RING-RETAINER 8U5694 - Caterpillar

Illustration 2 g02450580
System bypass mode power flow automatic voltage regulation (AVR) mode Offline Modes
When an MMU is offline, there is no power flow through the MMU. The contactors are open, and the line static switch and utility inverter are off. Since other MMUs are online, the bypass breaker is open.AVR (Automatic Voltage Regulation) Mode
The AVR mode is an operating mode where output voltage is regulated to the nominal setpoint. The power factor and harmonic benefits of the UPS are also still present in this mode. However, the load is not protected when the system is in AVR mode.AVR mode can be entered by one of the following reasons:
System Start-upWhen the UPS is transitioning from bypass to online, the UPS transfers from bypass to AVR mode. Then the UPS begins to motor (or preheat) the flywheels. The UPS will remain in AVR mode until there are enough flywheels above 4000 RPM to support the load connected to the UPS output.
Flywheel ErrorsThere are not enough flywheels available to support the load connected to the UPS output.
Auto StartThe system remains in the AVR Mode until the system is charged and sustain discharge. During the AVR Auto Start state, the flywheel must achieve a rate of 45 RPM before changing to the AVR Charging state.
ChargingThe system enters this state when the UPS starts to charge the flywheel. When the flywheel has achieved nominal speed, the system enters the Online Stand-by state. Normally, the system enters the Online Charging state when the flywheel reaches 4000 RPM.
Verify SignalsWhen the system is in this state, the UPS verifies that the correct system telemetry is present. This state is used:
When you are starting the system
During the recovery of flywheel errorsDischarge Mode
The system enters this state when the unit is supplying power to the load from the flywheel. The system automatically enters this state when utility power is disrupted.The input contactor is open, the static switch is off, and power is flowing out of the flywheel (MMU) cabinets. The flywheel inverters regulate the voltage on the DC bus. The utility inverter converts the DC bus voltage to 3-phase AC voltage, which is supplied to the load.Discharge
The UPS has disconnected from the input and is delivering power to the load from the flywheel.There are four reasons that the flywheels will go into discharge.
RMS Voltage High or LowIf the RMS voltage goes high or low by a certain percentage, the UPS will discharge and a message will appear in the log file.Note: The percentage of voltage change is defined by adjustable operating parameters that are specified by the user.
Fast Voltage TransientThe UPS is constantly monitoring the voltage coming from the utility, on the order of once every 52 microseconds. If the voltage spikes above or below a certain range, the flywheels will discharge to correct the voltage. The range is specified by the user. A message is sent to the log file if the voltage spikes above or below the specified range. Fast voltage transient is the most common reason