Job Sheet 1 Installing the Net Watt-Hour Meter

Transcription

1 Job Sheet 1 Installing the Net Watt-Hour Meter Net kwh Meter The Grid-Tie Training System optional net meter is a V AC, single-phase, two-wire, bidirectional triple element watt-hour (Wh) meter (Figure 1-1). The meter has been tested by CSA to the UL standard. The net meter electronic circuitry is mounted in a safety enclosure and coupled to a set of digital counters. The counters log the total energy in Wh that passes in either forward or reverse directions (Figure 1-2). The net meter is non-standard the utility grid electrical connection. The detected signals are then converted by the meter s circuitry into the displayed Wh measurements. The unit requires a small amount of power (approximately 2 W) to drive the display and monitoring circuits. Figure 1-1. Net Watt-Hour Meter. Figure 1-2. Enclosed Meter with Counters. Festo Didactic Inc

2 OBJECTIVES In this job, you will complete the mounting of the net watt-hour meter onto the grid-tie current transformer to complete the installation. EQUIPMENT REQUIRED Refer to the Equipment Utilization Chart in Appendix A to obtain the list of equipment required for this job. SAFETY PROCEDURES 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. Your sleeves are rolled up. WARNING:This job requires exposing and handling typically live receptacle connections. Unplug both sources of power entering the grid-tie trainer and the plug for the solar simulator or the grid-tie plug (green wire). Be sure both the AC disconnect and DC disconnect switches of the grid-tie trainer are in the Off position before starting this project. Instructor initials: Festo Didactic Inc

3 PROCEDURE Securing the Meter to the Trainer If the meter has already been secured to the grid-tie trainer, verify that it is properly mounted (Figure 1-3) and aligned at the top (Figure 1-11). Then, proceed to the section titled, Assembling the Conduit. If the meter has not been secured to the grid-tie trainer, proceed to Step 2. Using the supplied screws and channel spring nuts, loosely secure the meter to the side of the assembled grid-tie trainer (Figure 1-3). The meter must be secured to the end of the trainer near the main AC distribution panel. Evenly tighten the four mounting screws. Figure 1-3. Properly Mounted Watt-Hour Meter. Assembling the Conduit To create the conduit assembly, begin by opening the front cover of the net watt-hour meter enclosure by releasing the two side plastic latches (Figure 1-4). 4 Festo Didactic Inc

4 Side Plastic Latches Figure 1-4. Meter Enclosure Latches. Remove the single Phillips-head screw that secures the meter/counter fall. Remove the meter/counter assembly and screw, and place them in a safe location. Phillips-head Screw Figure 1-5. Meter with Cover Open. Remove the nut from one of the angled conduit connectors and insert it into the top of the enclosure with the output facing toward the main AC distribution panel (Figure 1-6). Replace the nut on the inside and handtighten. Festo Didactic Inc

5 Nut Figure 1-6. Inserting the Angle Connector. Remove the front AC distribution panel cover by removing the four Retaining screws Retaining screws Figure 1-7. Front Panel Retaining Screws. 6 Festo Didactic Inc

6 a screwdriver and possibly a light hammer, remove the 3 4 from the upper right corner of the main AC distribution panel ¾" Knock-out Figure 1-8. Main AC Distribution Panel with Knockout Removed. Remove the nut from the second of the angled conduit connectors and insert it into the top of the power panel with the output facing toward the inside and hand-tighten for now. Nut Figure 1-9. Main AC Distribution Panel with Angle Connector Installed. Festo Didactic Inc

7 bushing into each end of the supplied length of conduit (Figure 1-10). Figure Installing Anti-Short Bushings. Remove the cap of each angle conduit connector, and then align and conduit connector caps, but leave them loose for now. Figure Aligning Conduit. Once aligned, tighten the nut on each angle connector inserted in both the main AC distribution panel and enclosure. Leave the caps loose to prepare for wiring. Running the Wire lengths and strip the wire ends bare, leaving approximately 3 4 of an inch Select one wire of each color. Align the ends and loosely twist the wires into a twisted pair set (Figure 1-12). 8 Festo Didactic Inc

8 Figure Twisted Pair. Bend the white wire at each end of one twisted wire pair. This will help you identify the wire pair later (Figure 1-13). Figure Bent White Wire. Remove the two angle conduit connector caps and feed both twisted pair of wires through the conduit and connectors from the main power meter enclosure. Replace and tighten the angle connector end caps. Wiring the Net Watt-Hour Meter each counter, and strip and twist the conductors together. Route this paired connection to the left, passing through the opening to the front of the meter, and terminate at the screw labeled COMN (Figures 1-14 and Festo Didactic Inc

