Motor starters may resemble a relay and its functioning. It is a specially designed electromechanical equipment and switches. The main function of a starter connected to a particular motor is to switch that motor on and off. However, a starter is an improvement over a relay. It can also protect the motor from an overload of current. Because other equipment like relays can also be used for operating a motor automatically, the main benefit of using a starter is to protect the motor from the faults. As of now, a motor starter can be procured in many different sizes and ratings and may specifically suit an AC motor.
Why Use A Motor Starter
The main concern and problem associated with using a three-phase induction motor is a high fluctuation in the EMF (electromagnetic force). Because there is a maximum slip present when a motor is at a standstill, a high EMF is induced within the rotor when the motor is started or powered on. At this point, the starter winding will draw very high current from the main supply, as the motor requires a high current. It has been found that the initial current that is drawn to a motor can be up to 8 times higher than its full-load current carrying capacity. The excessive current and voltage can damage the windings of the motor. It may also cause a large drop in the voltage across the mains lines as a side effect. Because there is a voltage spike resulting from an uncontrolled flow of current, the other appliances (which are connected to the line) may also be impacted adversely. That is why a starter is required to limit and control the starting and initial current, so that the main motor as well as other adjoining equipment of the line, do not get adversely impacted.
How Does The Motor Starters Provide Desired Benefit
The majority of the motor starters used nowadays consist of a bimetallic strip. Following the timed-overload concept ensures that an overload current is only allowed for a short time (can be as low as a few seconds). The motor stops when a current exists for more than this period.
In an electrically operated motor starter, the electromechanical relays (also called as contactors) provides for the switching of the conductors carrying electricity and power. The switch contacts are pulled automatically when the contactor’s coil is energized, as an electromagnetic field is produced. Also, the start button of the starter will have to be pressed (after a power failure) to come into operation.
A motor starter may be necessary when a safety measure has to be included in the line and the motors’ operation. Many different types of motor starters are available today. The varieties may include the soft-start solid-state starter (for general-purpose functions including generators and conveyor systems), the wye-delta starter OEM (for the control systems that may not have the timer functionality initially), the delta open transmission starter (used for compressors and air pump.)
As the process may have a unique configuration, it is essential to consult a leading and reputed manufacturer of industrial equipment to find the best and most appropriate starters and panels for particular motors and machinery.