NRU Diode Replacement

Transcription

1 REPLACEMENT KIT INSTRUCTIONS NRU Diode Replacement Contents What This Kit Contains This publication describes how to replace a diode in non-regenerative front-end units. Using the table below, verify that you have received the appropriate items in your kit: For this part: You should receive this quantity: diode 2 bottle of silicone oil 1 Other Items Needed Before you begin, be sure you also have the following: Whatever tool(s) you will need to: Remove, loosen, and tighten bolts Remove, loosen, and tighten nuts Apply silicone oil onto the pole faces of the diode Documentation: Your drive system schematics Publication 2364E-5.01, Non-Regenerative DC Bus Supply (NRU) User Manual

2 2 NRU Diode Replacement Safety Precautions The following general precautions apply to NRUs and their respective drive systems:! ATTENTION: Only those familiar with the drive system, the products used in the system, and the associated machinery should plan or implement the installation, startup, and future maintenance of the system. Failure to comply can result in personal injury and/or equipment damage. ATTENTION: Verify that all sources of AC and DC power are deenergized and locked out or tagged out in accordance with the requirements of ANSI/NFPA 70E, Part II. ATTENTION: The system may contain stored energy devices. To avoid the hazard of electrical shock, verify that all voltage on capacitors has been discharged before attempting to service, repair, or remove a drive system or its components. You should only attempt the procedures in this manual if you are qualified to do so and are familiar with solid-state control equipment and the safety procedures in publication NFPA 70E. ATTENTION: When servicing any unit, do not drop any nuts, bolts, washers, etc. inside the unit as they may cause a short circuit on power up. Dropped items must be found and removed before you apply power. ATTENTION: This drive system contains ESD (Electrostatic Discharge) sensitive parts and assemblies. Static control precautions are required when installing, testing, or repairing this assembly. Component damage can result if ESD control procedures are not followed. If you are not familiar with static control procedures, refer to Rockwell Automation publication , Guarding Against Electrostatic Damage or any other applicable ESD protection handbook. Special Instructions The following special instructions apply to NRUs and their respective drive systems: Important: As you remove parts, place them in order on a clean surface because you will need to reuse some of them during reassembly. Important: Some washers, such as the diode clamp washers and the Belleville washers used on busbar bolts have only one correct orientation.

3 NRU Diode Replacement 3 Removing the Diode This section contains the procedure for removing a diode. 1. Remove the Lexan guard covering the circuit breaker and fuses in the left bay. 2. Remove the Lexan guard covering the diode bridge assembly in the right bay. 3. Remove the 4 bolts that hold the horizontal AC busbar to the fuse busbar in the left bay. 4. While supporting the busbar, remove the nuts that hold the horizontal AC busbar to the heatsinks in the right bay from right to left. Note: Removing the nuts/bolts in the right bay from right to left helps balance the busbar when removing the last bolt. 5. Remove the busbar. 6. If your NRU is rated at: 2500A DC or 3000A DC Then: Remove the piece of Lexan that covers the heatsinks. 7. Note the position of the force gage and force number on the edge of the diode clamp bar of the diode to be changed. 8. Remove the diode clamp nuts of the diode to be changed, while holding and preventing the heatsink from falling forward. 9. Remove the AC heatsink. Important: Be careful when servicing the 1500A DC and 2000A DC NRUs so that the diode does not fall out. Once the diode is unclamped, the only thing that holds the diode to the heatsink is the silicone oil.

4 4 NRU Diode Replacement 10. If your NRU is rated at: Then: 2500A DC or 3000A DC 1. Remove the diode along with its Lexan holder. 2. Remove the Lexan holder from the diode, as shown in Figure 1. Otherwise Remove the diode. Figure 1 Removing the Lexan Holder from the Diode Note: Before installing a diode, verify that the surfaces of the heatsink do not have any burrs or sharp edges that may scratch the pole faces of the diode. Polish heatsink surfaces as needed.

