The motor-generator set provides a range of voltage and frequency combinations. Thus, we can conduct following tests:

Load Test

Load loss measurement is performed at rated frequency by applying rated currents, using an MG set on one of the windings. The other windings are shorted. Voltage drop, current and copper loss will be measured. The accuracy of the frequency required for the test is maintained to be ± 0.01% using an MG set. The tests can be performed at 50 or 60Hz, and also either in 3Ph, or in 1Ph mode. The generators are specially designed for low power factors and low residual voltage.

No-Load Loss Test

This test is performed to measure no-load current, and no load loss of transformers at rated frequency and voltage. The loss measurement is carried out precisely at rated frequency using our MG set and controls.

Temperature Rise Test

The temperature rise test is carried out precisely at the rated frequency either at 50Hz or 60Hz. This test is carried out in the short circuit mode by supplying power at impedance voltage, and at rated frequency throughout the duration of the test. Our MG set and controls are suitable for delivery rated power on a continuous basis.

Induced Over Voltage Test

(Double voltage and double frequency) The transformers are tested at double voltage and frequency using our MG sets and controls. The output of the generator is normally connected to a booster transformer with multiple tapings, and then to the test transformer.

This is the very first time that a system has been designed and successfully executed by any company in India. This is used for carrying out short circuit tests on various electrical equipment in off-line mode, and comprises a motor-generator set and control panels.

The AC motor is directly coupled to the AC generator, and mounted on a common base frame. The other side of the AC generator is coupled to a flywheel. The generator can deliver its rated power of 50 MVA for 1 second. The testing can be performed either at 50 or 60Hz.

The system is designed such that the short circuit is derived from the flywheel instead of from the motor (the motor power will be electronically disabled during actual testing and automatically switched on at the end of the test.) Thus, the actual SC power is obtained from the stored energy from the rotating mass. It is expected for the generator frequency to fall by about 10% on full load conditions in 1 second.

A static excitation system is provided for precise control of the short circuit power.

A PLC panel is provided for necessary interlocking for various sub systems, thus minimizing the interconnection of cables and improving flexibility in operations. A SCADA is provided to lock the data online and stored in the system. The data can be retrieved from the memory for off-line measurement and analysis of the short circuit parameters. Some of the features include a programmable sequencer, point-on-wave control etc., which are very essential for performing accurate short circuit tests.

Typically a frequency converter comprises a motor (AC/DC) – generator set, converter transformer, variable speed drive (AC/DC), protection and excitation controls for generators, control desk with integral PLC and SCADA for remote operation from the control room.

The MG-Set is designed for no load testing of LT motors, HT motors, and DC motors. The system comprises a motor-generator set, which develops power that is connected to the motor under test directly for LT motors, or through a step-up intermediate transformer for HT motors. For the testing of DC motors, controlled power from the DC Drive is directly fed to the test motors.

The system is designed for no load testing of LT motors, HT motors and DC motors.

Testing of these motors can be done in any of the following modes:

• Three LT induction cage motors up to a maximum rating of 600 kW, 415V, 50Hz each, at a time
• One HT induction motor up to a maximum rating of 2 MW, 3.3kV/6.6kV, 50Hz, at a time
• Two DC motors up to a maximum rating of 1300 kW, 440V each, at a time