Interested to Buy Any Domain ? << Click Here >> for more details...
1. Why a DC motor starter is called 3 point starter
- 21 Answers
- 80854 Views
- ABB, CG, College School Exams Tests, Crompton Greaves, Infosys, Siva, I also Faced
- E-Mail Answers
Answer Posted / hima teja
3 POINT DC STARTER
3 point DC starter is a unit intended to limit the starting current in a DC circuit. This starter is a must for any DC motor applications. This starter has three functions.
(a) To provide series resistance in a DC circuit when this starter is in START position. I.e. In STARTposition full resistance is included, and is reduced to zero ohms when the handle is moved to ON position, in discrete steps. The starter is held in ON position by an electromagnet. At this ON position the DC circuit gets its full current from the DC Rectifier unit. In the case of a DC motor, this is
connected in series with the armature circuit, to limit the starting current and eventually this resistance is CUTOUT, from the circuit. There by enabling the motor to run at it’s full armature current. Therefore this starter acts as a first order protection circuit, in between a DC rectifier unit and the DC circuit.
(b) No Volt Coil (NVC) – This is normally connected to Field circuit in a DC motor. In case of a failure in current in this circuit, for any reason, namely accidental tripping, or unintentional break in field circuit, this coil will provide a signal to the electromechanically held arm (handle) to release, and the starter is switched to OFF position, thereby providing safety to the system.
(c) Over Load (OL) release switch – This is connected in series with the armature circuit. In case of current beyond the rated current of this coil in the circuit, this automatically trips the electromagnet, which is holding the handle in ON position. Thereby tripping the starter from being over loaded
| Is This Answer Correct ? | 6 Yes | 1 No |
Post New Answer View All Answers
how is find out kwh step by step
Name the test signals used in control system
For a spring controlled governer the relation F = ar+b (F is the controlling force, r is the radius of rotation a and b are constants), indicates that the governer is
How to synchoronize the generator (with gcb,GT) to grid????? ????? from Grid iam getting power (rated 400kv/20kv) through GT and its goes to UAT.,,ST.,, now my generator(rated 20kv ) ready.,, now iam closing my GCB.,, in GT iam suddenly giving 20kv on that Gt.,, what will happend
how to Select its CORE in electrical cables based on its applications? or Application of various types of electrical cable based on it CORE?
Define newton's law of viscosity.
difference between Ac and Dc mcb ????
what is the constructional difference between a power transformer and potentian transformer?
What is the minimum distance to be maintained in between HT panel and LT panel and Instrument panel as per IEC and NEC standards?
Actuality I have at home electrical panel with 220v 50hz, and I want to converter from there to 110v 60hz, to wiring on the half of my house. Also I like to keep another half of my house with the original 220v 50hz. What is the best and safety way to do?
What is meant by impedance? difference between high & low impedance ?
What is the method of estamating of cable, CB,MCB ?
How to calculate the heat load for a electrical room
If 22 KV HT line, Current transformer is 25/5 then how to calculate multiplying factor.
ACB & VCB how do work and saftes and how can maintenance in this and parts name show with picture
