The UPS functions automatically in order to supply AC electrical power to the critical load. There are several operation modes that allow the UPS to accomplish this task. Most of the operating modes have several states that occur in that mode. The mode and the state are displayed on the LCD display. The LCD display is located on the front panel. The operating modes are listed below:
- On-line Modes
- Discharge Modes
- Bypass Modes
- Automatic Voltage Regulation Mode
- Shutdown Mode
- Manual Mode
- Calibration Mode
The UPS continually monitors internal systems and the incoming utility power. The UPS automatically toggles between the modes that are listed above, and without intervention by an operator. The detection logic and the switching logic that is programmed into the UPS ensures that operating mode changes are automatic. The detection logic and the switching logic that is programmed into the UPS ensures that operating mode changes are transparent to the critical load.
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| Illustration 1 | g01254179 |
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Diagram of On-line Mode | |
On-line mode is the standard operating mode for the system. When the system is in this mode, the load is protected. The system is able to discharge in order to support the load.
The UPS is providing a constant voltage to the load. The UPS is drawing power from the input in order to spin the flywheels up to the speed for charging (4000 RPM). The UPS regulates voltage. When the flywheel reaches 4000 RPM, the UPS can discharge.
The system enters this state when the flywheel reaches 4000 RPM. The system is charging in this state. The system can sustain discharge in this state.
When the speed of the flywheel reaches 7700 RPM, the system is in the "On-line" standby state. 7700 RPM is rated idle speed for the flywheel.
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| Illustration 2 | g01254181 |
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Diagram of Discharge Mode | |
The system is in this state when the unit is supplying power to the load. If there is a disruption in power, the system will change to this state. There are four reasons that the flywheels will go into discharge.
RMS Voltage (High or Low) - The UPS will discharge if the RMS voltage goes high by a certain percentage of the operating parameters that have been set. The UPS will discharge if the RMS voltage goes low by a certain percentage of the operating parameters that have been set. The the operating parameters are specified and adjustable by the user. A message will appear in the log file.
Fast Voltage Transient - For every 52 microsecond cycle, the UPS monitors the voltage that originates from the utility. If the voltage that is specified by the user exceeds a certain range the flywheels will discharge in order to correct the voltage. If the voltage that is specified by the user drops below a certain range, the flywheels will discharge in order to correct the voltage. A message is sent to the log file.
Frequency (High or Low) - The UPS is constantly monitoring the frequency of the utility power. If the UPS determines that the frequency is out of the specified range of the user, the flywheels will discharge in order to correct the frequency. A message will appear in the log file.
DC Bus Voltage (High or Low) - The utility inverter keeps AC voltage at 480 VAC. The utility inverter keeps DC voltage at 750 DCV. If an input disturbance occurs or a large increase occurs, the phase load will be changed. Also, the DC Bus will go up or the DC Bus will go down.
The UPS is still delivering power to the load. The UPS has qualified the input voltage. Additionally, the UPS will match the output (frequency and phase) to the input source.
Once a phase match is achieved, the UPS connects to the source. Then, the UPS transfers the load from the flywheel to the source. The Uninterruptible Power Supply initiates the on-line state (motoring state) upon completion of the "walk in" state.
Self-Discharge (Service Mode Only)
This state stops the flywheel electrically. This state is used for the following:
- Prepare the system to be moved.
- Secure the system for maintenance.
- The On-line Self Discharge Mode can be entered once in a 24 hour time period. The system will not go into this state automatically.
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| Illustration 3 | g01254176 |
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Diagram of Bypass Mode | |
The bypass circuit powers the critical bus for one of the following reasons:
- Maintenance is required.
- The UPS cannot maintain voltage to the load due to an overload that was sustained or a malfunction that occurred.
The bypass circuit also provides a path for power from an alternate AC source. The control system of the UPS constantly monitors the availability of the system bypass circuit in order to perform a transfer. The system bypass circuit consists of the following components:
- Static Bypass Switch
- Output Contactor
- Circuit Breaker (System Bypass)
Note: The Static Bypass Switch is an option.
