Hopefully I’ll finish reading the module this week and move onto the next one.

At this point, the Alvin team is on stand down for a few weeks. During this time, I’ll be doing some research and learning while sheltering in place. For my blog posts, instead of reviewing what I did the past week, I will be writing about what I am reading. 

The first thing I am reading from is the Navy Electricity and Electronics Training Series (NEETS). It consists of 24 modules that cover subjects ranging from electrons to fiber optics. After each section, there are quizzes and at the end of each module is a test. 

The first module is Matter, Energy, and Direct Current. It starts out with atoms and the subatomic particles, to what is magnetism and how it relates to electricity, before going into voltage, current, and resistance.