Thermistors and Temperature Measurements

Play an AI-generated podcast conversation about this lesson

What is the main component of an RTD?

A rod-shaped tube, often a length of fine coiled wire wrapped around a ceramic or glass core.

What is the typical material used to make an RTD element?

A pure material, often platinum, whose resistance at various temperatures has been documented.

Why is platinum well suited for industrial temperature measurement?

It is relatively immune to electrical noise.

What is the significance of the '100' in Pt100?

It represents the resistance of 100Ω at 0°C. Signup and view all the answers

What is the purpose of the thermowell in an RTD?

To house the RTD element and protect it from damage. Signup and view all the answers

What is the predictable change in an RTD element that is used to determine temperature?

A change in resistance as the temperature changes. Signup and view all the answers

What type of material is a thermistor, and how does its resistance change with an increase in temperature?

A thermistor is a type of semiconductor, and its resistance decreases as temperature increases. Signup and view all the answers

What is the difference between NTC and PTC thermistors?

NTC (negative temperature coefficient) thermistors have a decreasing resistance with increasing temperature, while PTC (positive temperature coefficient) thermistors have an increasing resistance with increasing temperature. Signup and view all the answers

How does the resistance of an NTC thermistor change with temperature?

The resistance of an NTC thermistor increases in a non-linear fashion with decreasing temperature. Signup and view all the answers

What type of applications typically use lower resistance thermistors (2252 to 10,000Ω)?

Low-temperature applications (-55 to approx. 70°C) typically use lower resistance thermistors. Signup and view all the answers

What is the primary use of PTC thermistors?

PTC thermistors are often used for circuit protection. Signup and view all the answers

What is the term used to describe a thermistor, based on its characteristics?

A thermistor is often referred to as a 'thermally sensitive resistor'. Signup and view all the answers

What is a major difference between thin-film RTD elements and wire-wound RTD elements?

Thin-film elements are more resistant to damage from shock or vibration. Signup and view all the answers

What is the benefit of using wire-wound RTDs with ceramic cores?

They can accurately measure extremely high temperatures. Signup and view all the answers

What are the RTD accuracy classes, and what is the temperature range they can measure?

The accuracy classes are B, A, AA, and they can measure temperatures from -196 to 600 °C. Signup and view all the answers

Why are wire-wound RTDs more expensive to manufacture than thin-film RTDs?

They require skilled labor and advanced assembly facilities. Signup and view all the answers

What happens when an RTD operates outside its range?

Possible damage may occur, which affects the accuracy of the reading. Signup and view all the answers

Why is an output amplifier necessary for RTDs?

To amplify the output for proper reading. Signup and view all the answers