## Determine the V/H ratio when frequency changes and the voltage is constant.

List the reasons for using AC drives to control the speed of AC motors.Explain the methods of controlling the speed of an AC motor and identify which one is most effective. Describe the purpose of the following sections of an AC drive:

Operator Control               Drive Controller                         AC Motor

Explain the differences among volts/Hz, AC closed-loop vector, and sensorless vector control methods. Describe the operation of the following major sections of the VAC drive:

Converter     Intermediate               Circuit Inverter

Determine the V/H ratio when frequency changes and the voltage is constant.Describe the operation of the flux vector drive.

### design suitable bearings to support the load for at least 5E8 cycles at 1 200 rpm using deepgroove ball bearings.

The shaft shown in Figure P11-4 was designed in Problem 10-19. For the data in row (a) of Table P11-1, and the corresponding diameter of shaft found in Problem 10-19,….

### Find the minimum film thickness for a long bearing with the following data: 30-mm dia, 130 mm long, 0.0015 clearance ratio, 1 500 rpm, ISO VG 100 oil at 200°F, and supporting a load of 7 kN.

1.       A paper machine processes rolls of paper having a density of 984 kg/m3. The paper roll is 1.50-m OD X 22-cm ID X 3.23-m long and is on a simply supported, 22-cm OD, steel….

### Find the minimum film thickness for a bearing with these data: 30-mm dia, 25 mm long, 0.0015 clearance ratio, 1 500 rpm, ON = 30, ISO VG 220 oil at 200°F.

1.       Problem 7-12 estimated the volume of adhesive wear to expect from a steel shaft of 40 mm dia rotating at 250 rpm for 10 years in a plain bronze….