Article 455 Phase Converters
Manufactured Phase. This definition shall apply within this article and throughout the Code.
The phase that originates at the phase converter and is not solidly connected to either of the single-phase input conductors.
Phase Converter. This definition shall apply within this article and throughout the Code.
An electrical device that converts single-phase power to 3-phase electric power.
Informational Note: Phase converters have characteristics that modify the starting torque and locked-rotor current of motors served, and consideration is required in selecting a phase converter for a specific load.
Rotary-Phase Converter. This definition shall apply only within this article.
A device that consists of a rotary transformer and capacitor panel(s) that permits the operation of 3-phase loads from a single-phase supply.
Static-Phase Converter. This definition shall apply only within this article.
A device without rotating parts, sized for a given 3-phase load to permit operation from a single-phase supply.
Informational Note: Single-phase conductors sized to prevent a voltage drop not exceeding 3 percent from the source of supply to the phase converter may help ensure proper starting and operation of motor loads.
- Nonmotor loads
- The 3-phase, locked-rotor current of the largest motor as determined from Table 430.251(B)
- The full-load current of all other 3-phase motors operating at the same time
Informational Note: Magnetic motor starters, magnetic contactors, and similar devices, with manual or time delay restarting for the load, provide restarting after power interruption.