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12. Operating Modes
12.1 Static-Bypass (Stop operation)
During power up the UPS starts up in Bypass mode except when:
•
Performing cold start operation.
•
Performing frequency conversion.
•
When input and output voltages are unequal causing bypass to be disabled.
If the UPS unit is severely overloaded or develops an internal fault, power flow is automatically switched
from the unit's main circuit to the bypass circuit. Power flow through the bypass is shown in the following
illustration. This change-over occurs automatically in phase in less than one-quarter cycle of the input
waveform. The switching period is not long enough to cause interruptions to occur in most loads.
•
If the power flow is transferred to the bypass circuit due to an internal fault the UPS will continue to
supply power to the load through the bypass and indicate a system fault message (see "16.3 System
Fault Messages" on page 49).
•
If the power flow is transferred to the bypass circuit due to an overload condition (see "16.4 System
Warning Messages" on page 50), then the power flow will automatically transfer from the UPS's
bypass circuit back to the inverter circuit after removing the overload if set to do so (Under Setting >
Status Config & Ctl, set En AutoXfer to Enable).
MCCB
Input
Power
MOV Over-
current
Protection
FIGURE
NOTE: Bypass will be automatically disabled if the rated input and output voltages or frequencies are dif-
ferent.
12.2 On-Line (Run operation)
The following illustration shows circuit power flow when the UPS is operating normally in the Online Mode.
The UPS rectifier, including a boost chopper circuit, converts AC input power to DC power. The boost
chopper circuit maintains a constant voltage, with current limiting, for charging the batteries. The inverter
section generates a high quality sinusoidal output voltage. The unit's batteries are always maintained in a
constantly charged state when the UPS is in the run operation mode.
MCCB
Input
Power
MOV Over-
current
Protection
FIGURE
30
Bypass
Input
Fuse
Line Filter
Batteries
Negative Bus
12-1:
POWER FLOW IN BYPASS FOR ALL MODELS
Bypass
Input
Fuse
Rectifier/
Line Filter
Chopper
Batteries
Negative Bus
12-2:
POWER FLOW IN ONLINE MODE FOR ALL MODELS
T1000 Series UPS Installation and Operation Manual – 91074-002
*Static Switch
Output
Fuse
Rectifier/
Inverter
Chopper
+
* Switches are
–
solid state
devices.
*Static Switch
Transformer
Output
Fuse
Inverter
+
* Switches are
–
solid state
devices.
(Optional)
Auto-
Transformer
Output
Power
Power Flow
(Optional)
Auto-
Output
Power
Power Flow
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