Potentiometers available on the market consist of several types, namely: carbon potentiometer, wire wound potentiometer and metal potentiometer film.
1. Potentiometer of carbon is a potentiometer made of carbon materials the price is quite cheap but the potentiometer kepressian is very low usually the price of resistance will be very easily changed due to contact shift.
2. Wire wound potentiometer is a potentiometer that uses a very small roll of nickel wire cross sectional size. The accuracy of this type of potentiometer depends on the size of the wire used and the tidiness of the rolling.
3. Metal film is a potentiometer that uses a metal material that is superimposed onto the insulator material
a. Wire Wound b. Slide Resistance c. Carbon
Figure 3.42 Types of Potentiometers
The carbon and film metal potentiometers are rarely used for industrial control because they wear out quickly. The wire wound potentiometer is a potentiometer that uses a fine wire wrapped around a metal rod. The accuracy of a potentiometer depends on the size of the wire. The wire used is usually a nickel wire.
The use of a potentiometer for position control is practical because it requires only one excitation voltage and usually does not require a complicated signal processor. Weakness of potentiometer usage is mainly:
1. Fast wear out due to friction
2. Often the noise arises, especially when the change of position and saaat happened loose contact
3. Easy to attack corrosion
4. Sensitive to impurities
Linear potentiometer is a potentiometer that changes the resistance very fine with the number of turns up to ten times the turn (multi turn). For the purposes of positioning a linear potentiometer sensor utilizing a change in resistance, protection is required if its measurement range exceeds the rating, the high linearity of the result is easy to read but be careful with friction and backlash generated, the resolution is limited to 0.2 – 0.5%
Figure 3.43 Potentiometer test circuit