Slip-ring rotor, 0.3

This equipment examines the duty and steady-state operating behaviour of an electric asynchronous machine with a squirrel-cage rotor. Special attention is paid to the termination, the rated values, the efficiency determination and the machine characteristic curve.

Experimental procedures are carried out with industrially manufactured machines. All test machines have a special base for termination to the machine test system 0.3. All measured values of the alternating current machines are recorded with the machine test CASSY. 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 taken without additional software and the measurement data can be saved locally on the device. The machine test CASSY is used to record the characteristics of the test machines. The power supply for the test machines is partly provided directly from the public supply network.

Learning objectives

• Protective measures and electrical safety.
• Setup and commissioning of electrical machines.
• Use of starting circuits.
• Machine efficiency.
• Assessment of characteristic curves of electrical machines.

The slip-ring motor is a type of asynchronous machine. In contrast to the squirrel cage rotor, the rotor of the slip-ring rotor is designed as a three-phase winding, which is connected to slip-rings and is accessible from the outside via brushes. Slip ring motors are preferably used in drives that require high starting torques with low starting currents. For heavy-duty starting, the slip-ring motor is started with a frequency inverter and controllable rotor resistance so that the machine is not overloaded.

Highlights

• To protect against overheating, the stator windings of the test machines are equipped with thermal detectors.
• In the event of overheating, the machine testing system switches off the load of the test machine, thereby maintaining air cooling. This prevents damage to the test machines.
• The test machines have a didactic terminal board with the winding diagram printed on it.
• All winding ends are led out to safety sockets (4 mm) on the terminal board.
• Computer-aided data acquisition provides meaningful measurement results.
• The arrangement of the 4 mm safety sockets complies with the standards for industrial motors.

Measuring and media system

Machine Test CASSY

The machine test CASSY 0.3 can be quickly operated in all functions directly via the display, the rotary knob and the buttons on the device. All settings and measurement results can be saved on the device and quickly called up again later or simply downloaded.

In addition, the Machine Test CASSY system can be fully controlled in real time via the RJ45 Ethernet, W-LAN and USB-C interfaces.

These interfaces can be used by the following software:

• CASSY Lab 2 for drive and energy technology,
• MATLAB and LabVIEW,
• Lab Docs Editor Advanced.

The following integrated servers are available in the machine test CASSY 0.3 machine test for the local media connection of at least four end devices simultaneously.

Further information can be found in the product documentation 7731901 machine test CASSY 0.3.

Target group

The target group is industrial trainees and students specialising in electrical engineering. The course offers tests at an intermediate level for the vocational school and at the same time provides the necessary insights into the machine behaviour for a scientific interpretation in the bachelor training. The media connection makes the experiments suitable for demonstration in the classroom or a lecture theatre.

The following equipment includes extended experiments with slip-ring rotors.

• E2.2.4.1 Cage rotor 400/690.
• E2.2.4.2 Squirrel cage rotor 230/400.
• E2.2.4.3 Squirrel cage rotor 230/400 IE3.
• E2.2.4.5 Squirrel cage rotor D.
• E2.2.4.6 Multifunction machine.
• E2.5.4.3 Starting large flywheel masses with slip-ring motor.