3. Insert the load cables through the protective sleeve. Attach the cables to their respective load terminals, one cable to each terminal, by inserting the cable in the terminal slot and tightening the terminal nut with the wrench that was clipped to the transparent cover. Install the wrench on the cover and install the cover.
4. Tighten the drawstring on the protective sleeve to prevent the entry of foreign matter through the hole around the cable.
You may convert the voltage at the load terminals to 120/208 volts or 240/416 volts by properly positioning the voltage change board (fig. 3-9). The board is located directly above the load terminal board.
The procedure for positioning the voltage change board for the required output voltage is as follows:
1. Disconnect the transparent cover by loosening the six quick-release fasteners.
2. Remove the 12 nuts from the board. Move the change board up or down to align the change board arrow with the required voltage arrow. Tighten the 12 nuts to secure the board.
3. Position and secure the transparent cover with the six quick-release fasteners and close the access door.
The phase sequence indicator is a device used to compare the phase sequence of three-phase generators or motors. Examples of its use are as follows: to
Figure 3-9. - Voltage change board.
compare the phase rotation of an incoming alternator that is to be operated in parallel with an alternator already on the line or to determine the phase rotation of motors being put into use for the first time.
One type of phase sequence indicator is a tiny three- phase induction motor. The three leads of the motor are labeled "A," "B," and "C," as shown in figure 3-10. The insulating hoods over the clips are of different colors: red for A, white for B, and blue for C.
The rotor in the instrument can be observed through the three ports as it turns so that you can note the direction in which it rotates. The rotor can be started by means of a momentary contact switch: it, stops again when you release the switch.
You also may use a solid-state phase sequence indicator with two lights. Whichever light is on indicates the phase sequence of the voltage in the conductors that the instrument is connected to; for example, the light labeled "ABC" indicates one phase sequence, while the other light, labeled "BAC," indicates another. If you are working with three-phase conductors (all of the same color) that are installed but not labeled, you may connect the phase sequence indicator to the three conductors, turn on the power, check the phase sequence of the conductors as connected to the instrument, and turn off the power. You may then label the conductors with numbers, letters, or colored marking tape.
You also may check the phase sequence of an incoming alternator before paralleling it with an operating load-side alternator. Connections must be made so that the phase sequence of the two generators will be the same.
Figure 3-10. - Phase sequence indicator.Continue Reading