- Uninterruptible Power Supply:
- ES12F (S/N: CZE1-UP)
- UPS 1000S (S/N: CZS1-UP)
- UPS 1000Z (S/N: EDZ1-UP)
- UPS 120 (S/N: CNK1-UP)
- UPS 1200S (S/N: CZT1-UP)
- UPS 1200Z (S/N: HDR1-UP)
- UPS 150 (S/N: CPC1-UP)
- UPS 250 (S/N: BEE1-UP; CNM1-UP; APZ1-UP)
- UPS 300 (S/N: CNJ1-UP)
- UPS 301 (S/N: CSY1-UP)
- UPS 500 (S/N: CSE1-UP)
- UPS 600 (S/N: CTX1-UP)
- UPS 750 (S/N: CPM1-UP)
- UPS 900 (S/N: CRY1-UP)
- UPS500G (S/N: TYD1-UP)
- UPS600G (S/N: DLD1-UP)
- UPS 1000S (S/N: CZS1-UP)
Introduction
This Special Instruction provides the necessary information on diode test procedure to determine the failed Active Power Module (APM) Inverter.
Do not perform any procedure in this Special Instruction until you have read this entire Special Instruction and you understand this information.
Important Safety Information
Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs.
A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools in order to perform these functions properly.
Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard.
Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. Ensure that any tool, procedure, work method, or operating technique you use that is not recommended by Caterpillar is safe.
Ensure that the product will not be damaged or the product will be made unsafe by the operation, lubrication, maintenance, or the repair procedures that are used.
Do not operate or work on this machine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact your Caterpillar dealer for replacement manuals. Proper care is your responsibility. |
Personal injury or death can result from improper assembly procedures. Do not attempt any assembly until you have read and understand the assembly instructions. |
This system must be installed with a disconnect switch that is supplied by the customer and has been rated for the output power. An additional service disconnect device must be installed for the input power when the device is required by local regulations and/or national regulations. |
Power source must be disconnected before working on equipment. Failure to disconnect power source could result in injury or death. |
High voltage may be present. The power source must be disconnected before working on the equipment. Failure to disconnect the power source could result in injury or death. Verify that the equipment is not energized before performing any maintenance. This work must be performed by trained personnel with correct tools and procedures. |
Personal injury or death can result from high voltage. Moisture can create paths of electrical conductivity. Make sure that the electrical system is OFF. Lock out the starting controls and tag the controls "DO NOT OPERATE". |
Purpose
The purpose of diode testing the inverter (APM) is listed below:
- Firmware version 5.12 or greater has logic that will lockout an MMU if an inverter (APM) error occurs.
- The lock-out logic will only prevent an MMU from restarting after an inverter error, it will not prevent inverter failures. In some cases the inverter fails "lightly" and then fails more "violently" after the MMU is restarted.
- Prior to firmware version 5.12, the logic restarts the MMU automatically when the inverter (APM) error clears and the "violent" failure takes the UPS to bypass. In response to this type of failure, the controller will no longer reset any inverter faults.
- Any inverter (APM) fault will require a service technician to perform checks on the MMU and potentially replace the inverter before issuing a service-level password command to restart the MMU.
Instructions for Testing An Inverter (APM)
Obtain and review the log file to identify the following conditions:
- If the error occurred when the MMU is in stand-by, replace the APM.
- If the UPS transferred to bypass due to the error but not due to an overload, replace the APM.
- If there are blown inverter or static bypass fuses, replace the APM.
Instructions for Performing Diode Testing
Perform the following Instructions for diode testing the Installed Inverter:
- Lockout the MMU through the MMU isolation switches or the MMU input and output breakers prior to working in the MMU cabinet.
- Confirm that the DC bus has no voltage. Disconnect the gray Armature connector on the bottom of the flywheel cabinet and wait for the DC bus voltage to come down.
- If there is visible damage to an APM, remove the damaged APM and diode check any of the non-damaged APMs out of the cabinet.
Diode check readings may vary depending on the meter and/or flywheel cabinet but the diode readings from each IGBT should be similar for each inverter. Refer to Table 1 for expected values.
The basic goal of this test is to measure the two states (forward bias and reverse bias) of each diode.
Show/hide tableTable 1 Expected Values         Positive Lead at + DC Bus     Negative Lead at + DC Bus     Positive Lead at - DC Bus     Negative Lead at - DC Bus     A Phase     > 0.3 VDC and Charging     ~ 0.3 VDC     ~ 0.3 VDC     > 0.3 VDC and Charging     B Phase     > 0.3 VDC and Charging     ~ 0.3 VDC     ~ 0.3 VDC     > 0.3 VDC and Charging     C Phase     > 0.3 VDC and Charging     ~ 0.3 VDC     ~ 0.3 VDC     > 0.3 VDC and Charging     Show/hide tableTable 2 Recorded Values for Utility Inverter         Positive Lead at + DC Bus     Negative Lead at + DC Bus     Positive Lead at - DC Bus     Negative Lead at - DC Bus     A Phase                     B Phase                     C Phase                    
- Connect the positive meter lead (1) to the positive DC bus connection (2). Refer to Illustration 1.
