Search results
Results from the WOW.Com Content Network
When measuring earth resistance with an instrument, it is important to know some of its basic characteristics in order to accurately measure the soil resistance and to properly size the grounding installation. Most importantly, the range of resistance the device measures. Usually the range is three or four degrees.
In electronics, a continuity test is the checking of an electric circuit to see if current flows (that it is in fact a complete circuit). A continuity test is performed by placing a small voltage (wired in series with an LED or noise-producing component such as a piezoelectric speaker) across the chosen path.
A GCM or ground continuity monitor (also called a ground integrity monitor or ground continuity tester) is an electrical safety device that monitors the impedance to ground of a temporary electrical circuit and can provide indication (or protective trip) in the event impedance rises to an unsafe value. A GCM is either an external testing device ...
The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection, and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss.
For choosing a grounding rod there are several selection criteria such as: corrosion resistance, diameter depending on the fault current, conductivity and others. [30] There are several types derived from copper and steel: copper-bonded, stainless-steel, solid copper, galvanized steel ground.
Hydraulic roughness is the measure of the amount of frictional resistance water experiences when passing over land and channel features. [1] It quantifies the impact of surface irregularities and obstructions on the flow of water. One roughness coefficient is Manning's n-value. [2]
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
A minimum acceptable resistance value is usually specified (typically in the mega ohm (MΩ) range per circuit tested). Multiple circuits having a common return may be tested simultaneously, provided the minimum allowable resistance value is based on the number of circuits in parallel. Five basic isolation test configurations exist: [3]