The output contactor isolates the module outputs of the UPS. The Circuit Breaker (System Bypass) works in parallel with the optional static bypass switch. The static bypass switch is a solid-state device that can connect the alternate AC source to the load instantly.
Bypass mode directly connects the incoming utility to the system load. When the system is in the bypass mode, the load is not protected. The load can be affected by a disruption of incoming power. The Bypass mode is entered by one of the following events:
- Start-up
- The Keyswitch (Manual)
- Failure to Recover From a Fault
Repeated errors that cause the system to oscillate between the bypass mode and On-line mode can lock the system into the bypass mode. When the system is locked in the bypass mode, the user must change the mode of the system. Use the keyswitch in order to change the mode of the system.
Bypassed Off-line - When the system has been locked into bypass mode because of a fault condition, the system enters the Bypass off-line state. Power is going through the bypass circuit. The system can leave the Bypass off-line state only when the system is commanded by the UPSView software for monitoring or by the keyswitch.
"Bypassed-Verify" Signals - When the system is in this state, the system verifies that the correct system telemetry is present. This state is used when you are starting the system and the state is used during the recovery of errors.
"Bypassed-Auto Start" - Bypassed-Auto Start is the default state at start-up. The system cannot immediately protect the load after the system is started. During the normal operation, the system will enter Automatic Voltage Regulation mode.
Automatic Voltage Regulation Mode
The Automatic Voltage Regulation Mode can be entered by one of the following events:
- Start-up
- Error (Flywheel)
Automatic Voltage Regulation Auto Start State
The system remains in the Automatic Voltage Regulation Mode until the system is charged and until the system is able to sustain discharge. During the Automatic Voltage Regulation Auto Start State, the flywheel must achieve a rate of 45 RPM before changing to the Automatic Voltage Regulation Charging state.
Automatic Voltage Regulation Charging
The system enters this state when the system starts to charge the flywheel. When the speed of the flywheel is greater than 7700 RPM, the system enters the On-line Standby state. Normally, the system enters the On-line Charging state when the flywheel reaches 4000 RPM.
Automatic Voltage Regulation Verify Signals
When the system is in this state, the system verifies that the correct system telemetry is present. This state is used when you are starting the system and the state is used during the recovery of flywheel errors.
When the system is in the Shutdown mode, the following occurs:
- There is no power flow through the system.
- The system is shut down.
- No power is supplied to the load.
All contactors are open, and both static switches and utility inverters are OFF.
Shutdown modes can be entered for any one of the following reasons:
- An Emergency Power Off (EPO) has occurred, caused by one of the following.
- The EPO button was pressed on the front of the control panel.
- A remote EPO button was pressed.
- There are internal conditions or external conditions that could lead to a system failure.
Intervention by the operator is required in order to put the system back to the on-line mode if the system is shut down. If an EPO has occurred for an MMS, there is a reset switch that is located behind the door on the system cabinet of an MMS. If an EPO has occurred for an SMS, a reset switch located in the flywheel cabinet of the SMS must be moved to the I position.
The EPO button is located on the front door of the system cabinet in an MMS and the Flywheel cabinet of an SMS. When you press the EPO button, the UPS enters the Shutdown mode. Shutdown mode opens the input circuit breaker and the shutdown mode removes power from the load.
Press either of the following buttons in order to activate an emergency shutdown:
- Emergency Power Off button
- Remote Emergency Power Off button
Note: The location of the Remote Emergency Power Off button can be determined by your project engineer.
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When the emergency power off switch is used, high voltage still remains in the system. |
The manual mode is to be used by service technicians. When the system is in the manual mode, a technician can conduct diagnostic tests of the subsystems. This mode is only accessible to qualified service personnel.
Calibration Mode is used in the factory during the initial calibration. Refer to the following list for the various Calibration modes:
"Calibration Point" - The system uses this state to calibrate a telemetry channel.
Energizing - The energizing state is used during sensor calibration. The energizing state energizes the flywheel. The flywheel spins at the rate of several hundred RPM.
Auto Adjusting - This state adjusts the commutation of the flywheel in order to maximize charging.