[SYSTEMS] The basics of electricity and You

[Hicks]

The basics of electricity and You

 

A fairly standard looking control panel.

 

Basic interaction with electricity

A combat engineer will generally come across a variety of voltages when working on electrical equipment during his career and it is a common misconception that all of them are dangerous. In fact, electricity is not dangerous so long as you are responsible while working with it. Typically, an engineer will work with the following voltages: 

• Control circuit voltage (typically 12Vdc or 24Vdc). This voltage is found within control circuits and control panels, though the panel will still usually have a 110V or 230V supply which will be transformed down into the more usable 12/24V. This lower voltage is used as it is safer to work on and less likely to damage the sensitive components found within a control circuit. Example control circuits include keypads, control units for machinery such as elevators or cargo shuttles, and door panel control units
• Standard supply/mains voltage (typically 110Vac or 230Vac). These voltages are significantly more common than other voltages as they are used to supply practically everything in domestic and commercial settings. From lights to vacuum cleaners and computer consoles to water heaters, almost every stationary piece of equipment is powered by one of these voltages. Generally, 110V is used for industrial equipment where there is a chance that a cable may be damaged or a short circuit may occur due to damage to the equipment itself. 230V is more often found in stationary equipment where there it is rare for the position of the equipment to change and where there is little chance that such equipment can be damaged, such as offices.
• Higher voltages (415Vac/1000Vac and above). While not technically classed as high voltage until higher than 1000V, it is worth noting that these voltages require extra caution when working around them. These voltages are typically found supplying fixed industrial equipment with high power drain such as recharging stations or some of the larger pieces of machinery found in use on Federation vessels.

 

Working with wiring - why soldering is not a soldier's job

One of the most common tasks of a Systems Technician is having to remake connections and repair faulty wires. After all, the wiring and components are two of the most common faults in electrical systems. Changing out a damaged component is as simple as finding a replacement and switching the two, ensuring all of the connections and any polarities are matched correctly, however changing a damaged wire in its entirety can sometimes be too time-consuming to conduct in the field and so another method needs to be used. This method is known by many names; splicing, butting, crimping, and blocking, to name but a few. This method is characterized by a few key elements and pieces of equipment that shouldn't be left out of any self-respecting technician's toolkit: the butt connector and the terminal strip (chocblock). Both of these items require the wire to be stripped before use. To strip a wire, remove the outer sheathing from the internal conductors of the wire, leaving approximately 6-8mm (1/4 inch) of exposed conductor. If the conductors are thin enough, twist them together. This provides structural support as well as additional cross-sectional area which lowers resistance and therefore increases the cable's ability to transfer electricity effectively. Not only are these techniques quicker and easier to perform, but they are more secure too, and less dependant on skill with a soldering iron, which is quickly becoming a lost trade. The joints and connections created with these items also do not run the risk of accidental short circuits or other grounding/earthing problems.

 

Butt connectors - color coded for various sizes of wire. They are plastic coated metal sleeves that are easily crushed by the specialized crimping tool. If the crimping tool is not available, pliers or teeth will create a sufficient clamping force though it may not be one-hundred percent secure. These connectors are easy to use: simply insert the stripped ends of the wires you wish to join into each end of the connector and crimp the connector closed. This will provide a joint, albeit temporary, allowing electricity to flow again.

Terminal strip - The terminal strip, nicknamed the chocblock, is a slightly more permanent and reusable solution over the butt connectors. It takes a little longer to fit the connections, though this extra time is measured in seconds for an experienced engineer. Terminal strips are similar to butt connectors in function but differ in form slightly in that the conductor securing mechanism is a pair of clamping screws. These clamping screws hold the conductors in place and are releasable, allowing the chocblock to be used again and again.