Operation Modes; Ac Input Mode (Normal Operation); Circuit Bypass Mode - Toshiba UE3G2L036C61T Instruction Manual

Operating the UPS

Operation Modes

AC Input Mode (normal operation) The following illustration shows circuit power flow
when the UPS is operating normally in the ac input 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. It also
supplies a dc voltage of the proper level to the inverter section. The inverter section
generates a high quality sine wave output voltage. The unit's batteries are always
maintained in a constantly charged state when the UPS is in the normal operation mode.
MCCB
Input
Line Filter
power
Surge
absorber
Circuit-bypass Mode
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 less than 4 milliseconds in phase. 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 because of an overload and that overload condition ends within a
specified period of time then the power flow will be transferred back to the AC input
mode (normal operation) automatically. If the power flow is transferred to the
bypass circuit due to an external fault the UPS will shut down power through the
bypass to the load and indicate a system fault message. 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 system fault message DC-OC on page 43). If the power flow is
transferred to the bypass circuit due to an overload condition (see system warning
message OL: REDUCE LOAD on page 36 and AUTO RETRANSFER on page 40),
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 (see auto-
transfer setting on page 34).
MCCB
Input
power
Surge
absorber
TOSHIBA
Bypass
*Static
switch
Input
fuse
Rectifier/
Chopper
+
Batteries
_
Power Flow in AC input mode for all models
Bypass
*Static
Input
fuse
Rectifier/
Line Filter
Chopper
+
Batteries
_
Power Flow in bypass mode for all models
Output
fuse
Inverter
Line Filter
*Switches are
solid state
devices
switch
Output
fuse
Inverter
Line Filter
*Switches are
solid state
devices
25
Isolation
Transformer
Output
power
Power flow
Isolation
Transformer
Output
power
Power flow