9 Route the remaining wire from the left counter to the left, passing through the opening to the front of the meter, and terminate at the screw Route the remaining wire from the right counter to the left, passing through the opening to the front of the meter, and terminate at the screw D-OUT COMN D-IN Figure Counter Wiring. two twisted pairs of wire to the front of the meter panel via the left side Twisted pairs of wire Figure Meter and Twisted Pairs. 10 Festo Didactic Inc

10 Replace the Phillips-head mounting screw to secure the meter. terminal labeled CT L1 Color and the white wire to the terminal labeled CT L1 WHITE (Figure 1-16). Straighten the bent white wire on the second twisted pair. Wire and tighten this twisted pair to the appropriate power input terminals: terminal labeled Neutral (Figure 1-16). Figure Meter with Wired Twisted Pairs. Straighten the wires and thread any excess length through the panel Preparing the Current Transformer NOTE: Festo Didactic Inc

11 Figure Current Transformer Wire. approximately 3 4 NOTE: To prevent coil damage, do not pull the wire at the base of the coil while stripping the wires. 3 4 inch Leaving approximately 4 inches (102 mm) extending from the coil, NOTE: If a dot is not present on the coil, the wires should exit the bottom of the coil. Figure Wire Wrapped Current Transformer. 12 Festo Didactic Inc

12 Installing the Current Transformer Figure Main AC Distribution Panel. Insert and tighten the AC load side of the current transformer (CT) coil source end of the coil wire to the 14-gauge hot wire you disconnected that connection with the larger supplied wire nut. Bend the AC load coil wire around the coil to complete a tenth turn, as shown in Figure NOTE: At this point in the procedure, there should be ten turns of #14 AWG wire wrapped around the current transformer in order to provide a measurement resolution of 1 Wh. AC Source AC Load Figure Current Transformer. Festo Didactic Inc

13 Figure Main Power Pane with CT Installed. NOTE: Your tie-wrap mount may appear slightly different in style and/or color than the one shown in Figure Figure Wire Wrap Mount. distribution panel, right behind the upper portion of the CT coil. Secure the coil to the mount using a tie wrap. Connecting the Current Transformer to the Net Watt-Hour Meter wires to the 22-gauge twisted pair coming from the net meter that does Secure the connections with the small wire nuts provided. 14 Festo Didactic Inc

14 resistance between CT coil connections CT L1 COLOR and CT L1 WHITE on the net watt-hour meter (Figure 1-23). You should get a value ohms) or a shorted value could indicate that the wrong twisted pair were wired and should be investigated. Figure CT Coil Connections. Connecting the Power Connections source side end of the current transformer s hand-wound wire (Figure 1-24). You will have to remove and then replace the larger wire nut to Large wire nut Figure Net Meter Power Connection. Festo Didactic Inc

15 Crimp the provided crimp pin connector onto the end of the bent 22-gauge white wire. Connect and secure the pin connector to the the wiring of the net watt-hour meter. Crimp pin Figure Net Meter Power Connection. Replace the main AC distribution panel cover and tighten the four securing screws. Close and latch the net watt-hour meter cover. You have completed the assembly and wiring of the net watt-hour meter. Do not disassemble your equipment. 16 Festo Didactic Inc

16 Procedure Questions 1. The net watt-hour meter provided with your trainer logs the total energy (in Wh) passed in the a. forward direction. b. reverse direction. c. Both A and B are correct. d. None of the above is correct. 2. True or false: The watt-hour meter requires 2 watts of power to drive the display and circuits. a. True b. False 3. twisted pair should be wired to the terminal labeled CT L1 COLOR and the white wire should be wired to the terminal labeled CT L1 WHITE. a. True b. False 4. Which of the following describes the appropriate wiring of the bent twisted pair? a. to the terminal labeled CT L1 WHITE. b. to the terminal labeled CT L1 COLOR. c. d. the terminal labeled Neutral. Festo Didactic Inc

17 True or false: There should be ten turns of #14 AWG wire wrapped around the current transformer in order to provide a measurement resolution of 1 Wh. a. True b. False Name: Date: Instructor approval: 18 Festo Didactic Inc