Four Point Starter

There are various types of manual starters accessible for DC motors specifically 2-point starters, 3-point starters, and 4-point starters. A measure of similarity exists between these starters. The three kinds of starters incorporate a switch specifically a face plate rotator through a related arrangement of the current limiting transistor. The primary and shared distinction among these initiating points lies in the absence of a voltage coil, commonly referred to as NVC (no voltage coil). In a 4-point starter, there is no voltage coil it is connected directly to the voltage supply. A starter isn’t required for a 6V or 12 V DC motor, and it tends to be run directly. External resistance, a no-volt release coil, and an overload release coil make up a DC motor starter. This article discusses the construction and working principle of a 4-point DC motor starter.

What is a 4-Point Starter?

The functional characteristics of a 4-point starter are like a 3-point starter. Four-point starter works as a current controlling device in the lack of back EMF while beginning the running of the DC motor. Additionally, a four-point starter works as a protective device. The primary distinction between a 4-point starter compared with a 3-point starter is, the holding coil is detached from the shunt-field circuit. The stud is then connected in series to the line’s current-limiting resistance (R). The contact points of the starter are called studs.

Working Principle of 4 Point Starter

The principle of operation of a four-point starter is that it protects the armature of a DC shunt motor or compound wound DC motor from the DC motor’s initial high starting current. Although the 4-point starter has an additional point and coil in its construction. It shares many of the same constructional and functional characteristics.

Applications of Four-Point Starter

• DC Motor Control: In various industrial applications, four-point starters are mostly used for starting, controlling the speed, and protecting DC motors.
• Electric Traction: They are used in electric locomotives and other traction systems that use electricity to control speed precisely and accelerate smoothly.
• Machine Instruments: Four-point starters find applications in machine devices like machines, processing machines, and bores to control the speed and ensure a continuous begin to stay away from mechanical burdens.
• Conveyor Systems: In conveyor systems, where controlling the speed of the motor is fundamental for keeping a consistent progression of materials, four-point starters are regularly used.
• Lifts and Cranes: In elevator and hoist systems, four-point starters are used to control the motor’s acceleration and deceleration.

Construction and Operation of 4 Point Starter

• ‘L’ Line terminal it is connected with positive of supply.
• ‘A’ Armature terminal it is connected with the armature winding.
• ‘F’ Field terminal it is connected with the field winding.
• Like in the 3 point starter, and in addition to it there is,
• A fourth point N it is connected with the No Voltage coil NVC

The main difference in the event of a 4 point starter is that the No Voltage coil is linked independently to the power source via the fourth terminal designated as ‘N’ in addition to the ‘L’, ‘F’ and ‘A’. The NVC’s performance is unaffected by any change in the field supply current as a direct result of this. In this way it should be ensure that no voltage coil generally produce a power which is sufficiently able to stand firm on the handle in its ‘RUN’ situation, against the power of the spring, under every one of the functional circumstances. Such a current is changed through No Voltage Loop with the assistance of fixed opposition R associated in series with the NVC involving fourth point ‘N’ as shown in the figure below.

Construction and Operation of Four Point Starter Diagram

From above discussions main fact is that the four-point and three-point starters are identical in every other way, just like a variable resistance with multiple sections, as shown in the previous figure. The contact points of these sections are referred to as studs and are designated separately as OFF, 1, 2, 3, 4, 5, and RUN. The handle can be manually adjusted to control the starting current at gathering speed over these studs.

Now what we understand that its approach to working we should have a more critical gander at the diagram given previously. Taking into account that supply is given and the handle is taken stud No.1, then, at that point, the circuit is finished and the line current that starts coursing through the starter. In this present circumstance we can see that the ongoing will be separated into 3 sections, coursing through 3 unique focuses.

First section moves through the starting resistance (R1+ R2 + R3… ..) and afterward to the armature.

second section moves through the field winding F.

Third part moving through the no voltage coil in series with the defensive resistance R.

So the highlight be noted here is that with this specific plan any adjustment of the shunt field circuit achieves no adjustment of the no voltage coil as the two circuits are independent of one another.

This basically implies that the electromagnet pull oppressed upon the soft iron bar of the handle by the no voltage coil at all marks of time ought to be sufficiently high to keep the handle at its RUN position, or rather forestall the spring force from reestablishing the handle at its unique OFF position, regardless of how the field rheostat is changed.

This denotes the functional contrast between a 4 point starter and a 3 point starter. As in any case both are practically comparable and are used for limiting the starting current to a shunt wound DC motor or compound injury DC motor, and in this way go about as a protective device. The 3 point starter. This achieves some differences in its usefulness, however the essential functional trademark continues as before. The fundamental difference in the circuit of a 4 point starter when compared with 3 point starter is that the holding coil is taken out from the shunt field current it is connected directly to across the line with current limiting resistance in series.

Advantages and Disadvantages of 4 Point Starter

Given Below are Advantages and Disadvantages of Four-Point Starter :

Advantages

• Smooth Starting: Four-point starters offer smooth and slow speed increase toward the DC motor, decreasing mechanical pressure and wear.
• Control of Speed: These starters give successful speed control by changing the armature resistance, taking into consideration exact command over the motor speed.
• Overload Protection: As far as possible the beginning current, shielding the motor from abrupt over-burdens and expanding its functional life.
• No-Volt Release: The consideration of a no-volt discharge coil upgrades security by separating the motor in case of a power disappointment, forestalling startling restarts.
• Reversing Capability: Some four-point starters consider the inversion of the motor course, making them flexible for applications that require bidirectional movement.

Disadvantages

• Complex Development: Four-point starters can be moderately perplexing as far as development and wiring, which might expand the expense and upkeep necessities.
• Energy Loss: The consideration of protections in the armature circuit prompts energy misfortunes as intensity, diminishing the general productivity of the system.
• Limited to DC Motors: Four-point starters are only suitable for DC motors and cannot be used with AC motors, limiting their use in some systems.
• Maintenance: The protections in the starter might require occasional support, and inability to do so can influence the exhibition of the system.
• Size and Weight: The extra parts, for example, protections and the no-volt discharge coil, can add to the general size and weight of the starter, which might be a worry in space-compelled applications.

Conclusion

In conclusion, the four-point starter is a flexible device broadly utilized in different applications requiring controlled beginning, speed guideline, and security for DC motors. It has a number of benefits, including smooth starting and overload protection, but it also has some disadvantages, like complexity and energy losses. The decision of utilizing a four-point starter relies upon the particular necessities of the application and the motor system.

FAQs on 4 Point Starter

Could a four-point starter at any point be utilized with AC Motors?

No, four-point starters are designed specifically for DC motors and are not suitable for use with AC motors.

In a four-point starter, what is the purpose of the no-volt release coil?

The no-volt discharge coil detaches the engine in case of a power disappointment, forestalling startling restarts when power is reestablished and improving security.

How does a four-point starter control the speed of a DC engine?

By changing the armature resistance in advances, the four-point starter controls the current flow to the motor, in this way directing its speed.

Could a four-point starter at any point be utilized for bidirectional motor rotation?

Some four-point starters are intended to permit bidirectional engine turn by integrating additional switching arrangements.

What are the most common uses of four-point starters in modern settings?

Four-point starters find applications in different modern settings, including electric traction systems, machine devices, conveyor systems, and lifts, where exact engine control is fundamental.