The experiments are carried out with industrially manufactured machines class 1 kW. The 1 kW machines have a higher efficiency due to the lower winding resistance and come closer to an ideal machine. All test machines have a special base for connection to the Machine Test System 0.3. With the Machine Test CASSY all measured values of the AC machines are recorded. The measured values can be shown directly on the built-in display as a single value, table of a measurement series or diagram. The measurements can be made without additional software, and the measured data can be stored locally on the unit. The Machine Test CASSY is used to record the characteristic curves of the test machines. The power supply for the test machines is partly taken directly from the public supply network.
Objectives
- Protective measures and electrical safety
- Construction and commissioning of electrical machines
- Use of starting circuits
- Efficiency of the machine
- Assessment of characteristic curves of electrical machines
Motors with slip-ring motors (wound rotor motors) represent a type of asynchronous machine. Unlike squirrel cage rotor machines a slip-ring rotor is in the form of a three-phase winding attached to a slip-ring and accessible from the outside via brushes. Slip-ring motors are preferred for use in drives which require high torque but low starting current. Asynchronous machines with slip-ring rotors are increasingly being replaced with conventional machines featuring squirrel cage rotors fed via a frequency converter. Such drives achieve similar operating behaviour to slip-ring rotor motors but they are easier to manufacture and avoid wear to the slip contacts, which undergo both mechanical and electrical wear and tear.
This machine can be operated as synchronous machines with an extra-low voltage source.
Highlights:
- To protect against overheating, the stator windings of the test machines are equipped with temperature detectors.
- In case of overheating, the machine testing system switches off the load of the test machine, thus maintaining the air cooling. This prevents damage to the testing machines.
- The test machines have a didactic terminal board with the winding diagram printed on it.
- The ends of all the windings are led out at the terminal board at safety sockets (4 mm).
- Computer-aided measured value acquisition provides meaningful measurement results.
- The arrangement of the 4 mm safety sockets corresponds to the standards for industrial machines.
All functions of the Machine Test CASSY 1.0 can be operated quickly and directly via the display, the rotary wheel and the buttons on the unit. All settings and measurement results can be saved on the unit and quickly called up again later or simply downloaded.
In addition, the Machine Test CASSY 1.0 is fully controllable in real time via RJ45 Ethernet, W-LAN and USB-C interfaces.
These interfaces can be used by the following software:
- CASSY Lab 2 for drives and energy systems,
- MATLAB® and LabVIEW ™
- Lab Docs Editor Advanced
Several integrated servers are available in Machine Test CASSY 1.0 for the local media connection of at least four end devices simultaneously.
For more details, see product data 7732900 or 7731901 Machine Test CASSY 1.0
The individual equipment is equally suitable for student experiments in the laboratory with low voltage (230 / 400 V three-phase current) and - with a mobile trainer - for teacher demonstration in the classroom. The experiments are carried out according to the 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. The media connection makes the experiments suitable for demonstration in the classroom or a lecture hall.
In the following configurations there are further extended experiments with the slip-ring rotor:
- E2.3.4.1 Squirrel cage rotor, 400/690
- E2.3.4.2 Squirrel cage rotor, 230/400
- E2.2.4.4 Slip-ring rotor
- E2.3.4.4 Squirrel cage rotor D
- E2.3.5.3 Multi-function machine
- E2.5.4.3 Starting of large flywheel masses with slip-ring motor
Topics
- Design and function of a motor with slip-ring motor
- Starting
- Measurement of rotor standstill voltage and rotor current
- Adjusting speed via starting resistors
- Characteristics in motor operation
- Use of slip-ring rotor asynchronous machines as three-phase transformers
- Locus (Heyland circle) diagram
- Open-circuit test
- Short-circuit test
