A variable resistor that is utilized in controlling current is known as a rheostat. This device helps in varying the resistance in an electrical circuit without any interruption. The construction of a rheostat is much like that of the potentiometers. Even when three terminals are present, it utilizes only 2 connections, like a potentiometer. One of the connection is made with the wiper and the other one is made to the resistive element. Unlike the potentiometers, rheostats can convey a noteworthy current. Thus they are generally manufactured as wire wound resistors. The resistive wire is twisted around a protecting ceramic core and the wiper slides over the windings.
Rheostats were most commonly utilized in power controlling devices, for example, to operate the speed of motors, to control the intensity of light (dimmer), in ovens and heaters. These days they are not utilized for this capacity any longer. The reason behind this is because of its low efficiency. Because of its characteristic of variable resistance they are generally used for calibration in a given electrical circuit. In these cases, they are balanced distinctly during creation or circuit tuning. In these cases generally, trimpots are utilized, wired as a rheostat.
Types of Rheostat
There are many types of Rheostat. Let’s look at them below:
- Rotary Rheostat – As the name suggests, the rotary rheostat comes with a rotary resistive path. These have found its utilization in power applications. This kind of rheostat has a shaft which is mounted by a wiper. The wiper is just a sliding contact for a rotary rheostat that can pivot over three-fourth of a circle.
- Linear Rheostat – This kind of rheostat comes with a linear resistive path. The path is glided by the sliding terminal. Here we have got 2 fixed terminal but only one of them is used. The other one is attached to the slider. These are generally utilized in laboratory applications. For the most part, a wire-wound resistive way along with a linear cylinder-shaped material is utilized.
- Preset Rheostat – Whenever rheostats are utilized in the printed circuit board, they are either utilized as preset rheostats or trimmers. Trimmers are a small rheostat generally used in circuits for calibration. Though there is an option of 2 terminal trimmers, in most of the cases 3 terminal potentiometer trimmer is utilized as a 2 terminal rheostat.
Applications of a Rheostat
One of the most important applications of the rheostat as discussed above is to operate the flow of current. All of its other application is derived from this current controlling capability of the rheostat. For example, the rheostats are used to limit the flow of current such that high current faults could be prevented. It is important to choose the size of the rheostat according to the current requirement. For instance, if you have got a high current circuit then you need to have a rheostat of larger size. These kinds are used in dimmer circuits, in heaters, ovens as well as speed control circuits in motors.
This was all we have regarding Rheostat. Hope you liked the article. Brands that manufacture them are Ohmite, Vishay, and TE Connectivity. Make sure to check them out using the links as provided.
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