Current protection is important in a number of electrical applications. For both safety and the protection of expensive, important pieces of equipment, current protection is often required within electrical systems. 

While there are a number of ways to accomplish this goal, PTC thermistors are often used for the job. Let’s take a closer look at what these resistors can accomplish so you can determine if they are right for your project.

What is a PTC Thermistor?

The concept behind a PTC thermistor is quite simple. These resistors are designed to have a positive temperature coefficient, which is where the “PTC” name comes from. As temperature rises, the resistance that is offered by the thermistor increases, allowing circuit designers to tie the flow of current to the temperature that is being experienced. 

This type of resistor is popular because it can be used in a variety of applications. It can be used for current protection – which we will talk more about in a moment – but it can also be used as a time delay function within a circuit, it can be used in the motor starting process, and it can also be used to self-regulate heating components. If you’d like help understanding some of the various ways our PTC thermistors can be put to use, feel free to get in touch with our expert team today. 

Implementing a PTC Thermistor for Overcurrent Protection

Often, fuses are used as a form of current protection, as the fuse will blow if the current exceeds a set limit and the circuit will be broken. The problem with this arrangement is obvious – if the fuse is blown, it will need to be replaced. As a better solution, a PTC thermistor can be used to accomplish the same goal without the downside of ongoing, potentially frequent replacements being required. 

For current protection, you’ll typically be looking at a switched PTC thermistor. This is a type of resistor that maintains a steady level of resistance at a given temperature range, but the resistance will suddenly jump up (or “switch”) once a certain temperature is reached. That design allows the switched PTC thermistor to act effectively as a fuse, only it won’t need to be replaced after the overcurrent event. Once the additional flow of current has abated and the temperature in the thermistor returns to normal levels, the resistance will drop and the performance of the circuit will be allowed to continue once again. 

Protecting circuits from the inevitable, occasional rush of additional current is essential for countless businesses. At the same time, utilizing standard fuses for the job adds a layer of maintenance and ongoing upkeep that is not desirable. The PTC thermistor is an elegant solution to this problem, as it essentially automates the fuse management task. There is no fuse to blow, and the current can go up and down without doing any damage to the equipment that is downstream of the thermistor. 

Order from Calco Electric Today

In addition to our extensive selection of quality products, it’s the expertise of the staff at Calco Electric that allows us to stand apart from the competition. If you would like to learn more about the PTC thermistors we offer, or if you are ready to place an order, please reach out today and we will be happy to serve you.