Three Point Dc Motor Starter Diagram. Now the question is why these types of dc motors require the assistance of the starter in the first place. The 4 point starter has a lot of constructional and functional similarity to a 3 point starter but this special device has an additional point and coil in its construction as the name suggests.
The electromagnet that holds the starter in the run position is in the field circuit. Various types of manual starters for dc motors commonly known as two point three point and four point starters are available. A 4 point starter protects the armature of a dc shunt motor or compound wound dc motor against the initially high starting current of the dc motor.
F shall be connected to either terminal of field winding.
Three point starter construction and working of three point starter diagram drawback when a dc motor is at rest its speed n is zero and therefore back emf e b p ϕzn 60a is zero. Working principle of 4 point starter. All have a face plate rotator switch with a connected group of current limiting resistors. Now if the motor is directly switched to mains then as per motor equation v e b i a r a armature current i a v r a will be very high as high.
