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| Illustration 1 | g03693347 |
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Utility inverter module (1) Utility gate driver board | |
The utility inverter assembly is located in the upper part of the flywheel cabinet on the left. There are two inverters in the system, the flywheel inverter and the utility inverter. The inverters are used for the following reasons:
- Develop the current that is necessary to rotate the flywheel
- Develop the voltage that is used during a discharge
- Charge and maintain the DC bus voltage
Power is provided by one inverter at a time to the DC bus. The utility inverter maintains the voltages for the DC bus. The utility inverter regulates the output voltage and maintains the DC bus when the system is online or charging. The utility inverter contains a three-phase full wave insulated gate bipolar transistors (IGBT). The insulated gate bipolar transistors perform the following function:
- Rectify the AC voltage from the filter node
- Convert the DC voltage back to AC voltage during discharge
The phase-A module must be removed in order to access the phase-B module. In order to access the phase-C module, the phase-A module and the phase-B module must be removed.
- Refer to Systems Operation, Test and Adjust, UENR4695, "Internal Component Pre-Removal Steps FPU Cabinet". Perform the internal component pre-removal procedure to shut down the system and to gain access to internal components.
Note: The flywheel cabinet must be de-energized before removal steps can be performed.
- Disconnect the inductor input cable from the left side of the utility inverter module.
- Disconnect J1, J3, and J25.
- Remove the six mounting bolts that connect the bottom of utility inverter module to the flywheel cabinet frame.
- Remove the eight mounting bolts that connect the bottom of utility inverter module to flywheel cabinet frame.
- Install the DC capacitor/inverter module lifting device.
- Slide the module forward and down to remove the assembly.
Note: The utility inverter module weighs
25.4 kg (56 lb) . Exercise caution when removing the last bolt so the assembly does not fall and damage components or personnel.
- Install the DC capacitor/inverter module lifting device on the new module.
- Move the new module into the correct location.
- Install the six mounting bolts that connect the bottom of module to the flywheel cabinet frame.
- Install the eight mounting bolts connecting top of module to flywheel cabinet frame.
- Connect J1, J3, and J25.
- Ensure that the installation is correct and complete.
- Energize the system according to the system start-up section. Refer to Systems Operation, Test and Adjust, UENR4695, "System Startup".