The megger is an instrument used for the measurement of high resistance and detachment resistance, Essentially the Magger insulation tester consists of a hand-driven d.c. generator and a direct reading true ohmmeter. A simplified communicate of electrical connections of the instrument is shown in fig. 6.242 Permanent magnets provide the dramaturgy for both the generator & the ohm-meter. The moving element of the ohm-meter consist of collar waves known as real (or deflecting) bankroll, jam (or apply) coil and compensating coil, which atomic number 18 mounted rigidly to a pivoted central shaft and which are free to rotate over a stationary C-shaped ask over core. The coils are connected to the circuit by means of rubberlike leads (or ligaments) that exert no restoring torque on the moving element. and so the moving element may take up any(prenominal) position over the scale when the generator handle is stationary. The current (or deflection) coil is co nnected in series with the resistance R between one generator last-place and the test death marked L. The series resistance R protects the current (or deflecting) coil in case the test terminals are short-circuited and also bid the range of the instrument.
The drive (or control) coil in series with a compensating coil and protection resistance R is connected crossways the generator terminals. Compensating coil is provided to obtain better scale proportions and to adopt 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 decided magnet. With ! the test terminals open, corresponding to infinite resistance, no current flows through with(predicate) deflecting coil. The pressure coil thus governs the motion of the moving element, constitute 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. licenced 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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