Digital control of ambient relative humidity for measurement of electrical resistance of cashmere fibre

摘要

The dynamic equations of testing laboratory have been studied to determine the electrical properties of cashmere fibres in constant and definite relative humidity according to the principle of control design. It is observed that the transport time (dead time) has a major effect on the stability limitation than the sampling time. Using these limitations, the equation of proportional integral differential control has been obtained. The variation in relative humidity is found to be less than 0.5%, The electrical resistance of the fine undercoat cashmere fibres is considerably greater than that of the coarse outercoat cashmere fibres. The difference depends on the breeds. With the increase in relative humidity, the difference in the electrical resistance of fine undercoat and coarse outercoat cashmere fibres decreases.