Illustration 1 | g03393437 |
(1) Positive meter lead (2) Positive DC bus connection |
- Connect the negative meter lead (3) to the ØA connection of the utility inverter. Record the reading in Table 2.
Illustration 2 | g03393440 |
(3) Negative meter lead |
- Connect the negative meter lead (3) to the ØB connection, then to the ØC connection. Record the readings in Table 2.
- Connect the negative meter lead (3) to the positive DC bus connection (2). Refer to Illustration 3.
Illustration 3 | g03393441 |
(2) Positive DC bus connection (3) Negative meter lead |
- Connect the positive meter lead (1) to the ØA connection of the utility inverter. Record the reading in Table 2.
Illustration 4 | g03393442 |
(1) Positive meter lead |
- Connect the positive meter lead (1) to the ØB connection, then to the ØC connection. Record the readings in Table 2.
- Connect the positive meter lead (1) to the negative DC bus connection (4). Refer to Illustration 5.
Illustration 5 | g03393444 |
(1) Positive meter lead (4) Negative DC bus connection |
- Connect the negative meter lead (3) to the ØA connection of the utility inverter. Record the reading in Table 2.
Illustration 6 | g03393440 |
(3) Negative meter lead |
- Connect the negative meter lead (3) to the ØB connection, then to the ØC connection. Record the readings in Table 2.
- Connect the negative meter lead (3) to the negative DC bus connection (4). Refer to Illustration 7.
Illustration 7 | g03393447 |
(3) Negative meter lead (4) Negative DC bus connection |
- Connect the positive meter lead (1) to the ØA connection of the utility inverter. Record the reading in Table 2.
Illustration 8 | g03393442 |
(1) Positive meter lead |
- Connect the positive meter lead (1) to the ØB connection, then to the ØC connection. Record the readings in Table 2.
- Connect the positive meter lead (1) to the positive DC bus connection (2).
Show/hide table
Table 3 Recorded Values for Flywheel Inverter         Positive Lead at + DC Bus     Negative Lead at + DC Bus     Positive Lead at - DC Bus     Negative Lead at - DC Bus     A Phase                     B Phase                     C Phase                    
Illustration 9 | g03393437 |
(1) Positive meter lead (2) Positive DC bus connection |
- Under the flywheel rotor, disconnect the gray Anderson connector (5). Connect the negative meter lead (3) to the ØA connection at the Anderson connector (5). Record the reading in Table 3.
Illustration 10 | g03393450 |
(3) Negative meter lead (5) Gray Anderson connector |
- Connect the negative meter lead (3) to the ØB connection, then to the ØC connection. Record the readings in Table 3.
- Connect the negative meter lead (3) to the positive DC bus connection (2) .
Illustration 11 | g03393441 |
(2) Positive DC bus connection (3) Negative meter lead |
- Connect the positive meter lead (1) to the ØA connection at the Anderson connector (5). Record the reading in Table 3.
Illustration 12 | g03393452 |
(1) Positive meter lead (5) Gray Anderson connector |
- Connect the positive meter lead (1) to the ØB connection, then to the ØC connection. Record the readings in Table 3.
- Connect the positive meter lead (1) to the negative DC bus connection (4) .
Illustration 13 | g03393444 |
(1) Positive meter lead (4) Negative DC bus connection |
- Connect the negative meter lead (3) to the ØA connection at the Anderson connector (5). Record the reading in Table 3.
Illustration 14 | g03393450 |
(3) Negative meter lead (5) Gray Anderson connector |
- Connect the negative meter lead (3) to the ØB connection, then to the ØC connection. Record the readings in Table 3.
- Connect the negative meter lead (3) to the negative DC bus connection (4) .
Illustration 15 | g03393447 |
(3) Negative meter lead (4) Negative DC bus connection |
- Connect the positive meter lead (1) to the ØA connection at the Anderson connector (5). Record the reading in Table 3.
Illustration 16 | g03393452 |
(1) Positive meter lead (5) Gray Anderson connector |
- Connect the positive meter lead (1) to the ØB connection, then to the ØC connection. Record the readings in Table 3.
- Reconnect the gray Anderson connector (5) under the flywheel rotor.
- Review the recorded readings for the diode checks.
Note: Failed inverter IGBT's will typically read 0.0 VDC. Failed inverters in the cabinet may affect the readings of the other inverters.
- When a failed or suspect failed inverter is detected, it is beneficial to remove the remaining inverters on the flywheel/utility side that contains the failed inverter and retest them each individually.
- After repairs are made, repeat the diode checks. If no shorts are questionable reading, apply power back to the MMU.
- Enter the SERVICE level password into UPSView.
- Enter "Command" function: "Group 5: APM IGBT LOCKOUT", to clear the lockout function.