Job Sheet 6 Installing the Combiner Box The Combiner Box The combiner box used in this course can combine photovoltaic (PV) solar sub-array strings that are up to 150 V DC each and up to 120 A total. Using six circuit breakers, the combiner box can operate up to 900 V DC total. With the use of four touch-safe fuse holders mounted on a DIN rail, the combiner box can operate up to 600 V DC total. Each one of the four solar subarray strings is fused at 10 A separately and combined at the output of the box with a copper bus bar. A safety device called a DC lightning arrestor is also wired to the combined output. Figure 6-1. Combiner Box. Festo Didactic Inc. 88191-20 47
OBJECTIVES In this job, you will install the combiner box onto the trainer frame and wire it to the four DC voltage strings that are supplied with the solar array simulator. EQUIPMENT REQUIRED Refer to the Equipment Utilization Chart in Appendix A to obtain the list of equipment required for this job. SAFETY PROCEDURES Before proceeding with this job, complete the following checklist. You are wearing safety glasses. You are wearing safety shoes. You are not wearing anything that might get caught such as a tie, jewelry, or loose clothes. If your hair is long, tie it out of the way. The working area is clean and free of oil. Your sleeves are rolled up. Instructor initials: PROCEDURE Preparing the Combiner Box NOTE: It is easier to prepare the combiner box on the bench before mounting it to the frame. between the box and the cover (Figure 6-2A). Apply downward pressure to the cover to pop it from the top hinge on the left side. Repeat the process for the right side. Festo Didactic Inc. 88191-20 49
A B Figure 6-2. Cover and Dead Front Removal. NOTE: Work the screwdriver into the top-left corner by the hinge and pop the dead front panel (Figure 6-2B) out from the detent area. Repeat the process for the right side and put it aside for now. bus bar with four tabs. A B Figure 6-3. Hardware Bag and Contents. 50 Festo Didactic Inc. 88191-20
Position a square wire connector into the square indent in the bus bar so that the wire opening is facing in the same direction as the metal tabs. behind until they are smooth. Figure 6-4. Bezel. Pick up the dead front panel shown in Figure 6-5 and remove the six smooth. Figure 6-5. Removing the Knock Outs from the Dead Front Panel. Festo Didactic Inc. 88191-20 51
Align the bezel with the dead front with the notches facing upward (Figure 6-6). Snap the bezel into place in the opening of the dead front. Figure 6-6. Aligning the Bezel with the Dead Front. Look at the bottom of the combiner box. Notice the knock outs that will matches the four conduits exiting the top of the solar array simulator. NOTE: Refer to Appendix A to identify the parts needed to complete a job. Figure 6-7. PVC Fittings. Determine the knock out diameter that is needed and remove the appropriate sections, starting with the small inner diameter and working carefully break it out using a pair of pliers. 52 Festo Didactic Inc. 88191-20
Figure 6-8. Knock Outs. until it is tight (Figure 6-9). Figure 6-9. Securing the Straight Fittings. Repeat the process for the three other connectors. Festo Didactic Inc. 88191-20 53
Take another look at Figure 6-9. Notice the DC lightning arrestor on the bottom-left side of the box. You will now install this part. Begin by removing the appropriate knock out. Hold the lightning arrestor in your hand and thread the nut all the way up to its body. This will serve as a spacer to clear the cover when it is installed and closed. Feed the wires through the knock out hole and tighten it in place with a second nut. bottom-right side of the box. Mounting the Combiner Box Remove the locking nuts from one over each of the four strings on the simulator and down over the PVC tubing. face upward. With the help of your partner, thread each wire grouping from the simulator into the combiner box (Figure 6-10). Figure 6-10. Threading the Wire Groupings. 54 Festo Didactic Inc. 88191-20
Slide the box down the four sets of wires, but not onto the tubing. Locate the four bolts, lock washers, and spring nuts for mounting the them clockwise until they are in a vertical position. Slide them into the general area of the mounting holes in the box. to the frame with bolts (Figure 6-11). Figure 6-11. Mounting the Box. Pull the wiring down and out of your way for the next steps. Mounting the Fuse Holders Locate the four fuse holders and four 10-amp fuses shown in Figure 6-12. Festo Didactic Inc. 88191-20 55
Figure 6-12. Fuse Holders and Fuses. Hook a fuse holder on the top edge of the DIN rail inside the box. Lower it and snap it on the bottom edge of the DIN rail. NOTE: You may have a fuse holder with a spring-loaded lock on the bottom or a lock that pulls out to lock onto the din rail. Repeat this process for the remaining holders. Once you have all four fuse holders mounted and evenly spaced on the DIN rail, loosen the four top screws in the holders. Slide the tabs of the bus bar into the open contacts and tighten the four screws (Figure Figure 6-13. Mounted Fuse Holders. 56 Festo Didactic Inc. 88191-20
Wiring the Combiner Box Wire the box starting with all green (ground) wires. Begin with the green wire from the lightning arrestor. NOTE: When routing and terminating wires in the box, give yourself some extra wire length to allow for errors and to run wires neatly to their termination points. Take the green wire down against the bottom of the metal box and then up to a center contact of the ground bus bar on the right side of the box A B C Figure 6-14. Routing and Terminating Green, White, and Red Wires. Then, starting with string 1 on the left, neatly route the green wire and terminate it in the lowest position on the bus bar. Next, wire the white ( negative) wires. Start with the lightning arrestor, which has a black ( negative) wire in place of a white wire. Bring the black wire down against the bottom of the metal box and then up to a center contact of the isolated ( negative) bus bar on the left Festo Didactic Inc. 88191-20 57
Then, starting with string 1 on the left, neatly route the white wire and terminate it in the top position on the bus bar. Wire the red (+ positive) wires next, starting with the lightning arrestor. Bring the red wire down against the bottom of the metal box and then up Then, starting with string 1 on the left, neatly route the red wire and terminate it in the bottom contact of the fuse holder. Cut the PVC conduit and pull the three wires that will connect the combiner box to the DC disconnect switch. Use a tubing cutter or hacksaw to cut a 16 1 " length of PVC conduit. Use the wire reels on the holder that you mounted to the lower section of the frame to begin wiring this box. Tape the free ends of the 10 AWG white, red, and green wires together. Slide the 16 1 " length of conduit over the taped end of wire. right corner of the combiner box. in place (Figure 6-15). 58 Festo Didactic Inc. 88191-20
Figure 6-15. Pulling the Wires. Terminate the three wires that you pulled into the box, starting with the green wire (Figure 6-16). Figure 6-16. Terminating the Wires. Festo Didactic Inc. 88191-20 59
Bring the green wire down against the bottom of the metal box and then up to the bottom position on the bus bar. Terminate the white wire in the same manner. Bring the red wire down against the bottom of the metal box and then up to the square bus bar contact. Terminate it with the red wire from the lightning arrestor by twisting the two together. This completes the wiring of the combiner box. A B Figure 6-17. Replace the Dead Front and Combiner Box Cover. Line up the tabs on the bottom edge of the front panel with the slots in the bottom of the box. Then, snap the top two corners into place (Figure Line up the cover plate with the combiner box. Press the top two corners with a little force until the cover snaps in place and can hinge vertically and will stay open when slid into its slotted holes. 60 Festo Didactic Inc. 88191-20
Keep your equipment set up. Ask your instructor to check and approve your work. Name: Date: Instructor approval: Festo Didactic Inc. 88191-20 61