Megger

The megger is an instrument used for the measurement of high resistance and insulation resistance, Essentially the Magger insulation tester consists of a hand-driven d.c. generator and a direct reading true ohmmeter. A simplified have of electrical connections of the instrument is shown in fig. 6.242 Permanent magnets provide the field of operations for both the generator & the ohm-meter. The moving element of the ohm-meter consist of tercet waves known as real (or deflecting) turn, jam (or apply) coil and compensating coil, which are mounted rigidly to a pivoted central shaft and which argon free to rotate over a stationary C-shaped supplicate core. The coils are connected to the circuit by means of pliant leads (or ligaments) that exert no restoring torque on the moving element. and so the moving element may take up whatever position over the scale when the generator handle is stationary. The sure (or deflection) coil is connected in series with th e resistance R between one generator last-place and the test net marked L. The series resistance R protects the current (or deflecting) coil in case the test terminals are short-circuited and also falsify the range of the instrument.

The shove (or control) coil in series with a compensating coil and protection resistance R is connected across the generator terminals. Compensating coil is provided to obtain better scale proportions and to play the instrument a static. When the current from the generator flows finished pressure coil, the coil tends to set itself at right angles to the field of the dark magnet. W ith the test terminals open, corresponding t! o infinite resistance, no current flows through deflecting coil. The pressure coil thus governs the motion of the moving element, put forward it to move to its extreme counter-clockwise position. The point on the scale indicated by the pointer under this condition is marked infinite resistance. certain coil is wound to produce clockwise torque on the...If you want to get a full essay, order it on our website: OrderCustomPaper.com

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