Synchronous Machines, 1.0 kW

The experiments are carried out using industrial-design machines. All the test machines possess a special base for connecting the Machine test system 1.0. The testing system can be used to record the characteristics of the machines under test. Power for the machines is supplied either via the mains or by special laboratory power supplies.

Objectives

• Protective measures and electrical safety
• Setting up electrical machines and putting them into operation
• Use of starting circuits
• Assessment of electrical machine characteristics

Synchronous machines are among the typical kinds of three-phase machine. Unlike asynchronous (induction) machines they run at a constant speed which is solely dependent on the frequency of the rotating field. The speed is not therefore influenced by the torque. Apart from their use as motors, e.g. for conveyor belts, textile machines, paper winding and other winding machines, they are used as synchronous compensators. This uses an effect whereby both inductive and capacitive reactive power can be taken from the supplying mains network. For this reason, they are popularly used instead of large capacitor batteries to compensate for inductive reactive power, such as arises e.g. in the operation of electric motors.

Features

• In order to protect against overheating, the stator windings of the machines to be tested are equipped with temperature sensors
• Should overheating occur, the machine test system automatically shuts down the test machine, thus preventing any damage to it.
• The machines to be tested are equipped with an educationally designed terminal board with the winding configuration printed on it.
• The ends of all the windings are connected to the terminal board and can be accessed via 4-mm safety sockets
• Computer-supported acquisition of measurement data provides for meaningful measurement results.
• Machines in the 1 kW rating class have a powerful and realistic operating response
• In comparison to smaller machines, their characteristics display distinctive features related to the design.

The complete equipment set is equally suitable for student experiments in laboratories with low voltage supplies (400 V three-phase) and for setting up on a mobile trolley for demonstration by teachers in a classroom. The procedures for the experiments are provided in a printed manual.

The target group is made up of commercial apprentices and students of electrical machine construction. The course offers experiments at an intermediate level and also allows for the necessary insight into machine behaviour for scientific interpretation at undergraduate level.

Synchronous motor topics

• Non-salient-pole and salient-pole rotors
• Voltage equations
• Equivalent circuit and vector diagram
• Operation with no-load and with a permanent three-pole short-circuit
• Locus diagrams and control characteristics
• Torque and loading
• Potier diagram and armature reaction
• Synchronisation and use of multiple machines in parallel
• Starting methods for synchronous motors
• Control of reactive power
• Power performance

Synchronous generator topics

• Voltage generation
• Excitation of synchronous machines
• Operating response
• Armature current and torque
• Braking operation and locus diagrams
• Starting and synchronisation
• Single-phase generators

Main components: