Keep shop voltage under control.Dear Editor, C & E shops need to make sure the source of DC voltage in their shop is correctly grounded. Many of them aren't. If you're working on commo equipment and have noticed sparks Sparks, city (1990 pop. 53,367), Washoe co., W Nev., just E of Reno; inc. 1905. The Southern Pacific RR was the major employer until the dieselization of railroad engines forced the closing (1957) of the railroad shops there. between your work bench or other grounded objects or have been "bitten bit·ten v. A past participle of bite. bitten Verb the past participle of bite " by electricity, you need to check the ground on the central station power supply that provides 28 DC volts. Many of these supplies are capable of producing 200 or more amperes of current. That's enough to cause serious injury! Almost all these power supplies have two output terminals--positive and negative. Neither of these terminals are connected to the power supply's chassis Pronounced "chah-see," it is a physical structure that holds everything or that everything is attached to. A computer's cabinet is often called the chassis. ! Here's what you, need to do: Connect the negative terminal of the power supply to the station ground buss with a cable of sufficient size to handle the entire output capacity of the power supply. Now check the voltage between the positive terminal to the ground. If you get 28 DC volts, you're okay. Don't be fooled by a "no voltage reading" on your meter when you check for voltage between the ground and the negative side of the power source. Verify (1) To prove the correctness of data. (2) In data entry operations, to compare the keystrokes of a second operator with the data entered by the first operator to ensure that the data were typed in accurately. See validate. the connection both visually and with a continuity check with an ohm ohm (ōm) [for G. S. Ohm], unit of electrical resistance, defined as the resistance in a circuit in which a potential difference of one volt creates a current of one ampere; hence, 1 ohm equals 1 volt/ampere. meter. Edward Butorajac Ft Gordon, GA From the desk of the Editor Shop power supplies are often installed by folks who are not aware of the need to have the chassis and the negative terminal of the voltage source A voltage source is any device or system that produces an electromotive force between its terminals OR derives a secondary voltage from a primary source of the electromotive force. bonded together and connected to the station ground for proper grounding. This could lead to a shock hazard, arcing of the chassis to the work bench or other grounded item, or RF burns. Take Ed's advice and check out your shop's power supply for the right grounds. Also, check the power supply TM or manufacturer to make sure that the power supply is installed properly and that tying the secondary to ground is okay. |
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