Types of Motor Protection
- Motors need protective measures to keep them from breaking down.motor image by Petr Efremov from Fotolia.com
Motors power a variety of machines from cars to automated manufacturing equipment. When the motors break down, the results can not only be costly but can actually be dangerous to human life. As a result, there are many ways in which motors are protected from damage, both from normal wear and tear and from unexpected circumstances. - Motors can sometimes have power surges. These surges can cause electricity to pass through the motor very quickly, which can burn, damage and sometimes ruin different parts of the motor, most often after the motor windings are destroyed. The motor becomes overloaded because the friction conditions in the machine change, because the pumps sometimes have to work with different pressure heads, because some tools in the motor engage more powerfully and the transport carriages have greater loads, because breaking operations take too long and because rotors become blocked. The circuit breaker surge protector uses a disconnecting device or an emergency-stop switch to bring the power surge to a halt.
- With three-phase motors, thermal overload relays are installed with microprocessor-based motor protective relays that provide protection from both short-circuits and overloads. Resistance temperature devices display the temperature of the motor and provide a warning when the motor appears to be overheating.
- Eutectic alloys are used to detect overheating and shutting down operations before damage can occur. The eutectic alloy melts very easily, turning from solid to liquid without going through a putty stage. When the eutectic alloy melts, the ratchet wheel rotates freely; when the motor cools, the alloy hardens and operations can resume. Really bad faults damage thie heater element, thus requiring that the heater element be replaced, but most often the switch will operate before temperatures get too high.
- A motor can contain a very large number of parts, many of which can break or wear down to the point where they are no longer useful. In these cases, motors can come with specialized sensors that notify when a particular part is broken. This allows preventative maintenance to be performed very quickly before the motor can malfunction and cause a loss of property and productivity or cause an injury.
- Motors usually have some kind of lubrication in the form of an oil so that metal parts are not rubbing against each other. When metal parts rub against each other, this will cause friction, which can damage the metal parts and cause them to wear down more quickly. Lubrication provides a more giving barrier to the metal parts. Some motors have parts that are powered by hydraulics, which are reliably compressible liquids that can carry mechanical energy, which minimizes friction even further.
