Dc Motor

EXPERIMENT 1: Characteristics of DC Motor

Abstract

This experiment is conducted to determine different DC motor characteristic. We are to conduct 5 test that include determine the armature and field resistance, determine the armature voltage-speed relation, armature current and speed with field current relation, armature current-torque relation, load test to motor efficiency. This experiment is conducted with a DC motor, ohmmeter, voltmeter, ammeter, power supply, and wires.

Objective

1. To understand the motor and load to be used

2. To determine the armature voltage-speed relation

3. To determine the armature current and speed with field current relation

4. To determine the armature current-torque relation

5. To determine the load test to motor efficiency

Introduction

A simple introduction to dc motors is that Direct-Current motors transform electrical energy into mechanical energy. They drive devices such as hoists, fans, pumps, calendars and etc. Most electric motor uses electricity to create magnetic field that interacts with current-carrying conductor to generate force. A DC Motor is a direct current motor. This motor uses dc current instead of ac current. The figure below shows the working principle of dc motor.

Figure 1; Working principle of DC motor (hyperphysics.phy-astr.gsu.edu)

* When current is passes to the armature, it will create a magnetic field. This interacts with the main field poles of the permanent magnet and causes force to produce and turn the armature.

* When it turns half way, the brushes will have a gap which prevents the current from passing the current that will cause the armature to turn the other way. Therefore current will only passes in one direction. Thus, the motor will turn one way only.

These devices may have a definite torque-speed characteristic (such as a pump or fan) or a highly variable one (such as a hoist or...