VFD-fed AC Induction Machine

1. Make sure the three-phase disconnect switch is off.

2. Check that the VARIAC is at 0%.

3. Perform the following connections at the machine and VARIAC terminals:

1. Connect the induction machine stator terminals to the drive output (right-side connectors, when looking at the front of the drive).
2. Connect the drive input (left-hand set of connectors, when looking at the front of the drive) to the VARIAC output.
3. Connect the VARIAC input to the three-phase receptacle on the bench.
4. Before power is applied, turn the dial on the VARIAC up to 75%. This starts the drive at about 210 V line-to-line later in the experiment.
5. Turn on the three-phase disconnect switch. The main screen on the VFD should turn on and display "F000".

4. Press the "Lo/Re" button once to put the drive in local mode - the redlight on that button should turn on.

1. The "Lo/Re" button allows the user to make a selection between the local (Lo) frequency setting and the remote (Re) frequency setting.
2. The user is able to change the frequency (f), and the drive automatically sets the corresponding voltage (V) to maintain a constant V/f ratio.

5. Check that the drive parameters are the same as those shown in Table 1.

6. To perform basic voltage, current, and frequency measurements:

1. Cycle through the menu and find the display with a "0.0u" after it - this displays the measurement of the voltage fed to the motor.
2. From there, scroll up once to a screen that reads "0.00A" - this displays the current measurement when the drive is running.
3. The next screen up from that reads "0.00" - this is the frequency measurement.

7. To set a different output frequency, and thus set a different motor speed since speed and electrical frequency are proportional:

1. Go back to the main screen and search for the letter F.
   1. Change the frequency by pressing enter and then manipulating the value using the up and down arrows.
   2. Use the > (right arrow/reset) button to change between the column of values.
   3. Enact any changes by pressing enter.
   4. Cancel changes and continue to run at the present frequency by pressing "Esc."

8. Set the frequency to 10 Hz.

1. Press the green "Run" button.
2. Scroll to the voltage, current, and frequency readings and record their values.
3. Repeat for the following frequencies: 25, 45, 60, and 70 Hz.
4. Note that a maximum frequency limit might have been set to prevent the user from exceeding 60 Hz, so adjust the maximum frequency limit from the "E2" menu.

9. Note that if the drive overloads or faults: Press the red "Stop" button, and then press the > (right arrow/reset) button.

Table 1: Main VFD Settings