5 NRU Diode Replacement 5 Installing A Diode 1. Verify that the diode is of the correct rating: NRU Output Current (A DC) Diode Rating 180 / A, 1800V A, 1800V 1500 / A, 1800V A, 1800V A, 1800V 2. If your NRU is rated at: 2500A DC or 3000A DC Then: Put the Lexan holder on the diode. 3. Apply two or three drops of silicone heatsink oil to each side of the diode. Spread the oil evenly over the pole face of the diode. 4. Install the diode (with the correct polarity) onto the centering roll pin on the back heatsink. Refer to Figure 2 for diode polarity information. Refer to Table A and Figure 3 for installation polarity. Important: Be careful not to scratch diode pole faces when installing diode onto the centering roll pin. Figure 2 Diode Polarity Details + (Anode) Table A Installation Polarity - (Cathode) HS1 (-): Left Heatsink Diode Symbol Diode Pole Facing Front of MCC HS2 (+): Right Heatsink Diode Symbol Diode Pole Facing Front of MCC D1 - (Cathode) D2 + (Anode) D3 - (Cathode) D4 + (Anode) D5 - (Cathode) D6 + (Anode)

6 6 NRU Diode Replacement Figure 3 Illustration Showing Diode Installation Polarity TOP VIEW (Back) (Front) LEFT VIEW RIGHT VIEW D1 D2 D3 D4 (Back) (Front) (Front) (Back) D5 D6 Note: The heatsink assembly shown in Figure 3 is the design for the 180, 350, and 900A DC NRUs. The same diode location and installation polarity is also typical in the other NRU ratings.

7 NRU Diode Replacement 7 5. Carefully install the AC heatsink over the diode clamp bolts and snug it up to the diode pole face. 6. Replace the diode clamp nuts and washers and start them by hand to secure the front heatsink. Important: Verify that the diode clamp washers are installed correctly with the flat side toward the nut and the rounded side toward the clamp/heatsink. 7. Check that the back roll pin is properly positioned on the back heatsink and the front roll on the front heatsink, using a small mirror. Note: A roll pin is properly positioned if it is centered on the diode pole face and the heatsink is flat against the diode pole face. 8. Once the roll pins drop into place, tighten the diode clamp nuts by hand until snug, while maintaining the position of the front heatsink. If: A small mirror is not available or if the roll pins are not properly positioned Then: 1. Grasp the front heatsink with both hands. 2. Attempt to slide the front heatsink up and down, left and right. Note: If the roll pins are in place the AC heatsink will not move with respect to the DC heatsink. If the roll pins are not in place, the AC heatsink will tend to tip and slide in any direction. 9. Once the roll pins drop into place, tighten the diode clamp nuts by hand until snug, while maintaining the position of the front heatsink. 10. If your NRU output current (A DC) is: 3. Move the AC heatsink around until the roll pins drop into place. Important: Use only light force to avoid scratching the diode pole face. Tighten the diode clamp nuts evenly, 1/4 turn at a time until the diode clamp gauge reads: 180 / lbs. per leaf of gauge kilo-lb on gauge 1500 / kilo-lb on gauge 2500 / kilo-lb on gauge

8 11. If your NRU is rated at: 2500A DC or 3000A DC Then: Install the Lexan guard against the heatsink. 12. Install the AC horizontal busbar. 13. If your NRU output current (A DC) Torque busbar bolts to: 180 / lb-ft lb-ft 1500 / lb-ft (if bolt size is 5/16 ) 25 lb-ft (if bolt size is 3/8 ) 2500 / lb-ft 14. Using a continuity testing device, verify that shorts do not exist between: any of the 3 AC horizontal busbars and PE any of the 3 AC horizontal busbars 15. Install the Lexan guard that covers the circuit breaker in the left bay. 16. Install the Lexan guard that covers the diode bridge assembly in the right bay. 17. Dispose of the removed part according to your company s procedures and local ordinances. NRU is a trademark of Rockwell International or its subsidiaries. Lexan is a trademark of General Electric Corp. Supersedes Publication 2364E February 1997 P/N Rockwell International. All Rights Reserved. Printed in USA