TABLE OF CONTENTS Most pipeline facilities use electrical equipment of some sort or another, ranging from simple power circuits of a few amperes capacity to sophisticated supervisory control and data acquisition systems. It is beyond the scope of this manual to provide a complete section on electrical information for pipeline facilities. This section is intended to provide some basic data that will prove useful to field personnel responsible for electrical installations.
Based on known facts and calculations, the best selection is made after a close study of the installation, operation, and servicing of the motor. Basic steps in proper selection are numbered 1 through 8 and are briefly described.
Power supply
Voltage-NEMA has recommended the following standards.
| Nominal Power System Volts | Motor Nameplate Volts |
|---|---|
| 240 | 230 |
| 480 | 460 |
| 600 | 575 |
Frequency Motors rated 200 horsepower or less can vary not to exceed 5% above or below its rated frequency.
Phases Three phase power supplies are found in most industrial locations; for most residential and rural areas, only single phase power is available.
HP and duty requirements
Continuous duty means constant load for an indefinite period (about 90% of all motor applications).
Intermittent duty means alternate periods of load and no load, or load and rest.
Varying duty means both the load and time operation vary to a wide degree.
Speeds Single speed motors are the most common, but when a range of speeds is required multispeed motors will give two, three, or four fixed speeds.
Service factors Open, general purpose motors have a service factor...
