Dead Zone 2n4b6k

Dead Zone: It is defined as the largest change of input quantity for which there is no output of the instrument. For example the input applied to the instrument for may not be sufficient to the overcome the friction and will in that case, not move at all. It will only move when the input is such that it produces a driving force which can overcome friction forces. And other factors which produce dead zone are backlash and hysteresis in the instrument. The term “DEAD ZONE” sometimes used interchangeably with term hysteresis. However, it may be defined as the total range of input values possible for a given output and may thus be numerically twice the hysteresis defined in figure.

M e a s u r e d q u a n ti t y

100 Measured Quantity

Dynamic Error

80 Instrument Reading Measuring Log

60 Dead Zone 40

20

Dead time

Example: The dead zone in a certain pyrometer is 0.125 % of span. The calibration is 400ºc to 1000ºc. What temperature change might occur before it is detected?

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DEAD ZONE

Span = 1000 – 400 = 600ºc Dead zone = (0.125/ 1000) x 600 A change of 0.75ºc must occur before it is detected.

Emp: 20012413

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Time

Solution: -

Bhavesh

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Mahir

Emp: 20012406

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