Bead Metal Lug Ceramic PTC Thermistors Limit Temperature Sensor MZ6 For Temperature Protection

How Does PTC Thermistor Temperature Protection Work?

PTC thermistor for temperature protection works in this way, the PTC thermistor is mounted in thermal contact with the equipment to be protected, and connected into the bridge arm of a comparator circuit, such as shown in Fig. 1.
At normal temperature, the PTC thermistor resistance (Rp) is lower than Rs (see Fig. 2), so the comparator’s output voltage VO will be low.
If an equipment over temperature occurs, the PTC thermistor will quickly heat up to its trigger or nominal reference temperature Tn, whereupon its resistance will increase to a value much higher than Rs, causing VO to switch to a high level sufficient to activate an alarm, relay or power shutdown circuit.

Typical Application

· Limit temperature measurement of Industrial electronics application.
· Power supplies, switch power supply.
· Home appliances, such as dish washers, washing machines, ironing machines, electric cookers, etc.
· Electronic data processing and communications engineering (DC/DC converters).
· Motor windings overheating Protection.
· Automotive electronics.
· Semiconductor heatsinks, enclosure panels, temperature-limited transistors.
· Lighting applications.

Features

* 2 Outlook construction: A-radial leaded epoxy resin coated form, B-metal tag lug form.
* Screw type metal cases or other construction can be made upon customer request.
* PTC thermistor Protection temperature 60C to 130C. 60C, 70C, 80C, 90C, 100C, 110C, 120C, 130C.
* Quick response.
* Long stability.
* Small dimension, convenient for installation.
* Do not need to be reset after protection.

Dimension (mm)

Selection Table

What Is PTC Thermistors Limit Temperature Sensor ?

PTC Thermistor Limit Temperature Sensor is ceramic PTC thermistor disk in radial resin bead or metal lug construction, applied for temperature sensing and temperature protection due it switches at one particular temperature.

PTC thermistors with their very steep curves are very suitable for the monitoring of temperature limits and consequently for switching on a fan when a particular temperature is reached.

Making use of the characteristics that the resistance of ceramic PTC thermistors increases sharply above curie temperature, when ambient temperature increases abnormally, protective circuit installed PTC thermistor will turn on or cut off loop through resistance changing, achieving thermal protection purpose.

PTC thermistors protect such equipment and components as motors, transformers, power transistors and thyristors against over-temperature.
A PTC thermistor is less expensive than a thermostat, and its switch temperature can be more accurately specified. It is also smaller and easier to design-in to electronic circuitry. Therefore PTC thermistors can be ideal devices for temperature detection, monitoring, indicating, limiting and over (excessive) temperature protection.
PTC Thermistor Limit Temperature Sensor RT Graph

A further advantage of the PTC temperature characteristic is that PTC thermistors can be connected in series and thus, in their function as temperature sensors, can very easily monitor several hot spots.

As soon as one of these PTC sensors in a series connection exceeds the specified limit temperature, the circuit switches to the high-ohmic state.
With PTC thermistors as temperature sensors, only the steep region of the R/T characteristic is used.

PTC thermistor is only useful as a temperature measuring device over a relatively short range of temperatures near the switch temperature.
The resistance of the PTC thermistor is to be regarded as a function of the ambient temperature [RPTC =f(TA)].
The precondition for this relationship between resistance and ambient temperature is that self-heating.